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Highly efficient polymer supported monodisperse ruthenium-nickel nanocomposites for dehydrocoupling of dimethylamine borane
Journal of Colloid and Interface Science 526 (2018) 480–486
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Regular Article
Highly efficient polymer supported monodisperse ruthenium-nickel nanocomposites for dehydrocoupling of dimethylamine borane Betul Sen a, Esra Kuyuldar a, Buse Demirkan a, Tugba Onal Okyay a,b, Aysun Sß avk a, Fatih Sen a,⇑ a b
Sen Research Group, Biochemistry Department, Faculty of Arts and Science, Dumlupinar University, Evliya Celebi Campus, 43100 Kutahya, Turkey Department of Chemical Engineering, Faculty of Engineering, Usak University, Usak, Turkey
g r a p h i c a l a b s t r a c t The discovery of a superior dimethylamine borane dehydrogenation catalyst, more active than the many of the heterogeneous catalyst reported to date for the dehydrogenation of dimethylamine borane.
a r t i c l e
i n f o
Article history: Received 2 March 2018 Revised 10 May 2018 Accepted 10 May 2018
Keywords: Dehydrogeneration Dimethylamine-borane Metal-nanocatalyst Polymer supported
a b s t r a c t In the present study, highly effective and reusable monodisperse ruthenium–nickel (Ru-Ni) nanomaterials supported on poly(N-vinyl-2-pyrrolidone) (Ru-Ni@PVP) were synthesized (3.51 ± 0.38 nm) by a facile sodium-hydroxide-assisted reduction method; Ru and Ni reduction in PVP solution was accomplished. The prepared nanocomposites were characterized by TEM, HRTEM, XRD, and XPS and performed as a catalyst for dehydrocoupling of dimethylamine-borane (DMAB). It was found that Ru-Ni nanomaterials are one of the most active catalysts at low concentrations and temperature for dehydrocoupling of DMAB. This catalyst with its turnover frequency of 458.57 h 1 exhibits one of the best results among all the catalysts prepared in the literature for dehydrocoupling of DMAB. Significantly low Ea value (36.52 ± 3 kJ mol 1) was also found for dehydrocoupling of DMAB. Ó 2018 Elsevier Inc. All rights reserved.
1. Introduction Hydrogen is an eco-friendly and clean energy carrier to generate electricity and there are many hydrogen sources. For example, NaBH4 (SBH) as a hydrogen source is considered as one of the best ⇑ Corresponding author. E-mail address: [email protected] (F. Sen). https://doi.org/10.1016/j.jcis.2018.05.021 0021-9797/Ó 2018 Elsevier Inc. All rights reserved.
energy carriers as it includes high hydrogen content (10.8%), and is also available, very stable, easy to handle and inflammable. In addition, ammonia borane compounds and derivatives (ABs) are also suggested as another group of good hydrogen energy sources because of their high hydrogen content (19.6%), great stability and solubility in aqueous solutions at low temperatures [1,2]. To generate hydrogen at room temperature with the help of ABs, it can be possible by using a simple method if there is an efficient
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catalyst. Therefore, various catalysts are being used in order to obtain hydrogen with the help of dehydrocoupling of the ABs [3–20]. Lately, dimethylamine-borane (DMAB), which is a derivative of ABs, has paid much attention since DMAB carries many benefits; it has no toxicity, great stability in air and aqueous solutions, and it is also eco-friendly and shows a crystalline structure at room temperature, In addition to this, as the reaction products of DMAB are relatively simple to deal with compared to other products of different ABs (Scheme 1), DMAB has been revealed as a model compound. Moreover, numerous catalysts have been synthesized such as Rh, Ru and Ir complexes, trans-Ru(H)2 (PMe3)(PNPH) and Ru(H) (PMe3)(PNP), [Rh(1,5-cod)(m-Cl)]2, colloidal Rh/[Oct4N]Cl, Rh/ Al2O3 and RhCl3, [Cp2Ti], [RuH2 (ɳ2-H2)2 (PCy3)2] and [RuH2 (ɳ2: ɳ2-H2B-N (Me2)2 (PCy3)2], Rh, Ru, Re complexes, clusters and nanoparticles for the dehydrocoupling of DMAB [21–37]. Generally, nanoparticles and nanocomposites have been used for a variety of applications [38–52] but there are only a few papers that examine the dehydrocoupling of dimethylamine borane with the help of polymer-supported bimetallic alloy nanocomposites [53–56]. For this purpose, in this paper, the preparation and characterization of a novel monodisperse polymer supported metalnanocatalyst (Ru–Ni@PVP), was synthesized and performed for dehydrocoupling of dimethylamine borane. To produce these novel nanocatalysts, both metals (Ru and Ni) were co-reduced by a facile sodium- hydroxide-assisted reduction method, which enables stable and smaller nanoparticle dispersion with the help of OH ligands. To characterize the prepared nanocatalysts, TEM, HRTEM, EELS XRD, and XPS were utilized. Here, it is worth noting that the prepared nanomaterials including noble metals (in our case Ru) can be expensive, but their outstanding performances make them special materials especially for practical dihydrogen generation systems utilizing dimethylamine borane as a hydrogen storage material and eliminate high catalyst charge concerns.
2 Me2NHBH3
Catalyst
(Me2N.BH2)2
+ 2H2
Scheme 1. The catalytic dehydrocoupling reaction of dimethylamine-borane.
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2. Experimental methods 2.1. Production of Ru–Ni@PVP nanomaterials Since the materials containing OH ligands are much more favorable for the formation of small NPs on the supports than those without OH ligands, a facile sodium- hydroxide-assisted reduction method was performed to prepare Ru-Ni@PVP nanomaterials. Firstly, the optimization experiments related to the ratios of Ru/Ni and the PVP/metal were performed and optimum ratio of Ru/Ni and the PVP/metal were found to be 1:1 and 5:1, respectively as shown in Figs. S1 and S2. By using these ratios, typically to prepare Ru-Ni@PVP nanomaterials, 2.5 mmoles of PVP, 0.25 mmoles of RuCl3 and 0.25 mmoles of Ni were mixed with each other. The resultant aqueous suspension was further homogenized under sonication for 30 min. Then, 12 mg of NaBH4 dissolved in 1.0 mL of 3.0 M NaOH solution was added to the above-obtained solution with vigorous shaking, resulting in the generation of the catalyst as a brownish black final color. The stability and the homogeneity of the catalysts look like very good. The reaction was performed in an inert atmosphere. After characterization of prepared nanomaterials, specific analytical measurements, catalytic activity, stability, productivity and reusability performances of Ru-Ni@PVP nanomaterials were investigated for dehydrocoupling of dimethylamine borane as shown in Scheme 2. (see the Supporting Information for detailed information). 3. Results and discussion 3.1. Analytical results for Ru-Ni@PVP nanomaterials Preliminary characterizations of monodisperse Ru-Ni@PVP nanomaterials were performed by TEM, HRTEM, XRD, and XPS. Production of Ru-Ni nanomaterials was accomplished employing a facile sodium- hydroxide-assisted reduction method in the presence of poly(N-vinyl-2-pyrrolidone). In this method, the coreduction of Ru and Ni was performed with the help of ultrasonic tip sonicator. Here, PVP was used as both stabilizing and reducing agents. The final mixture was brownish black, which indicates the reduction of 2+ and 3+ oxidation state of the metals to zero
Scheme 2. The general reaction set-up of the dehydrocoupling reaction of DMAB ((CH3)2 NHBH3) by using nanocatalysts.
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Fig. 1. (a) Transmission electron microscopy, high-resolution transmission electron microscopy, and size distribution (b) EELS mapping (c) EELS line profile of monodisperse Ru–Ni@PVP.
oxidation state and alloy nanoparticles were formed. As indicated Fig. 1, TEM results reveal the microstructural features, composition, and morphology of Ru-Ni@PVP nanomaterials. The mean size measured in this investigation was found to be around 3.51 ± 0.38 nm. HRTEM investigation result was also demonstrated in Fig. 1a and it can be seen from here that the nanoparticles were mostly spherical. No agglomeration was noticed in the TEM and HR-TEM analyses. Furthermore, HR-TEM results depicted the lattice fringes of 0.21 nm and this finding is the exact same value for the nominal Ru (1 0 1) spacing of 0.21 nm [57]. As shown in Fig. 1b and c, EELS mapping and line profile indicate the confirmation of the existence of both Ru and Ni at the same time in the prepared catalyst which indicates the formation of Ru-Ni alloy. The morphology and size of monodisperse Ru-Ni@PVP nanoparticles were investigated with x-ray diffraction technique. As a control experiment, XRD of PVP, Ru@PVP, and Ni@PVP was given in order to confirm the existence of Ru–Ni@PVP nanoparticles. As shown in Fig. 2, the mixture of Ru (1 0 1) and Ni (1 1 1) crystal
Fig. 2. XRD of PVP, Ru@PVP, Ni@PVP, and Ru–Ni@PVP nanoparticles.
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Fig. 3. (a) 2D and (b) 3D view of Ru 3p and (c) 2D and (d) 3D view of Ni 2p XPS spectra of Ru–Ni@PVP NPs.
plane in the prepared catalyst was easily observed at 44.2° which confirms the alloy formation of Ru-Ni@PVP nanocomposites [58]. The XPS technique was used to analyze the electronic structure and surface oxidation of the novel Ru-Ni@PVP nanocatalyst. The XPS spectra of the Ru 3p and Ni 2p regions of the nanocatalyst were given in Fig. 3. For the Ru 3p, two peaks can be recognized at 463.1 eV and 483.2 eV, which stand for the metallic state of Ru and some of the +3 oxidation state of Ru respectively. In addition, two other peaks identify Ni 2p spectra (2p1/2, 2p3/2) can be seen at 855.3 eV and 873.3 eV, respectively, which are directly related to Ni (0) and Ni (II), as illustrated in the Fig. 3c and d. This higher oxidation state of the Ru and Ni in the prepared catalyst is most probably due to the unreduced species and/or some of the oxidized species of Ru and Ni [59].
3.2. The dehydrocoupling of DMAB with the help of Ru–Ni@PVP nanomaterials In the present study, the stability and efficiency of monodisperse Ru–Ni@PVP nanoparticles were demonstrated for catalytic dehydrogenation of DMAB. As shown in Fig. 4a, various concentrations of monodisperse Ru–Ni@PVP nanoparticles against time were shown for dehydrogenation of DMAB at room temperature. A sudden hydrogen evolution starts linearly with no induction period and continues till the completion of catalytic dehydrogenation of DMAB. The conversion of (CH3)2NHBH3 to [(CH3)2NBH2]2 was demonstrated by NMR spectra (d = 12.7 ppm to d = 5 ppm, respectively) showing the complete dehydrogenation of DMAB as shown in Fig. S3 (in the production of 1.0 equivalent of H2) even at room temperature. Besides, the results of catalytic dehydrogena-
Fig. 4. (a) Plot of nH2/nDMAB vs time for dehydrocoupling of DMAB in the presence of Ru-Ni/PVP NPs with various concentrations of the catalyst at 25 ± 0.1 °C. (b) % conversion graph at different times for monodisperse Ru-Ni/PVP NPs (7.5% mol) catalyzed dehydrocoupling of DMAB in THF at various temperatures.
tion of DMAB with the help of monodisperse Ru–Ni@PVP nanoparticles were shown in the Fig. 4b in various temperatures such as 20, 25, 30 and 35 °C. The rate constants of hydrogen production at these four different temperatures were calculated using this figure during dehydrogenation of DMAB. With the help of Arrhenius and Eyring graph as shown in Fig. 5a and b, the Ea value (36.52 ± 3 kJ mol 1), the activation enthalpy (DH# = 34.02 ± 2 kJmol 1) and activation entropy (DS# = 84.47 Jmol 1K 1) were calculated. High negative values of activation entropy and small activation
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Fig. 5. (a) Arrhenius and (b) Eyring plot of monodisperse Ru-Ni/PVP NPs.
Table 1 Different catalysts, their turnover frequencies and conversion values for DMAB dehydrogenation.
*
Entry
(Pre) Catalysts
Conv. (%)
TOF
Solvent
Temperature (oC)
Ref
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
RuNi@PVP Cp2 Ti Trans RuMe2 (PMe)₄ [Cr (CO)₅ (thf)] [Rh (1,5-cod) m-Cl]2 [Rh Cl (PHCy2)3] [Rh (1,5-cod)2] Otf [Ir(1,5-cod) m-Cl]2 [Ru H (PMe3) (NC2H4PPr2)2] Pd/C Ir Cl3 Rh Cl3 Trans PdCl2 (P(o-tolyl)3)2 Rh Cl (PPh3)3 (Idipp) Cu Cl Pt(0)/TPA@AC [Rh (1,5-cod) (dmpe)] PF₆ [Cp *Rh (m-Cl) Cl]2 [Cr (CO)₅ (ɳ1-BH3NMe3)] PdCo @PVP PdNi@PEDOT Pd@GO H Rh (CO) (PPh3)3 Ni (skeletal) Pt(0)/BA Pt NPs@CBH Rh (0)/[Noct₄] Cl RuNiPt@GO Pt(0)/TBA RuCo@f -MWCNT [(C₅H3-1,3 (SiMe3)2)2 Ti]2 Pt@PANI-rGO PdNi@GO Pt(0)/AA
100 100 100 97 100 100 95 95 100 95 25 90 20 100 100 100 95 100 97 100 100 100 5 100 100 100 90 100 100 100 100 100 100 100
458.57 12.3 12.4 13.4 12.5 2.6 12.0 0.7 1.5 2.8 0.3 7.9 0.2 4.3 0.3 34.14 1.7 0.9 19.9 330 451.28 38.02 0.1 3.2 24.88 70.28 8.2 727 31.24 775.28 420.0 42.94 271.90 15.0
THF toluene THF THF THF hexane THF THF THF THF THF THF THF THF NI* THF THF THF benzene THF THF THF THF Bis(2-methoxyethyl) ether THF THF THF THF THF THF THF THF THF THF
25 20 25 65 25 70 25 25 25 25 25 25 25 25
This study 26 22 44 22 33 22 22 15 22 22 22 22 22 42 30 22 21 44 43 45 46 22 54 50 47 22 49 50 55 52 36 56 34
25 25 25 25 25 25 25 25 60 25 25 25 25 25 25 25 25 25 25
No information.
enthalpy values refer to an associate mechanism in the catalytic dehydrocoupling of DMAB. Briefly, it is important to say that H2 gas (1 mol of H2 per 1 mol of DMAB) was released completely within a very short time when Ru–Ni@PVP nanoparticles were used. The TOF number was found to be 458.57 h 1 at 25 ± 0.1 °C. As shown in Table 1, the monodisperse Ru–Ni@PVP nanoparticles became one of the best catalytic activity (TOF value = 458.57 h 1) for dehydrocoupling of DMAB compared to others in the literature. In addition, some comparative studies were carried out; the catalytic performances of Ru@PVP
and Ni@PVP nanoparticles, physically mixed Ru@PVP–Ni@PVP nanomaterials, and Ru–Ni@PVP alloy nanomaterials were examined, and the alloy characteristic structure of Ru-Ni@PVP nanoparticles was proved. For this purpose, in these investigations, the turnover frequencies (TOFs) for Ni@PVP nanoparticles, Ru@PVP nanoparticles, physically mixed Ru@PVP–Ni@PVP nanoparticles and newly synthesized Ru-Ni@PVP bimetallic nanoparticles were calculated. The higher TOF value of the Ru-Ni@PVP nanoparticles compared to the other prepared ones indicates the alloy character of prepared nanocomposites. Besides, as control experiments
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shown in Fig. S4, the precursor materials of Ru and Ni were performed for dehydrocoupling of DMAB but it wasn’t observed the complete conversion of DMAB with the help of those materials. In conclusion, monodisperse Ru–Ni@PVP nanoparticles are very promising, isolable and reusable nanocatalysts for dehydrocoupling of DMAB. In the prepared catalyst, as PVP generated enough stability and possible synergistic and cooperative relationship between Ru and Ni, our system supplied outstanding catalytic performance towards the dehydrocoupling of DMAB. Additionally, the reusability performance of PVP-stabilized Ru-Ni nanoparticles for the hydrogenation reaction of DMAB was investigated and the results were given in Fig. S5; the nanoparticles maintain their initial performance until the 4th experiment without any significant reduction. 78% of the initial performance of the monodisperse Ru-Ni@PVP was observed for dehydrocoupling of DMAB. This decrease can be explained by the increase in the amount of product, the reduction of the surface area of the nanoparticles, which reduces the availability of catalytically active sites and the accumulation of nanoclusters (Fig. S5). By the way, even after the 4th cycle, the catalyst maintained its own content without any leaching. 4. Conclusions In summary, PVP-stabilized ruthenium-nickel nanomaterials were synthesized and their analytical investigations and usage for catalytic dehydrogenation of DMAB were performed in this study. The most important points from the study were given below: Since the materials containing OH ligands are much more favorable for the formation of small NPs on the supports than those without OH ligands, a facile sodium- hydroxideassisted reduction method was performed to prepare Ru-Ni@PVP nanomaterials. In this method, ruthenium and nickel salts were co-reduced in the presence of PVP. Ultrasonication was utilized to augment the dispersion. The results indicated that the method is very efficient to get monodisperse Ru– Ni nanoparticles on PVP without any agglomeration problem. The prepared nanocomposites were characterized by TEM, HRTEM, XRD, and XPS and performed as a catalyst for dehydrocoupling of dimethylamine-borane (DMAB). The results indicate the alloy formation of Ru and Ni in the presence of PVP in the prepared catalyst. Ru–Ni@PVP nanoparticles showed the outstanding catalytic performance for dehydrocoupling of DMAB. The one of the best catalytic efficiency was obtained as shown in Table 1. Ea value (36.52 ± 3 kJmol 1), the activation enthalpy (DH# = 34. 02 ± 2 kJmol 1) and activation entropy (DS# = 84.47 Jmol 1K 1) were calculated by using Arrhenius and Eyring plots. High negative values of activation entropy and small activation enthalpy values refer to an associate mechanism in the catalytic dehydrocoupling of DMAB. 78% of the initial performance of the monodisperse Ru-Ni@PVP was observed for dehydrocoupling of DMAB even after the 4th cycle. In near future, monodisperse Ru–Ni@PVP nanoparticles have promising and great potential to generate hydrogen gas in fuel cells via catalytic dehydrocoupling of DMAB.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.jcis.2018.05.021.
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References [1] D.A.J. Rand, R.M. Dell, The hydrogen economy: a threat or an opportunity for lead-acid batteries?, J Power Sources 144 (2005) 568–578. [2] Q. Zhang, G.M. Smith, Y. Wu, Catalytic hydrolysis of sodium borohydride in an integrated reactor for hydrogen generation, Int. J. Hydrogen Energy 32 (2007) 4731–4735. [3] Basic Research Needs For the Hydrogen Economy, Report of the basic energy sciences workshop on Hydrogen production, storage and use, May 13–15, Office of Science, U.S. Department of Energy, 2003. www.sc.doe.gov/bes/ hydrogen.pdf. [4] J. Lee, K.Y. Kong, C.R. Jung, E. Cho, S.P. Yoon, J. Han, T.G. Lee, S.W. Nam, A structured Co-B catalyst for hydrogen extraction from NaBH4 solution, Catal. Today 120 (2007) 305–310. [5] S.C. Amendola, J.M. Janjua, N.C. Spencer, M.T. Kelly, P.J. Petillo, S.L. SharpGoldman, M. Binder, A safe, portable, hydrogen gas generator using aqueous borohydride solution and Ru catalyst, Int. J. Hydrogen Energy 25 (2000) 969– 975. [6] F.H. Stephens, V. Pons, R.T. Baker, Ammonia-borane: the hydrogen source par excellence, Dalton Trans. 25 (2007) 2613–2626. [7] N. Mohajeri, A. T-Raissi, O. Adebiyi, Hydrolytic cleavage of the ammoniaborane complex for hydrogen production, J. Power Sources 167 (2007) 482– 485. [8] P.V. Ramachandran, P.D. Gagare, Preparation of ammonia borane in high yield and purity, methanolysis, and regeneration, Inorg. Chem. 46 (2007) 7810– 7817. [9] Q. Xu, M. Chandra, Catalytic activities of non-noble metals for hydrogen generation from aqueous ammonia–borane at room temperature, J. Power Sources 163 (2006) 364–370. [10] Q. Xu, M. Chandra, A portable hydrogen generation system, catalytic hydrolysis of ammonia–borane, J. Alloys Compd. 446–447 (2007) 729–732. [11] T. Umegaki, J.M. Yan, X.B. Zhang, H. Shioyama, N. Kuriyama, Q. Xu, Preparation and catalysis of poly(N-vinyl-2-pyrrolidone) (PVP) stabilized nickel catalyst for hydrolytic dehydrogenation of ammonia borane, Int. J. Hydrogen Energy 34 (2009) 3816–3822. [12] T. Umegaki, J.M. Yan, X.B. Zhang, H. Shioyama, N. Kuriyama, Q. Xu, Hollow NieSiO2 nanosphere-catalyzed hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage, J. Power Sources 191 (2009) 209– 216. [13] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Iron-nanoparticle-catalyzed hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage, Angew. Chem. Int. Ed. 47 (2008) 2287–2289. [14] R. Fernandes, N. Patel, A. Miotello, Hydrogen generation by hydrolysis of the alkaline NaBH4 solution with Cr-promoted Co–B amorphous catalyst, Appl. Catal. B 92 (2009) 68–74. [15] A. Friederich, M. Drees, S. Schneider, Ruthenium-catalyzed dimethylamineborane dehydrogenation, stepwise metal-centered dehydrocyclization, Chem. Eur. J. 15 (2009) 10339–10342. [16] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Room temperature hydrolytic dehydrogenation of ammonia borane catalyzed by Co nanoparticles, J. Power Sources 195 (2010) 1091–1094. [17] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Synthesis of longtime water/ air-stable Ni nanoparticles and their high catalytic activity for hydrolysis of ammonia borane for hydrogen generation, Inorg. Chem. 48 (2009) 7389– 7393. [18] D.G. Tong, X.L. Zeng, W. Chu, D. Wang, P. Wu, Magnetically recyclable hollow Co–B nanospindles as catalysts for hydrogen generation from ammonia borane, J. Mater. Sci. 45 (2010) 2862–2867. [19] N. Patel, R. Fernandes, G. Guella, A. Miotello, Nanoparticle-assembled Co-B thin film for the hydrolysis of ammonia borane: a highly active catalyst for hydrogen production, Appl. Catal. B 95 (2010) 137–143. [20] Y. Yamada, K. Yano, Q. Xu, S. Fukuzumi, Cu/Co3O4 nanoparticles as catalysts for hydrogen evolution from ammonia borane by hydrolysis, J. Phys. Chem. C 114 (2010) 16456–16462. [21] C.A. Jaska, K. Temple, A.J. Lough, I. Manners, Transition metal-catalyzed formation of boron nitrogen bonds: catalytic dehydrocoupling of amineborane adducts to form amino boranes and borazines, J. Am. Chem. Soc. 125 (2003) 9424–9434. [22] C.A. Jaska, I. Manners, Heterogeneous or homogeneous catalysis? mechanistic studies of the rhodium-catalyzed dehydrocoupling of amine-borane and phosphine-borane adducts, J. Am. Chem. Soc. 126 (2004) 9776–9785. [23] Y. Chen, J.L. Fulton, J.C. Linehan, T. Autrey, In situ spectroscopic studies of the rhodıum catalyzed production of hydrogen from dimethylamıne borane homogeneous or heterogeneous catalysis, Prepr. Pap. Am. Chem. Soc. Div. Fuel Chem. 49 (2004) 972–973. [24] Y. Chen, J.L. Fulton, J.C. Linehan, T. Autrey, In Situ XAFS and NMR Study of Rhodium-Catalyzed dehydrogenation of dimethylamine borane, J. Am. Chem. Soc. 127 (2005) 3254–3255. [25] T.J. Clark, C.A. Russell, I. Manners, Homogeneous, Titanocene-catalyzed dehydrocoupling of amine borane adducts, J. Am. Chem. Soc. 128 (2006) 9582–9583. [26] M.E. Sloan, A. Staubitz, T.J. Clark, C.A. Russell, G.C. Lloyd-Jones, I. Manners, Homogeneous catalytic dehydrocoupling/dehydrogenation of amine borane adducts by the early transition metal, group 4 metallocene complexes, J. Am. Chem. Soc. 132 (2010) 3831–3841.
486
B. Sen et al. / Journal of Colloid and Interface Science 526 (2018) 480–486
[27] G. Alcaraz, L. Vendier, E. Clot, S. Sabo-Etienne, Ruthenium Bis(r-B-H) aminoborane complexes from dehydrogenation of amine–boranes, Trapping of H2B-NH2, Angew. Chem. Int. Ed. 49 (2010) 918–920. [28] Y. Yildiz, E. Erken, H. Pamuk, F. Sen, Monodisperse Pt nanoparticles assembled on reduced graphene oxide: highly efficient and reusable catalyst for methanol oxidation and dehydrocoupling of dimethylamine-borane (DMAB), J. Nanosci. Nanotechnol. 16 (2016) 5951–5958. [29] B. Çelik, G. Basßkaya, Ö. Karatepe, E. Erken, F. Sßen, Monodisperse Pt(0)/DPA@GO nanoparticles as highly active catalysts for alcohol oxidation and dehydrogenation of DMAB, Int. J. Hydrogen Energy 41 (2016) 5661–5669. [30] B. Çelik, E. Erken, S. Erisß, Y. Yıldız, B. S ß ahin, H. Pamuk, F. Sen, Highly monodisperse Pt(0)@AC NPs as highly efficient and reusable catalysts: the effect of the surfactant on their catalytic activities in room temperature dehydrocoupling of DMAB, Catal. Sci. Tech. 6 (2016) 1685–1692. [31] Y. Jiang, H. Berke, Dehydrocoupling of dimethylamine-borane catalyzed by rhenium complexes and its application in olefin transfer-hydrogenations, Chem. Commun. 34 (2007) 3571–3573. [32] J.L. Fulton, J.C. Linehan, T. Autrey, M. Balasubramanian, Y. Chen, N.K. Szymczak, When is a nanoparticle a cluster? an operando EXAFS study of amine borane dehydrocoupling by Rh4-6 Clusters, J. Am. Chem. Soc. 129 (2007) 11936– 11949. [33] M.E. Sloan, T.J. Clark, I. Manners, Homogeneous catalytic dehydrogenation/ dehydrocoupling of amine-borane adducts by the Rh(I) Wilkinson’s complex analog RhCl(PHCy2)3 (Cy = cyclohexyl), Inorg. Chem. 48 (2009) 2429–2435. [34] F. Sen, Y. Karatasß, M. Gülcan, M. Zahmakıran, Amylamine stabilized platinum (0) nanoparticles: active and reusable nanocatalyst in the room temperature dehydrogenation of dimethylamine-borane, RSC Adv. 4 (4) (2014) 1526–1531. [35] M. Munoz-Olasagasti, A. Telleria, J. Perez-Miqueo, M.A. Garralda, Z.A. Freixa, A readily accessible ruthenium catalyst for the solvolytic dehydrogenation of amine-borane adducts, Dalton Trans. 43 (2014) 11404–11409. [36] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Polymer-Graphene hybrid decorated Pt nanoparticles as highly efficient and reusable catalyst for the dehydrogenation of dimethylamine-borane at room temperature, Int. J. Hydrogen Energy 42 (36) (2017) 23284–23291. [37] Z.S. Yang, J.J. Wu, Pd/Co bimetallic nanoparticles: coelectrodeposition under the protection of PVP and enhanced electrocatalytic activity for ethanol electrooxidation, Fuel Cells 12 (2012) 420. [38] R. Wang, S. Liao, S. Ji, High-performance Pd-based catalysts for oxidation of formic acid, J. Power Sources 180 (2008) 205. [39] C. Jung, C.M. Sanchez-Sanchez, C.L. Lin, J. Rodriguez-Lopez, A.J. Bard, The electrocatalytic activity of Pd_Co bimetallic mixtures for formic acid oxidation studied by scanning electrochemical microscopy, Anal. Chem. 81 (2009) 7003. [40] M. Yin, Q. Li, J.O. Jensen, Y. Huang, L.N. Cleemann, N.J. Bjerrum, W. Xing, Tungsten carbide promoted Pd and Pd-Co electrocatalysts for formic acid electrooxidation, J. Power Sources 219 (2012) 106. [41] X. Wang, Y. Xia, The electrocatalytic performance of PdCo-C catalyst for formic acid oxidation, Electrochem. Commun. 10 (2008) 1644. [42] R.J. Keaton, J.M. Blacquiere, R.T. Baker, Base metal catalyzed dehydrogenation of ammonia borane for chemical hydrogen storage, J. Am. Chem. Soc. 129 (7) (2007) 1844–1845. [43] B. Celik, Y. Yildiz, H. Sert, E. Erken, Y. Koskun, F. Sen, Monodispersed palladium-cobalt alloy nanoparticles assembled on poly(N-vinylpyrrolidone) (PVP) as a highly effective catalyst for dimethylamine borane (DMAB) dehydrocoupling, RSC Adv. 6 (2016) 24097–24102.
[44] Y. Kawano, M. Uruichi, M. Shiomi, S. Taki, T. Kawaguchi, T. Kakizawa, H. Ogino, Dehydrocoupling reactions of borane secondary and primary amine adducts catalyzed by group-6 carbonyl complexes: formation of aminoboranes and borazines, J. Am. Chem. Soc. 131 (2009) 14946. [45] B. Sen, S. Kuzu, E. Demir, E. Yildirir, F. Sen, Highly efficient catalytic dehydrogenation of dimethyl ammonia borane via monodisperse palladiumnickel alloy nanoparticles assembled on PEDOT, Int. J. Hydrogen Energy 42 (36) (2017) 23307–23314. [46] B. Sen, A. Aygün, T. Onal Okyay, A. Savk, R. Kartop, F. Sen, Monodisperse palladium nanoparticles assembled on graphene oxide with the high catalytic activity and reusability in the dehydrogenation of dimethylamine-borane, Int. J. Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.03.175. [47] B. Sen, A. Savk, F. Sen, Highly efficient monodisperse nanoparticles confined in the carbon black hybrid material for hydrogen liberation, J. Colloid Interf. Sci. 520 (2018) 112–118. [48] X. Yang, F. Cheng, J. Liang, Z. Tao, J. Chen, PtxNi1 x nanoparticles as catalysts for hydrogen generation from hydrolysis of ammonia borane, Int. J. Hydrogen Energy 34 (2009) 8785–8791. [49] B. Sen, S. Kuzu, E. Demir, T. Onal Okyay, F. Sen, Hydrogen liberation from the dehydrocoupling of dimethylamine-borane at room temperature by using novel and highly monodispersed RuPtNi nanocatalysts decorated with graphene oxide, Int. J. Hydrogen Energy 42 (36) (2017) 23299–23306. [50] E. Erken, H. Pamuk, O. Karatepe, G. Baskaya, H. Sert, O.M. Kalfa, F. Sen, New Pt (0) nanoparticles as highly active and reusable catalysts in the C1–C3 alcohol oxidation and the room temperature dehydrocoupling of DimethylamineBorane (DMAB), J. Cluster Sci. 27 (9) (2016) 23. [51] B. Celik, S. Kuzu, E. Erken, H. Sert, Y. Koskun, F. Sen, Nearly monodisperse carbon nanotube furnished nanocatalysts as highly efficient and reusable catalyst for dehydrocoupling of DMAB and C1 to C3 alcohol oxidation, Int. J. Hydrogen Energy 41 (2016) 3093–3101. [52] D. Pun, E. Lobkovsky, P.J. Chirik, Amine-borane dehydrogenation promoted by isolable zirconium sandwich, titanium sandwich, and N2 complexes, Chem. Commun. 44 (2007) 3297. [53] R.J. Keaton, J.M. Blacquiere, R.T. Baker, Base metal catalyzed dehydrogenation of ammonia borane for chemical hydrogen storage, J. Am. Chem. Soc. 129 (2007) 11936. [54] A.P.M. Robertson, R. Suter, L. Chabanne, G.R. Whittel, I. Manners, Heterogeneous dehydrocoupling of amine-borane adducts by skeletal nickel catalysts, Inorg. Chem. 50 (2011) 12680. [55] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Highly monodisperse RuCo nanoparticles decorated on functionalized multiwalled carbon nanotube with the highest observed catalytic activity in the dehydrogenation of dimethylamine borane, Int. J. Hydrogen Energy 42 (36) (2017) 23292–23298. [56] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Monodisperse palladium-nickel alloy nanoparticles assembled on graphene oxide with the high catalytic activity and reusability in the dehydrogenation of dimethylamine-borane, Int. J. Hydrogen Energy 42 (36) (2017) 23276–23283. [57] D.B. Williams, C.B. Carter, Transmission Electron Microscopy A Textbook for Materials Science, first ed., Springer, 1996. [58] H.P. Klug, L.E. Alexander, X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials, second ed., Wiley, 1974. [59] P. Van der Heide, -ray Diffraction Procedures for Polycrystalline and Amorphous Materials, first ed., John Wiley & Sons, Inc., 2012.
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Regular Article
Highly efficient polymer supported monodisperse ruthenium-nickel nanocomposites for dehydrocoupling of dimethylamine borane Betul Sen a, Esra Kuyuldar a, Buse Demirkan a, Tugba Onal Okyay a,b, Aysun Sß avk a, Fatih Sen a,⇑ a b
Sen Research Group, Biochemistry Department, Faculty of Arts and Science, Dumlupinar University, Evliya Celebi Campus, 43100 Kutahya, Turkey Department of Chemical Engineering, Faculty of Engineering, Usak University, Usak, Turkey
g r a p h i c a l a b s t r a c t The discovery of a superior dimethylamine borane dehydrogenation catalyst, more active than the many of the heterogeneous catalyst reported to date for the dehydrogenation of dimethylamine borane.
a r t i c l e
i n f o
Article history: Received 2 March 2018 Revised 10 May 2018 Accepted 10 May 2018
Keywords: Dehydrogeneration Dimethylamine-borane Metal-nanocatalyst Polymer supported
a b s t r a c t In the present study, highly effective and reusable monodisperse ruthenium–nickel (Ru-Ni) nanomaterials supported on poly(N-vinyl-2-pyrrolidone) (Ru-Ni@PVP) were synthesized (3.51 ± 0.38 nm) by a facile sodium-hydroxide-assisted reduction method; Ru and Ni reduction in PVP solution was accomplished. The prepared nanocomposites were characterized by TEM, HRTEM, XRD, and XPS and performed as a catalyst for dehydrocoupling of dimethylamine-borane (DMAB). It was found that Ru-Ni nanomaterials are one of the most active catalysts at low concentrations and temperature for dehydrocoupling of DMAB. This catalyst with its turnover frequency of 458.57 h 1 exhibits one of the best results among all the catalysts prepared in the literature for dehydrocoupling of DMAB. Significantly low Ea value (36.52 ± 3 kJ mol 1) was also found for dehydrocoupling of DMAB. Ó 2018 Elsevier Inc. All rights reserved.
1. Introduction Hydrogen is an eco-friendly and clean energy carrier to generate electricity and there are many hydrogen sources. For example, NaBH4 (SBH) as a hydrogen source is considered as one of the best ⇑ Corresponding author. E-mail address: [email protected] (F. Sen). https://doi.org/10.1016/j.jcis.2018.05.021 0021-9797/Ó 2018 Elsevier Inc. All rights reserved.
energy carriers as it includes high hydrogen content (10.8%), and is also available, very stable, easy to handle and inflammable. In addition, ammonia borane compounds and derivatives (ABs) are also suggested as another group of good hydrogen energy sources because of their high hydrogen content (19.6%), great stability and solubility in aqueous solutions at low temperatures [1,2]. To generate hydrogen at room temperature with the help of ABs, it can be possible by using a simple method if there is an efficient
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catalyst. Therefore, various catalysts are being used in order to obtain hydrogen with the help of dehydrocoupling of the ABs [3–20]. Lately, dimethylamine-borane (DMAB), which is a derivative of ABs, has paid much attention since DMAB carries many benefits; it has no toxicity, great stability in air and aqueous solutions, and it is also eco-friendly and shows a crystalline structure at room temperature, In addition to this, as the reaction products of DMAB are relatively simple to deal with compared to other products of different ABs (Scheme 1), DMAB has been revealed as a model compound. Moreover, numerous catalysts have been synthesized such as Rh, Ru and Ir complexes, trans-Ru(H)2 (PMe3)(PNPH) and Ru(H) (PMe3)(PNP), [Rh(1,5-cod)(m-Cl)]2, colloidal Rh/[Oct4N]Cl, Rh/ Al2O3 and RhCl3, [Cp2Ti], [RuH2 (ɳ2-H2)2 (PCy3)2] and [RuH2 (ɳ2: ɳ2-H2B-N (Me2)2 (PCy3)2], Rh, Ru, Re complexes, clusters and nanoparticles for the dehydrocoupling of DMAB [21–37]. Generally, nanoparticles and nanocomposites have been used for a variety of applications [38–52] but there are only a few papers that examine the dehydrocoupling of dimethylamine borane with the help of polymer-supported bimetallic alloy nanocomposites [53–56]. For this purpose, in this paper, the preparation and characterization of a novel monodisperse polymer supported metalnanocatalyst (Ru–Ni@PVP), was synthesized and performed for dehydrocoupling of dimethylamine borane. To produce these novel nanocatalysts, both metals (Ru and Ni) were co-reduced by a facile sodium- hydroxide-assisted reduction method, which enables stable and smaller nanoparticle dispersion with the help of OH ligands. To characterize the prepared nanocatalysts, TEM, HRTEM, EELS XRD, and XPS were utilized. Here, it is worth noting that the prepared nanomaterials including noble metals (in our case Ru) can be expensive, but their outstanding performances make them special materials especially for practical dihydrogen generation systems utilizing dimethylamine borane as a hydrogen storage material and eliminate high catalyst charge concerns.
2 Me2NHBH3
Catalyst
(Me2N.BH2)2
+ 2H2
Scheme 1. The catalytic dehydrocoupling reaction of dimethylamine-borane.
481
2. Experimental methods 2.1. Production of Ru–Ni@PVP nanomaterials Since the materials containing OH ligands are much more favorable for the formation of small NPs on the supports than those without OH ligands, a facile sodium- hydroxide-assisted reduction method was performed to prepare Ru-Ni@PVP nanomaterials. Firstly, the optimization experiments related to the ratios of Ru/Ni and the PVP/metal were performed and optimum ratio of Ru/Ni and the PVP/metal were found to be 1:1 and 5:1, respectively as shown in Figs. S1 and S2. By using these ratios, typically to prepare Ru-Ni@PVP nanomaterials, 2.5 mmoles of PVP, 0.25 mmoles of RuCl3 and 0.25 mmoles of Ni were mixed with each other. The resultant aqueous suspension was further homogenized under sonication for 30 min. Then, 12 mg of NaBH4 dissolved in 1.0 mL of 3.0 M NaOH solution was added to the above-obtained solution with vigorous shaking, resulting in the generation of the catalyst as a brownish black final color. The stability and the homogeneity of the catalysts look like very good. The reaction was performed in an inert atmosphere. After characterization of prepared nanomaterials, specific analytical measurements, catalytic activity, stability, productivity and reusability performances of Ru-Ni@PVP nanomaterials were investigated for dehydrocoupling of dimethylamine borane as shown in Scheme 2. (see the Supporting Information for detailed information). 3. Results and discussion 3.1. Analytical results for Ru-Ni@PVP nanomaterials Preliminary characterizations of monodisperse Ru-Ni@PVP nanomaterials were performed by TEM, HRTEM, XRD, and XPS. Production of Ru-Ni nanomaterials was accomplished employing a facile sodium- hydroxide-assisted reduction method in the presence of poly(N-vinyl-2-pyrrolidone). In this method, the coreduction of Ru and Ni was performed with the help of ultrasonic tip sonicator. Here, PVP was used as both stabilizing and reducing agents. The final mixture was brownish black, which indicates the reduction of 2+ and 3+ oxidation state of the metals to zero
Scheme 2. The general reaction set-up of the dehydrocoupling reaction of DMAB ((CH3)2 NHBH3) by using nanocatalysts.
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Fig. 1. (a) Transmission electron microscopy, high-resolution transmission electron microscopy, and size distribution (b) EELS mapping (c) EELS line profile of monodisperse Ru–Ni@PVP.
oxidation state and alloy nanoparticles were formed. As indicated Fig. 1, TEM results reveal the microstructural features, composition, and morphology of Ru-Ni@PVP nanomaterials. The mean size measured in this investigation was found to be around 3.51 ± 0.38 nm. HRTEM investigation result was also demonstrated in Fig. 1a and it can be seen from here that the nanoparticles were mostly spherical. No agglomeration was noticed in the TEM and HR-TEM analyses. Furthermore, HR-TEM results depicted the lattice fringes of 0.21 nm and this finding is the exact same value for the nominal Ru (1 0 1) spacing of 0.21 nm [57]. As shown in Fig. 1b and c, EELS mapping and line profile indicate the confirmation of the existence of both Ru and Ni at the same time in the prepared catalyst which indicates the formation of Ru-Ni alloy. The morphology and size of monodisperse Ru-Ni@PVP nanoparticles were investigated with x-ray diffraction technique. As a control experiment, XRD of PVP, Ru@PVP, and Ni@PVP was given in order to confirm the existence of Ru–Ni@PVP nanoparticles. As shown in Fig. 2, the mixture of Ru (1 0 1) and Ni (1 1 1) crystal
Fig. 2. XRD of PVP, Ru@PVP, Ni@PVP, and Ru–Ni@PVP nanoparticles.
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Fig. 3. (a) 2D and (b) 3D view of Ru 3p and (c) 2D and (d) 3D view of Ni 2p XPS spectra of Ru–Ni@PVP NPs.
plane in the prepared catalyst was easily observed at 44.2° which confirms the alloy formation of Ru-Ni@PVP nanocomposites [58]. The XPS technique was used to analyze the electronic structure and surface oxidation of the novel Ru-Ni@PVP nanocatalyst. The XPS spectra of the Ru 3p and Ni 2p regions of the nanocatalyst were given in Fig. 3. For the Ru 3p, two peaks can be recognized at 463.1 eV and 483.2 eV, which stand for the metallic state of Ru and some of the +3 oxidation state of Ru respectively. In addition, two other peaks identify Ni 2p spectra (2p1/2, 2p3/2) can be seen at 855.3 eV and 873.3 eV, respectively, which are directly related to Ni (0) and Ni (II), as illustrated in the Fig. 3c and d. This higher oxidation state of the Ru and Ni in the prepared catalyst is most probably due to the unreduced species and/or some of the oxidized species of Ru and Ni [59].
3.2. The dehydrocoupling of DMAB with the help of Ru–Ni@PVP nanomaterials In the present study, the stability and efficiency of monodisperse Ru–Ni@PVP nanoparticles were demonstrated for catalytic dehydrogenation of DMAB. As shown in Fig. 4a, various concentrations of monodisperse Ru–Ni@PVP nanoparticles against time were shown for dehydrogenation of DMAB at room temperature. A sudden hydrogen evolution starts linearly with no induction period and continues till the completion of catalytic dehydrogenation of DMAB. The conversion of (CH3)2NHBH3 to [(CH3)2NBH2]2 was demonstrated by NMR spectra (d = 12.7 ppm to d = 5 ppm, respectively) showing the complete dehydrogenation of DMAB as shown in Fig. S3 (in the production of 1.0 equivalent of H2) even at room temperature. Besides, the results of catalytic dehydrogena-
Fig. 4. (a) Plot of nH2/nDMAB vs time for dehydrocoupling of DMAB in the presence of Ru-Ni/PVP NPs with various concentrations of the catalyst at 25 ± 0.1 °C. (b) % conversion graph at different times for monodisperse Ru-Ni/PVP NPs (7.5% mol) catalyzed dehydrocoupling of DMAB in THF at various temperatures.
tion of DMAB with the help of monodisperse Ru–Ni@PVP nanoparticles were shown in the Fig. 4b in various temperatures such as 20, 25, 30 and 35 °C. The rate constants of hydrogen production at these four different temperatures were calculated using this figure during dehydrogenation of DMAB. With the help of Arrhenius and Eyring graph as shown in Fig. 5a and b, the Ea value (36.52 ± 3 kJ mol 1), the activation enthalpy (DH# = 34.02 ± 2 kJmol 1) and activation entropy (DS# = 84.47 Jmol 1K 1) were calculated. High negative values of activation entropy and small activation
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Fig. 5. (a) Arrhenius and (b) Eyring plot of monodisperse Ru-Ni/PVP NPs.
Table 1 Different catalysts, their turnover frequencies and conversion values for DMAB dehydrogenation.
*
Entry
(Pre) Catalysts
Conv. (%)
TOF
Solvent
Temperature (oC)
Ref
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
RuNi@PVP Cp2 Ti Trans RuMe2 (PMe)₄ [Cr (CO)₅ (thf)] [Rh (1,5-cod) m-Cl]2 [Rh Cl (PHCy2)3] [Rh (1,5-cod)2] Otf [Ir(1,5-cod) m-Cl]2 [Ru H (PMe3) (NC2H4PPr2)2] Pd/C Ir Cl3 Rh Cl3 Trans PdCl2 (P(o-tolyl)3)2 Rh Cl (PPh3)3 (Idipp) Cu Cl Pt(0)/TPA@AC [Rh (1,5-cod) (dmpe)] PF₆ [Cp *Rh (m-Cl) Cl]2 [Cr (CO)₅ (ɳ1-BH3NMe3)] PdCo @PVP PdNi@PEDOT Pd@GO H Rh (CO) (PPh3)3 Ni (skeletal) Pt(0)/BA Pt NPs@CBH Rh (0)/[Noct₄] Cl RuNiPt@GO Pt(0)/TBA RuCo@f -MWCNT [(C₅H3-1,3 (SiMe3)2)2 Ti]2 Pt@PANI-rGO PdNi@GO Pt(0)/AA
100 100 100 97 100 100 95 95 100 95 25 90 20 100 100 100 95 100 97 100 100 100 5 100 100 100 90 100 100 100 100 100 100 100
458.57 12.3 12.4 13.4 12.5 2.6 12.0 0.7 1.5 2.8 0.3 7.9 0.2 4.3 0.3 34.14 1.7 0.9 19.9 330 451.28 38.02 0.1 3.2 24.88 70.28 8.2 727 31.24 775.28 420.0 42.94 271.90 15.0
THF toluene THF THF THF hexane THF THF THF THF THF THF THF THF NI* THF THF THF benzene THF THF THF THF Bis(2-methoxyethyl) ether THF THF THF THF THF THF THF THF THF THF
25 20 25 65 25 70 25 25 25 25 25 25 25 25
This study 26 22 44 22 33 22 22 15 22 22 22 22 22 42 30 22 21 44 43 45 46 22 54 50 47 22 49 50 55 52 36 56 34
25 25 25 25 25 25 25 25 60 25 25 25 25 25 25 25 25 25 25
No information.
enthalpy values refer to an associate mechanism in the catalytic dehydrocoupling of DMAB. Briefly, it is important to say that H2 gas (1 mol of H2 per 1 mol of DMAB) was released completely within a very short time when Ru–Ni@PVP nanoparticles were used. The TOF number was found to be 458.57 h 1 at 25 ± 0.1 °C. As shown in Table 1, the monodisperse Ru–Ni@PVP nanoparticles became one of the best catalytic activity (TOF value = 458.57 h 1) for dehydrocoupling of DMAB compared to others in the literature. In addition, some comparative studies were carried out; the catalytic performances of Ru@PVP
and Ni@PVP nanoparticles, physically mixed Ru@PVP–Ni@PVP nanomaterials, and Ru–Ni@PVP alloy nanomaterials were examined, and the alloy characteristic structure of Ru-Ni@PVP nanoparticles was proved. For this purpose, in these investigations, the turnover frequencies (TOFs) for Ni@PVP nanoparticles, Ru@PVP nanoparticles, physically mixed Ru@PVP–Ni@PVP nanoparticles and newly synthesized Ru-Ni@PVP bimetallic nanoparticles were calculated. The higher TOF value of the Ru-Ni@PVP nanoparticles compared to the other prepared ones indicates the alloy character of prepared nanocomposites. Besides, as control experiments
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shown in Fig. S4, the precursor materials of Ru and Ni were performed for dehydrocoupling of DMAB but it wasn’t observed the complete conversion of DMAB with the help of those materials. In conclusion, monodisperse Ru–Ni@PVP nanoparticles are very promising, isolable and reusable nanocatalysts for dehydrocoupling of DMAB. In the prepared catalyst, as PVP generated enough stability and possible synergistic and cooperative relationship between Ru and Ni, our system supplied outstanding catalytic performance towards the dehydrocoupling of DMAB. Additionally, the reusability performance of PVP-stabilized Ru-Ni nanoparticles for the hydrogenation reaction of DMAB was investigated and the results were given in Fig. S5; the nanoparticles maintain their initial performance until the 4th experiment without any significant reduction. 78% of the initial performance of the monodisperse Ru-Ni@PVP was observed for dehydrocoupling of DMAB. This decrease can be explained by the increase in the amount of product, the reduction of the surface area of the nanoparticles, which reduces the availability of catalytically active sites and the accumulation of nanoclusters (Fig. S5). By the way, even after the 4th cycle, the catalyst maintained its own content without any leaching. 4. Conclusions In summary, PVP-stabilized ruthenium-nickel nanomaterials were synthesized and their analytical investigations and usage for catalytic dehydrogenation of DMAB were performed in this study. The most important points from the study were given below: Since the materials containing OH ligands are much more favorable for the formation of small NPs on the supports than those without OH ligands, a facile sodium- hydroxideassisted reduction method was performed to prepare Ru-Ni@PVP nanomaterials. In this method, ruthenium and nickel salts were co-reduced in the presence of PVP. Ultrasonication was utilized to augment the dispersion. The results indicated that the method is very efficient to get monodisperse Ru– Ni nanoparticles on PVP without any agglomeration problem. The prepared nanocomposites were characterized by TEM, HRTEM, XRD, and XPS and performed as a catalyst for dehydrocoupling of dimethylamine-borane (DMAB). The results indicate the alloy formation of Ru and Ni in the presence of PVP in the prepared catalyst. Ru–Ni@PVP nanoparticles showed the outstanding catalytic performance for dehydrocoupling of DMAB. The one of the best catalytic efficiency was obtained as shown in Table 1. Ea value (36.52 ± 3 kJmol 1), the activation enthalpy (DH# = 34. 02 ± 2 kJmol 1) and activation entropy (DS# = 84.47 Jmol 1K 1) were calculated by using Arrhenius and Eyring plots. High negative values of activation entropy and small activation enthalpy values refer to an associate mechanism in the catalytic dehydrocoupling of DMAB. 78% of the initial performance of the monodisperse Ru-Ni@PVP was observed for dehydrocoupling of DMAB even after the 4th cycle. In near future, monodisperse Ru–Ni@PVP nanoparticles have promising and great potential to generate hydrogen gas in fuel cells via catalytic dehydrocoupling of DMAB.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.jcis.2018.05.021.
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References [1] D.A.J. Rand, R.M. Dell, The hydrogen economy: a threat or an opportunity for lead-acid batteries?, J Power Sources 144 (2005) 568–578. [2] Q. Zhang, G.M. Smith, Y. Wu, Catalytic hydrolysis of sodium borohydride in an integrated reactor for hydrogen generation, Int. J. Hydrogen Energy 32 (2007) 4731–4735. [3] Basic Research Needs For the Hydrogen Economy, Report of the basic energy sciences workshop on Hydrogen production, storage and use, May 13–15, Office of Science, U.S. Department of Energy, 2003. www.sc.doe.gov/bes/ hydrogen.pdf. [4] J. Lee, K.Y. Kong, C.R. Jung, E. Cho, S.P. Yoon, J. Han, T.G. Lee, S.W. Nam, A structured Co-B catalyst for hydrogen extraction from NaBH4 solution, Catal. Today 120 (2007) 305–310. [5] S.C. Amendola, J.M. Janjua, N.C. Spencer, M.T. Kelly, P.J. Petillo, S.L. SharpGoldman, M. Binder, A safe, portable, hydrogen gas generator using aqueous borohydride solution and Ru catalyst, Int. J. Hydrogen Energy 25 (2000) 969– 975. [6] F.H. Stephens, V. Pons, R.T. Baker, Ammonia-borane: the hydrogen source par excellence, Dalton Trans. 25 (2007) 2613–2626. [7] N. Mohajeri, A. T-Raissi, O. Adebiyi, Hydrolytic cleavage of the ammoniaborane complex for hydrogen production, J. Power Sources 167 (2007) 482– 485. [8] P.V. Ramachandran, P.D. Gagare, Preparation of ammonia borane in high yield and purity, methanolysis, and regeneration, Inorg. Chem. 46 (2007) 7810– 7817. [9] Q. Xu, M. Chandra, Catalytic activities of non-noble metals for hydrogen generation from aqueous ammonia–borane at room temperature, J. Power Sources 163 (2006) 364–370. [10] Q. Xu, M. Chandra, A portable hydrogen generation system, catalytic hydrolysis of ammonia–borane, J. Alloys Compd. 446–447 (2007) 729–732. [11] T. Umegaki, J.M. Yan, X.B. Zhang, H. Shioyama, N. Kuriyama, Q. Xu, Preparation and catalysis of poly(N-vinyl-2-pyrrolidone) (PVP) stabilized nickel catalyst for hydrolytic dehydrogenation of ammonia borane, Int. J. Hydrogen Energy 34 (2009) 3816–3822. [12] T. Umegaki, J.M. Yan, X.B. Zhang, H. Shioyama, N. Kuriyama, Q. Xu, Hollow NieSiO2 nanosphere-catalyzed hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage, J. Power Sources 191 (2009) 209– 216. [13] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Iron-nanoparticle-catalyzed hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage, Angew. Chem. Int. Ed. 47 (2008) 2287–2289. [14] R. Fernandes, N. Patel, A. Miotello, Hydrogen generation by hydrolysis of the alkaline NaBH4 solution with Cr-promoted Co–B amorphous catalyst, Appl. Catal. B 92 (2009) 68–74. [15] A. Friederich, M. Drees, S. Schneider, Ruthenium-catalyzed dimethylamineborane dehydrogenation, stepwise metal-centered dehydrocyclization, Chem. Eur. J. 15 (2009) 10339–10342. [16] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Room temperature hydrolytic dehydrogenation of ammonia borane catalyzed by Co nanoparticles, J. Power Sources 195 (2010) 1091–1094. [17] J.M. Yan, X.B. Zhang, S. Han, H. Shioyama, Q. Xu, Synthesis of longtime water/ air-stable Ni nanoparticles and their high catalytic activity for hydrolysis of ammonia borane for hydrogen generation, Inorg. Chem. 48 (2009) 7389– 7393. [18] D.G. Tong, X.L. Zeng, W. Chu, D. Wang, P. Wu, Magnetically recyclable hollow Co–B nanospindles as catalysts for hydrogen generation from ammonia borane, J. Mater. Sci. 45 (2010) 2862–2867. [19] N. Patel, R. Fernandes, G. Guella, A. Miotello, Nanoparticle-assembled Co-B thin film for the hydrolysis of ammonia borane: a highly active catalyst for hydrogen production, Appl. Catal. B 95 (2010) 137–143. [20] Y. Yamada, K. Yano, Q. Xu, S. Fukuzumi, Cu/Co3O4 nanoparticles as catalysts for hydrogen evolution from ammonia borane by hydrolysis, J. Phys. Chem. C 114 (2010) 16456–16462. [21] C.A. Jaska, K. Temple, A.J. Lough, I. Manners, Transition metal-catalyzed formation of boron nitrogen bonds: catalytic dehydrocoupling of amineborane adducts to form amino boranes and borazines, J. Am. Chem. Soc. 125 (2003) 9424–9434. [22] C.A. Jaska, I. Manners, Heterogeneous or homogeneous catalysis? mechanistic studies of the rhodium-catalyzed dehydrocoupling of amine-borane and phosphine-borane adducts, J. Am. Chem. Soc. 126 (2004) 9776–9785. [23] Y. Chen, J.L. Fulton, J.C. Linehan, T. Autrey, In situ spectroscopic studies of the rhodıum catalyzed production of hydrogen from dimethylamıne borane homogeneous or heterogeneous catalysis, Prepr. Pap. Am. Chem. Soc. Div. Fuel Chem. 49 (2004) 972–973. [24] Y. Chen, J.L. Fulton, J.C. Linehan, T. Autrey, In Situ XAFS and NMR Study of Rhodium-Catalyzed dehydrogenation of dimethylamine borane, J. Am. Chem. Soc. 127 (2005) 3254–3255. [25] T.J. Clark, C.A. Russell, I. Manners, Homogeneous, Titanocene-catalyzed dehydrocoupling of amine borane adducts, J. Am. Chem. Soc. 128 (2006) 9582–9583. [26] M.E. Sloan, A. Staubitz, T.J. Clark, C.A. Russell, G.C. Lloyd-Jones, I. Manners, Homogeneous catalytic dehydrocoupling/dehydrogenation of amine borane adducts by the early transition metal, group 4 metallocene complexes, J. Am. Chem. Soc. 132 (2010) 3831–3841.
486
B. Sen et al. / Journal of Colloid and Interface Science 526 (2018) 480–486
[27] G. Alcaraz, L. Vendier, E. Clot, S. Sabo-Etienne, Ruthenium Bis(r-B-H) aminoborane complexes from dehydrogenation of amine–boranes, Trapping of H2B-NH2, Angew. Chem. Int. Ed. 49 (2010) 918–920. [28] Y. Yildiz, E. Erken, H. Pamuk, F. Sen, Monodisperse Pt nanoparticles assembled on reduced graphene oxide: highly efficient and reusable catalyst for methanol oxidation and dehydrocoupling of dimethylamine-borane (DMAB), J. Nanosci. Nanotechnol. 16 (2016) 5951–5958. [29] B. Çelik, G. Basßkaya, Ö. Karatepe, E. Erken, F. Sßen, Monodisperse Pt(0)/DPA@GO nanoparticles as highly active catalysts for alcohol oxidation and dehydrogenation of DMAB, Int. J. Hydrogen Energy 41 (2016) 5661–5669. [30] B. Çelik, E. Erken, S. Erisß, Y. Yıldız, B. S ß ahin, H. Pamuk, F. Sen, Highly monodisperse Pt(0)@AC NPs as highly efficient and reusable catalysts: the effect of the surfactant on their catalytic activities in room temperature dehydrocoupling of DMAB, Catal. Sci. Tech. 6 (2016) 1685–1692. [31] Y. Jiang, H. Berke, Dehydrocoupling of dimethylamine-borane catalyzed by rhenium complexes and its application in olefin transfer-hydrogenations, Chem. Commun. 34 (2007) 3571–3573. [32] J.L. Fulton, J.C. Linehan, T. Autrey, M. Balasubramanian, Y. Chen, N.K. Szymczak, When is a nanoparticle a cluster? an operando EXAFS study of amine borane dehydrocoupling by Rh4-6 Clusters, J. Am. Chem. Soc. 129 (2007) 11936– 11949. [33] M.E. Sloan, T.J. Clark, I. Manners, Homogeneous catalytic dehydrogenation/ dehydrocoupling of amine-borane adducts by the Rh(I) Wilkinson’s complex analog RhCl(PHCy2)3 (Cy = cyclohexyl), Inorg. Chem. 48 (2009) 2429–2435. [34] F. Sen, Y. Karatasß, M. Gülcan, M. Zahmakıran, Amylamine stabilized platinum (0) nanoparticles: active and reusable nanocatalyst in the room temperature dehydrogenation of dimethylamine-borane, RSC Adv. 4 (4) (2014) 1526–1531. [35] M. Munoz-Olasagasti, A. Telleria, J. Perez-Miqueo, M.A. Garralda, Z.A. Freixa, A readily accessible ruthenium catalyst for the solvolytic dehydrogenation of amine-borane adducts, Dalton Trans. 43 (2014) 11404–11409. [36] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Polymer-Graphene hybrid decorated Pt nanoparticles as highly efficient and reusable catalyst for the dehydrogenation of dimethylamine-borane at room temperature, Int. J. Hydrogen Energy 42 (36) (2017) 23284–23291. [37] Z.S. Yang, J.J. Wu, Pd/Co bimetallic nanoparticles: coelectrodeposition under the protection of PVP and enhanced electrocatalytic activity for ethanol electrooxidation, Fuel Cells 12 (2012) 420. [38] R. Wang, S. Liao, S. Ji, High-performance Pd-based catalysts for oxidation of formic acid, J. Power Sources 180 (2008) 205. [39] C. Jung, C.M. Sanchez-Sanchez, C.L. Lin, J. Rodriguez-Lopez, A.J. Bard, The electrocatalytic activity of Pd_Co bimetallic mixtures for formic acid oxidation studied by scanning electrochemical microscopy, Anal. Chem. 81 (2009) 7003. [40] M. Yin, Q. Li, J.O. Jensen, Y. Huang, L.N. Cleemann, N.J. Bjerrum, W. Xing, Tungsten carbide promoted Pd and Pd-Co electrocatalysts for formic acid electrooxidation, J. Power Sources 219 (2012) 106. [41] X. Wang, Y. Xia, The electrocatalytic performance of PdCo-C catalyst for formic acid oxidation, Electrochem. Commun. 10 (2008) 1644. [42] R.J. Keaton, J.M. Blacquiere, R.T. Baker, Base metal catalyzed dehydrogenation of ammonia borane for chemical hydrogen storage, J. Am. Chem. Soc. 129 (7) (2007) 1844–1845. [43] B. Celik, Y. Yildiz, H. Sert, E. Erken, Y. Koskun, F. Sen, Monodispersed palladium-cobalt alloy nanoparticles assembled on poly(N-vinylpyrrolidone) (PVP) as a highly effective catalyst for dimethylamine borane (DMAB) dehydrocoupling, RSC Adv. 6 (2016) 24097–24102.
[44] Y. Kawano, M. Uruichi, M. Shiomi, S. Taki, T. Kawaguchi, T. Kakizawa, H. Ogino, Dehydrocoupling reactions of borane secondary and primary amine adducts catalyzed by group-6 carbonyl complexes: formation of aminoboranes and borazines, J. Am. Chem. Soc. 131 (2009) 14946. [45] B. Sen, S. Kuzu, E. Demir, E. Yildirir, F. Sen, Highly efficient catalytic dehydrogenation of dimethyl ammonia borane via monodisperse palladiumnickel alloy nanoparticles assembled on PEDOT, Int. J. Hydrogen Energy 42 (36) (2017) 23307–23314. [46] B. Sen, A. Aygün, T. Onal Okyay, A. Savk, R. Kartop, F. Sen, Monodisperse palladium nanoparticles assembled on graphene oxide with the high catalytic activity and reusability in the dehydrogenation of dimethylamine-borane, Int. J. Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.03.175. [47] B. Sen, A. Savk, F. Sen, Highly efficient monodisperse nanoparticles confined in the carbon black hybrid material for hydrogen liberation, J. Colloid Interf. Sci. 520 (2018) 112–118. [48] X. Yang, F. Cheng, J. Liang, Z. Tao, J. Chen, PtxNi1 x nanoparticles as catalysts for hydrogen generation from hydrolysis of ammonia borane, Int. J. Hydrogen Energy 34 (2009) 8785–8791. [49] B. Sen, S. Kuzu, E. Demir, T. Onal Okyay, F. Sen, Hydrogen liberation from the dehydrocoupling of dimethylamine-borane at room temperature by using novel and highly monodispersed RuPtNi nanocatalysts decorated with graphene oxide, Int. J. Hydrogen Energy 42 (36) (2017) 23299–23306. [50] E. Erken, H. Pamuk, O. Karatepe, G. Baskaya, H. Sert, O.M. Kalfa, F. Sen, New Pt (0) nanoparticles as highly active and reusable catalysts in the C1–C3 alcohol oxidation and the room temperature dehydrocoupling of DimethylamineBorane (DMAB), J. Cluster Sci. 27 (9) (2016) 23. [51] B. Celik, S. Kuzu, E. Erken, H. Sert, Y. Koskun, F. Sen, Nearly monodisperse carbon nanotube furnished nanocatalysts as highly efficient and reusable catalyst for dehydrocoupling of DMAB and C1 to C3 alcohol oxidation, Int. J. Hydrogen Energy 41 (2016) 3093–3101. [52] D. Pun, E. Lobkovsky, P.J. Chirik, Amine-borane dehydrogenation promoted by isolable zirconium sandwich, titanium sandwich, and N2 complexes, Chem. Commun. 44 (2007) 3297. [53] R.J. Keaton, J.M. Blacquiere, R.T. Baker, Base metal catalyzed dehydrogenation of ammonia borane for chemical hydrogen storage, J. Am. Chem. Soc. 129 (2007) 11936. [54] A.P.M. Robertson, R. Suter, L. Chabanne, G.R. Whittel, I. Manners, Heterogeneous dehydrocoupling of amine-borane adducts by skeletal nickel catalysts, Inorg. Chem. 50 (2011) 12680. [55] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Highly monodisperse RuCo nanoparticles decorated on functionalized multiwalled carbon nanotube with the highest observed catalytic activity in the dehydrogenation of dimethylamine borane, Int. J. Hydrogen Energy 42 (36) (2017) 23292–23298. [56] B. Sen, S. Kuzu, E. Demir, S. Akocak, F. Sen, Monodisperse palladium-nickel alloy nanoparticles assembled on graphene oxide with the high catalytic activity and reusability in the dehydrogenation of dimethylamine-borane, Int. J. Hydrogen Energy 42 (36) (2017) 23276–23283. [57] D.B. Williams, C.B. Carter, Transmission Electron Microscopy A Textbook for Materials Science, first ed., Springer, 1996. [58] H.P. Klug, L.E. Alexander, X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials, second ed., Wiley, 1974. [59] P. Van der Heide, -ray Diffraction Procedures for Polycrystalline and Amorphous Materials, first ed., John Wiley & Sons, Inc., 2012.