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Pd nanoparticles supported on MIL-101 as high-performance catalysts for catalytic hydrolysis of ammonia borane
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 4 9 4 7 e4 9 5 3
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Short Communication
Pd nanoparticles supported on MIL-101 as highperformance catalysts for catalytic hydrolysis of ammonia borane Hongmei Dai a, Jun Su c, Kai Hu a, Wei Luo a,b,*, Gongzhen Cheng a a
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, PR China Suzhou Institute of Wuhan University, Suzhou, Jiangsu 215123, PR China c Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China b
article info
abstract
Article history:
Well dispersed ultrafine Pd NPs have been immobilized in the framework of MIL-101, and
Received 17 December 2013
tested for the catalytic hydrolysis of ammonia borane. The powder XRD, N2 adsorptione
Received in revised form
desorption, TEM, and ICP-AES were employed to characterize the Pd@MIL-101 catalyst. The
11 January 2014
as-synthesized Pd@MIL-101 exhibit the highest catalytic activity toward hydrolysis of AB
Accepted 12 January 2014
among the Pd-based nano-catalysts ever reported, with the TOF value of 45 mol H2 min1
Available online 12 February 2014
(mol Pd)1. Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
Keywords:
reserved.
MIL-101 Palladium Ammonia borane Hydrogen storage
1.
Introduction
One of the challenges of 21st century is to develop and sustain a carbon-neutral economy in place of the current prevalent petroleum economy. Hydrogen, producing only water as a byproduct, has been considered to be the most promising solution for alternative energy applications [1]. However, one of the most application obstacles is the safe and efficient storage of hydrogen [2]. Various hydrogen storage approaches
are currently being investigated, including metal hydrides [3], sorbent materials [4], and chemical hydride systems [5]. Boron, nitrogen containing compounds have attracted much attention because of their high gravimetric hydrogen densities and favorable kinetics of hydrogen release [6]. Ammonia borane (NH3eBH3, AB) has recently received a great interest, because of its 19.6 wt% hydrogen content, high stability, and environmental benignity [7]. The hydrogen stored in AB can be released through different ways [8], but the hydrolysis of AB using transition metal catalysts at ambient conditions seems
* Corresponding author. College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, PR China. Tel.: þ86 2787467716. E-mail address: [email protected] (W. Luo). 0360-3199/$ e see front matter Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2014.01.068
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to be the most convenient route for the portable applications [9]. So far, many catalyst systems have been tested for hydrogen generation from the hydrolysis of AB, however, the optimal compromise between costs, efficiency and recyclability are still remains considerable challenges. On the other hand, due to the high specific surface area and tunable pore size, metal-organic frameworks (MOFs) have attracted growing attention in the application of gas sorption and storage [10], drug delivery [11], and molecular separation [12]. Given the similarity to zeolites, loading of metal nanoparticles (NPs) inside the porous materials of MOFs could afford solid catalysts. The porous structures of MOFs could restrain the aggregation of the metal NPs, and further affect the catalytic activity and recyclability of the catalysts. Loading of metal NPs into the porous of MOFs is of current interest [13]. So far, to the best of our knowledge, there have been only about two examples concerning Pt@MIL-101 [14], and Ni@ZIF8 [13b] for catalytic hydrolysis of ammonia borane. Herein, we reported the generation of highly dispersed Pd NPs immobilized in MIL-101. MIL-101 with two cavities of ca. 2.9 and 3.4 nm free diameters accessible through two pore windows of ca. 1.2 and 1.6 nm, was chosen because of its extra high specific surface area, high thermal stability (up to 300 C), and high chemical stability to water [15]. The catalytic hydrolysis of ammonia borane of the as-synthesized Pd@MIL101 was studied. Compared with other reported Pd-based catalysts, the Pd@MIL-101 exhibits the highest catalytic activity toward hydrolysis of ammonia borane at ambient temperature.
2.
Experimental
2.1.
Chemicals and materials
All chemicals were commercial and used without further purification. Chromic nitrate nonahydrate (Cr(NO3)3$9H2O, Sinopharm Chemical Reagent Co., Ltd., 99%), aqueous hydrofluoric acid (HF, Sinopharm Chemical Reagent Co., Ltd., 40%), ammonium fluoride (NH4F, Sinopharm Chemical Reagent Co., Ltd., 96%), hydrochloric acid (HCl, Sinopharm Chemical Reagent Co., Ltd., 37%), palladium chloride (PdCl2, Wuhan Greatwall Chemical Co., Ltd., 99%), terephthalic acid (HO2CC6H4CO2H, Sinopharm Chemical Reagent Co., Ltd., 99%), sodium borohydride (NaBH4, Sinopharm Chemical Reagent Co., Ltd, 96%),ammonia borane(NH3BH3, Aldrich, 97%), ethanol (C2H5OH, Sinopharm Chemical Reagent Co., Ltd., >99.8%) were used as received. We use ordinary distilled water as the reaction solvent.
2.2.
Synthesis of MIL-101
MIL-101 was synthesized using the reported procedure [16]. Terephthalic acid (332 mg, 2.0 mmol), Cr(NO3)3$9H2O (800 mg, 2.0 mmol), aqueous HF (0.1 mL, 40 wt%) and de-ionized water (9.6 mL) were placed in a 50 mL Teflon-liner autoclave and heated at 220 C for 8 h. After natural cooling, the resulting green powder of MIL-101 with formula Cr3F(H2O)2O[(O2C) C6H4(CO2)]3$nH2O (n 25) was doubly filtered off using two glass filters with pore sizes of 40 mm to eliminate the
unreacted crystals of terephthalic acid, and then further purified by solvothermal treatment in ethanol at 80 C for 24 h. The resulting green solid was soaked in NH4F (1 M) solution at 70 C for 24 h to eliminate the terephthalic acid inside the pores of MIL-101 and immediately filtered resulting green solid was finally dried overnight at 150 C under vacuum for further use.
2.3.
Synthesis of H2PdCl4
A solution of tetrachloropalladinic acid (0.01 M, H2PdCl4) was prepared by mixing 44.5 mg of PdCl2 into 25 mL of HCl (0.02 M) aqueous solution under stirring at room temperature until complete dissolution.
2.4.
Synthesis of Pd@MIL-101
Activated MIL-101 (100 mg) was mixed with 10 mL de-ionized water containing (0.01, 0.02, 0.03, 0.04) mmol H2PdCl4 for 24 h, kept the reaction at 35 C and pH ¼ 3.0. The solid was centrifuged and washed with de-ionized water and ethanol. The resulting mixture was then reduced with sodium borohydride (NaBH4, 0.0378 g) at 273 K for 3 h to yield Pd@MIL-101.
2.5.
Hydrolytic dehydrogenation of ammonia borane
A mixture of 50 mg Pd@MIL-101 and 5 mL de-ionized water were kept in a two-necked round-bottom flask. One neck was connected to a pressure-equalization funnel to introduce 3 mL aqueous solution of NH3BH3 (30.8 mg, 1 mmol), and the other neck was connected to a gas burette to monitor the volume of the gas evolution. The reaction started when the aqueous solution was added to the palladium catalyst, and the evolution of gas was monitored using the gas burette. The reactions were carried out at 298 K in air.
2.6. In situ generation of the Pd(0) catalyst and hydrolysis of ammonia borane 1.89 mL solution of H2PdCl4 (0.01 M) was kept in a two-necked round-bottom flask. First introduce 3 mL aqueous solution of NaBH4 (37.8 mg, 1 mmol) to reduce Pd2þ to Pd0, after the hydrogen generation reaction was completed, another equivalent of NH3BH3 (30.8 mg, 1 mmol) was added into the reaction flask. The evolution of gas was monitored by the gas burette. The reactions were carried out at 298 K in air.
2.7. 101
Hydrolysis of ammonia borane catalyzed by MIL-
Except for the replacement of 50 mg Pd@MIL-101 by 50 mg activated MIL-101, the experiment procedures were similar to that of Pd@MIL-101.
2.8.
Reusability test
3 mL of solution containing 30.8 mg AB was added to 5 mL of water dissolved 50 mg 4 wt% Pd@MIL-101, the evolution of gas was monitored as described above. After the hydrogen generation reaction was completed, new aqueous AB solution
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Fig. 1 e (a, b) Low-angle and wide-angle Powder X-ray diffraction patterns of samples: (a) MIL-101; (b) activated MIL-101; (c) 0.74 wt% Pd@MIL-101; (d) 1.5 wt% Pd@MIL-101; (e) 4wt% Pd@MIL-101; (f) 4 wt% Pd@MIL-101 after five runs of catalytic hydrolysis of AB.
(30.8 mg, 3 mL) was added into the reaction flask. The evolution of gas was monitored using the gas burette. Such cycle tests of the catalyst for the hydrolysis of AB were carried out four times in air.
2.9.
Characterization
The morphologies and sizes of the samples were observed by using a Tecnai G20 U-Twin transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) at an acceleration voltage of 200 kV. Powder X-ray diffraction (XRD) patterns were measured by a Bruker D8Advance X-ray diffractometer using Cu Ka radiation source (l ¼ 0.154178 nm) with a velocity of 1 min1. X-ray photoelectron spectroscopy (XPS) measurement was performed with a Kratos XSAM 800 spectrophotometer. The surface area measurements were performed with N2 adsorption/desorption isotherms at liquid nitrogen temperature (77 K) after dehydration under vacuum at 150 C for 12 h using Quantachrome NOVA 4200e. The inductively coupled plasmaatomic emission spectroscopy (ICP-AES) was performed on IRIS Intrepid II XSP (Thermo Fisher Scientific, USA).
3.
PXRD (Fig. 1b), in which a peak at 40.1 corresponding to the Pd(111) is found, confirming the existence of Pd in the framework of MIL-101. The N2 adsorptionedesorption isotherms of MIL-101 and Pd@MIL-101 were shown in Fig. 2. The specific areas of MIL-101, 0.74 wt% Pd@MIL-101, and 4 wt% Pd@MIL-101 were 2081, 1724 and 1603 m2/g respectively [17]. The large decrease in the amount of N2 adsorption and the pore volume [18] (Fig. S1, Table S1) of Pd@MIL-101 indicates that Pd NPs were well dispersed to the frameworks of MIL-101. In the X-ray photoelectron spectroscopy (XPS) (Fig. S2), the 3d5/2 and 3d3/2 peaks of Pd0 [19] appear at 335.2 and 340.5 eV, and no obvious peak of Pd2þ is observed. The morphologies of MIL-101 immobilized Pd NPs were further characterized by transmission electron microscopic (TEM) and energy-dispersive X-ray spectroscopy (EDX) measurements. TEM images of 4 wt%, and 1.46 wt% Pd@MIL-101 (Fig. 3a, b, e and f) indicate that the Pd NPs are well dispersed, and encapsulated in the cages of the MIL-101. The EDX spectra (Fig. 3g and h) confirm the presence of Pd. The
Results and discussion
MIL-101 was synthesized according to the literature [16]. The unreacted terephthalic acid in the pores were removed by solvothermally treated with ethanol and aqueous NH4F solution respectively. The supported Pd@MIL-101 catalyst was prepared through solution infiltration of activated MIL-101 with H2PdCl4 at pH ¼ 3.0, followed by treatment with NaBH4. The low-angle powder X-ray diffractions (PXRD) of the assynthesized MIL-101, activated MIL-101, Pd@MIL-101 with different Pd loadings up to 4 wt%, and the 4 wt% Pd@MIL-101 after the five cycle hydrolysis of AB exhibit no loss of crystallinity (Fig. 1a), indicating that the integrity of the MIL-101 framework is maintained well during the catalyst preparation and catalytic process. Furthermore, from the wide-angle
Fig. 2 e N2 sorption isotherms of (a) activated MIL-101; (b) 0.74 wt% Pd@MIL-101; (c) 4 wt% Pd@MIL-101 at 77 K. Filled and open symbols represent adsorption and desorption branches, respectively.
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Fig. 3 e (a, b) TEM images of 4 wt% Pd@MIL-101reduced by sodium borohydride; (c, d) TEM images of 4 wt% Pd@MIL-101 after five runs of catalytic hydrolysis of AB; (e, f) TEM images of 1.46 wt% Pd@MIL-101; (g) EDX of 4 wt% Pd@MIL-101; (h) EDX of 1.46 wt% Pd@MIL-101.
mean diameter of Pd NPs in 4 wt% Pd@MIL-101 was in the range of 1.4e1.8 nm, with a mean diameter of 1.8 0.4 nm (Fig. S3), which are small enough to be immobilized into the mesoporous cavities of MIL-101. These results indicate that the ultrafine Pd NPs have been effectively immobilized by MIL101, which result in the high catalytic activity and durability for hydrolysis of AB (vide infra). The catalytic activity of Pd@MIL-101 toward hydrolysis of AB were studied. Fig. 4 shows the H2 generation from aqueous AB at ambient conditions in the present of Pd@MIL-101. Among the catalysts of Pd@MIL-101 with different Pd loadings (4.0 wt%, 2.7 wt%, 1.5 wt%, 0.7 wt%, determined by ICPAES, Table S2), the 4 wt% Pd@MIL-101 has the highest activity, with the TOF value of 45 mol H2 min1 (mol Pd)1. Furthermore, as the control experiment, the same amount of Pd NPs reduced by NaBH4 without MIL-101, and MIL-101
without Pd loading were synthesized and applied to hydrolysis of AB, as shown in Fig. S4, only 2.5 equiv. H2 were released for more than 40 min for Pd NPs, and almost no reactivity for MIL-101 toward hydrolysis of AB at room temperature. Moreover, it can be seen from Table 1, the 4 wt% Pd@MIL-101 catalysts exhibit the highest TOF value for catalytic hydrolysis of AB among the Pd-based nano-catalysts ever reported, which confirms the cooperative effect between MIL-101 and Pd NPs. The durability of the catalyst is crucial in the practical application. The durability of 4 wt% Pd@MIL-101 catalyst for hydrolysis of AB was tested by adding another equivalents of aqueous AB solution after the hydrogen generation reaction was complete. As shown in Fig. S5, even after the 5th run, the catalyst still maintained the initial catalytic activity, indicating the Pd NPs have been effectively immobilized in the framework of MIL-101. The representative TEM images of 4 wt
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4951
Foundation of Ministry of Education of China (20120141120034), the Natural Science Foundation of Jiangsu Province (BK20130370), the Natural Science Foundation of Hubei Province (2013CFB288) and Large-scale Instrument and Equipment Sharing Foundation of Wuhan University.
Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.ijhydene.2014.01.068.
Fig. 4 e Hydrogen generation from aqueous AB in the presence of Pd@MIL-101 catalysts at room temperature. Pd/ AB (molar ratio) [ 0.0033, 0.007, 0.0125 and 0.0189 at Pd loadings of 0.74, 1.46, 2.67, and 4.0 wt%.
Table 1 e Catalytic activity of palladium nanoparticle with different support. Catalyst
Metal/AB ratio (mol/ mol)
TOF (molH2 molcatalyst1 min1)
Ref.
0.024
35.7
[20]
0.024 0.006 0.02 0.02 0.025 0.05 0.04 0.02 0.005 0.03 0.0189
22.7 26.3 6.25 5 1.39 0.67 6.25 40.89 15.55 19.1 45
[20] [21] [22] [23] [24] [25] [26] [27] [28] [29] This study
Co35Pd65/C annealed 25 wt% Co35Pd65/C 2.1 wt% RGO@Pd Pd/zeolite PSSA-co-MA-Pd 2 wt% Pd/r-Al2O3 Pd black RGO@Pd [email protected] 2.1wt%CDG-Pd PdePVBeTiO2 4wt%Pd@MIL-101
% Pd@MIL-101 catalyst after the fifth run durability test were shown in Fig. 1c and d. There is no noticeable change in the morphology of the catalyst, indicating that the MIL-101 can stabilize Pd NPs for good durability.
4.
Conclusion
In summary, we have developed a facile method for immobilizing ultrafine Pd NPs into the frameworks of MIL-101, which exhibit highly catalytic activity and durability for catalytic hydrolysis of AB at ambient conditions. This is the first example for MOF-supported Pd catalysts for catalytic hydrolysis of AB. This simple synthetic method can be extended to other MOFs supported metal NP systems for more applications.
Acknowledgments This work was financially supported by the National Natural Science Foundation of China (21201134), the Ph.D Programs
references
[1] (a)Leitao EM, Jurca T, Manners I. Catalysis in service of main group chemistry offer a versatile approach to p-block molecules and materials. Nat Chem 2013;5:817e29; (b)Dalebrook AF, Gan WJ, Grasemann M, Moret S, Laurenczy G. Hydrogen storage: beyond conventional methods. Chem Commun 2013;49:8735e51; (c)Yang J, Sudik A, Wolvertonb C, Siegel DJ. High capacity hydrogen storage materials: attributes for automotive applications and techniques for materials discovery. Chem Soc Rev 2010;39:656e75; (d)Ma SQ, Zhou HC. Gas storage in porous metaleorganic frameworks for clean energy applications. Chem Commun 2010;46:44e53. [2] (a)Schlapbach L, Zu¨ttel A. Hydrogen-storage materials for mobile applications. Nature 2001;414:354e8; (b)Chen P, Xiong ZT, Luo JZ, Lin JY, Tan KL. Interaction of hydrogen with metal nitrides and imides. Nature 2002;420:302e4; (c)Orimo S, Nakamori Y, Eliseo JR, Zu¨ttel A, Jensen CM. Complex hydrides for hydrogen storage. Chem Rev 2007;107:4111e32. [3] Graetz J. New approaches to hydrogen storage. Chem Soc Rev 2009;38:73e82. [4] Suh MP, Park HJ, Prasad TK, Lim DW. Hydrogen storage in metal organic frameworks. Chem Rev 2012;112:782e835. [5] Staubitz A, Robertson APM, Manners I. Ammonia-borane and related compounds as dihydrogen sources. Chem Rev 2010;110:4079e124. [6] (a)Luo W, Campbell PG, Zakharov LN, Liu SY. A singlecomponent liquid-phase hydrogen storage material. J Am Chem Soc 2011;133:19326e9; (b)Huang Z, Autrey T. Boronenitrogenehydrogen (BNH) compounds: recent developments in hydrogen storage, applications in hydrogenation and catalysis, and new syntheses. Energy Environ Sci 2012;5:9257e68; (c)Hamilton CW, Baker RT, Staubitzc A, Manners I. BeN compounds for chemical hydrogen storage. Chem Soc Rev 2009;38:279e93. [7] (a)Yadav M, Xu Q. Liquid-phase chemical hydrogen storage materials. Energy Environ Sci 2012;5:9698e725; (b)Hu¨gle T, Hartl M, Lentz D. The route to a feasible hydrogen-storage material: MOFs versus ammonia borane. Chem Eur J 2011;17:10184e207; (c)Marder TB. Will we soon be fueling our automobiles with ammoniaeborane? Angew Chem Int Ed Engl 2007;46:8116e8. [8] (a)Xiong ZT, Yong CK, Wu GT, Chen P, Shaw W, Karkamkar A, et al. High-capacity hydrogen storage in lithium and sodium amidoboranes. Nat Mater 2008;7:138e41; (b)Xia GL, Li L, Guo ZP, Gu QF, Guo YH, Yu XB, et al. Stabilization of NaZn(BH4)3 via nanoconfinement in SBA-15
4952
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 4 9 4 7 e4 9 5 3
towards enhanced hydrogen release. J Mater Chem A 2013;1:250e7; (c)Diyabalanage HVK, Shrestha RP, Semelsberger TA, Scott BL. Calcium amidotrihydroborate: a hydrogen storage material. Angew Chem Int Ed Engl 2007;6:8995e7; (d)Blaquiere N, Diallo-Garcia S, Gorelsky SI, Black DA, Fagnou K. Ruthenium-catalyzed dehydrogenation of ammonia boranes. J Am Chem Soc 2008;130:14034e5; (e)Wright WRH, Berkeley ER, Alden LR, TomBaker R, Sneddon LG. Dehydrogenation of ammonia-borane by Shvo’s catalyst. Chem Commun 2011;47:3177e9. [9] (a)Cao N, Luo W, Cheng GZ. One-step synthesis of graphene supported Ru nanoparticles as efficient catalysts for hydrolytic dehydrogenation of ammonia borane. Int J Hydrogen Energy 2013;38:11964e72; (b)Yang L, Su J, Meng XY, Luo W, Cheng GZ. In situ synthesis of graphene supported Ag@CoNi coreeshell nanoparticles as highly efficient catalysts for hydrogen generation from hydrolysis of ammonia borane and methylamine borane. J Mater Chem A 2013;1:10016e23; (c)Du YS, Cao N, Yang L, Luo W, Cheng GZ. One-step synthesis of magnetically recyclable RGO supported Cu@Co core-shell nanoparticles: highly efficient catalysts for hydrolytic dehydrogenation of ammonia borane and methylamine borane. New J Chem 2013;37:3035e42; (d)Yang L, Luo W, Cheng GZ. Graphene-supported Ag-based coreeshell nanoparticles for hydrogen generation in hydrolysis of ammonia borane and methylamine borane. ACS Appl Mater Interfaces 2013;5:8231e40; (e)Sanyal U, Demirci UB, Jagirdar BR, Miele P. Hydrolysis of ammonia borane as a hydrogen source: fundamental issues and potential solutions towards implementation. ChemSusChem 2011;4:1731e9; (f)Singh AK, Xu Q. Synergistic catalysis over bimetallic alloy nanoparticles. ChemCatChem 2013;5:652e76; (g)Zhu QL, Li J, Xu Q. Immobilizing metal nanoparticles to metaleorganic frameworks with size and location control for optimizing catalytic performance. J Am Chem Soc 2013;135:10210e3; (h)Wang ZL, Yan JM, Wang HL, Jiang Q. Self-protective cobalt nanocatalyst for long-time recycle application on hydrogen generation by its free metal-ion conversion. J Power Sources 2013;243:431e5; (i)Yan JM, Wang ZL, Wang HL, Jiang Q. Rapid and energyefficient synthesis of a grapheneeCuCo hybrid as a high performance catalyst. J Mater Chem 2012;22:10990e3; (j)Wang HL, Yan JM, Wang LZ, Jiang Q. One-step synthesis of Cu@FeNi core-shell nanoparticles: highly active catalyst for hydrolytic dehydrogenation of ammonia borane. Int J Hydrogen Energy 2012;37:10229e35. [10] (a)Furukawa H, Cordova KE, O’Keeffe M, Yaghi OM. The chemistry and application of metal-organic frameworks. Science 2013;341:1230444; (b)Paz FAA, Klinowski J, Vilela SMF, Tome´ JPC, Cavaleiroc JAS, Rocha J. Ligand design for functional metaleorganic frameworks. Chem Soc Rev 2012;41:1088e110; (c)Zhao D, Timmons DJ, Yuan DQ, Zhou HC. Tuning the topology and functionality of metal-organic frameworks by ligand design. Acc Chem Res 2011;44:123e33; (d)Yang QY, Liu DH, Zhong CL, Li JR. Development of computational methodologies for metaleorganic frameworks and their application in gas separations. Chem Rev 2013;113:8261e323. [11] (a)Wang C, Liu D, Lin W. Metaleorganic frameworks as a tunable platform for designing functional molecular materials. J Am Chem Soc 2013;135:13222e34; (b)Huxford RC, Rocca JD, Lin W. Metaleorganic frameworks
[12]
[13]
[14]
[15]
[16] [17]
[18] [19]
[20]
as potential drug carriers. Curr Opin Chem Biol 2010;14:262e8. (a)Jhung SH, Khan NA, Hasan Z. Analogous porous metaleorganic frameworks: synthesis, stability and application in adsorption. Cryst Eng Commun 2012;14:7099e109; (b)Gu ZY, Yang CX, Chang N, Yan XP. Metaleorganic framework growth at functional interfaces: thin films and composites for diverse applications. Acc Chem Res 2012;45:734e45; (c)Bradshaw D, Garai A, Huo J. Metal organic frameworks for analytical chemistry: from sample collection to chromatographic separation. Chem Soc Rev 2012;41:2344e81. (a)El-Shall MS, Abdelsayed V, Khder AERS, Hassan HMA, ElKaderi HM, Reich TE. Metallic and bimetallic nanocatalysts incorporated into highly porous coordination polymer MIL101. J Mater Chem 2009;19:7625e31; (b)Li PZ, Aranishi K, Xu Q. ZIF-8 immobilized nickel nanoparticles: highly effective catalysts for hydrogen generation from hydrolysis of ammonia borane. Chem Commun 2012;48:3173e5; (c)Kuo CH, Tang Y, Chou LY, Sneed BT, Brodsky CN, Zhao ZP, et al. Yolkeshell nanocrystal@ZIF-8 nanostructures for gasphase heterogeneous catalysis with selectivity control. J Am Chem Soc 2012;134:14345e8; ¨ rfer J, Friedrich M, Miyajima N, (d)HermannsdO ¨ mmel SK, Kempe R. Ni/Pd@MIL-101: Albuquerque R, U synergistic catalysis with cavity-conform Ni/Pd nanoparticles. Angew Chem Int Ed Engl 2012;51:11473e4; (e)Gu Xj, Lu ZH, Jiang HL, Akita T, Xu Q. Synergistic catalysis of metal organic framework-immobilized AuPd nanoparticles in dehydrogenation of formic acid for chemical hydrogen storage. J Am Chem Soc 2011;133:11822e5; (f)Jiang HL, Akita T, Ishida T, Haruta M, Xu Q. Synergistic catalysis of Au@Ag core-shell nanoparticles stabilized on metal-organic framework. J Am Chem Soc 2011;133:1304e6; (g)Moon HR, Lim DW, Suh MP. Fabrication of metal nanoparticles in metaleorganic frameworks. Chem Soc Rev 2013;42:1807e24. Aijaz A, Karkamkar A, Choi YJ, Tsumori Nobuko, Ronnebro, et al. Immobilizing highly catalytically active Pt nanoparticles inside the pores of metal-organic framework: a double solvents approach. J Am Chem Soc 2012;134:13926e9. Fe´rey G, Mellot-Draznieks C, Serre C, Millange F, Dutour J, Surble´ S, et al. A chromium terephthalate-based solid with unusually large pore volumes and surface area. Science 2005;309:2040e2. Hermannsdo¨rfer J, Kempe R. Selective palladium-loaded MIL-101 catalysts. Chem Eur J 2011;17:8071e7. The BET surface area of the as-synthesized MIL-101 is lower than the reported value by Fe´rey et al. (ref. [15]), but is close to the value reported by others (ref. [16]). See supporting information. (a)Chen GZ, Wu SJ, Liu HL, Jiang HF, Li YW. Palladium supported on an acidic metaleorganic framework as an efficient catalyst in selective aerobic oxidation of alcohols. Green Chem 2013;15:230e5; (b)Huang YB, Liu SJ, Lin ZJ, Li WJ, Li XF, Cao R. Facile synthesis of palladium nanoparticles encapsulated in amine-functionalized mesoporous metaleorganic frameworks and catalytic for dehalogenation of aryl chlorides. J Catal 2012;292:111e7. ¨ , Sun S. Catalytic hydrolysis of Sun D, Mazumder V, Metin O ammonia borane via cobalt palladium nanoparticles. ACS Nano 2011;5:6458e64.
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 4 9 4 7 e4 9 5 3
¨ nder M. Hydrolytic dehydrogenation of [21] Kılıc¸ B, S‚encanlı S, O ammonia borane catalyzed by reduced graphene oxide supported monodisperse palladium nanoparticles: high activity and detailed reaction kinetics. J Mol Catal A Chem 2012;361:104e10. ¨ zkar S. Zeolite confined palladium(0) [22] Rakap M, O nanoclusters as effective and reusable catalyst for hydrogen generation from the hydrolysis of ammonia-borane. Int J Hydrogen Energy 2010;35:1305e12. ¨ , S‚ahin S, O ¨ zkar S. Water-soluble poly(4[23] Metin O styrenesulfonic acid-co-maleic acid) stabilized ruthenium(0) and palladium(0) nanoclusters as highly active catalysts in hydrogen generation from the hydrolysis of ammoniaborane. Int J Hydrogen Energy 2009;34:6304e13. [24] Chandra M, Xu Q. Room temperature hydrogen generation from aqueous ammonia-borane using noble metal nanoclusters as highly active catalysts. J Power Sources 2007;168:135e42. [25] Xu Q, Chandra M. A portable hydrogen generation system: catalytic hydrolysis of ammonia-borane. J Alloy Compd 2007;446e447:729e32.
4953
[26] Xi PX, Chen FJ, Xie GQ, Ma C, Liu HY, Shao CW, et al. Surfactant free RGO/Pd nanocomposites as highly active heterogeneous catalysts for the hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage. Nanoscale 2012;4:5597e601. [27] Wang J, Qin YL, Liu X, Zhang XB. In situ synthesis of magnetically recyclable graphene-supported Pd@Co coreeshell nanoparticles as efficient catalysts for hydrolytic dehydrogenation of ammonia borane. J Mater Chem 2012;22:12468e70. ¨ , Kayhan E, O ¨ zkar S, Schneider JJ. Palladium [28] Metin O nanoparticles supported on chemically derived graphene: an efficient and reusable catalyst for the dehydrogenation of ammonia borane. Int J Hydrogen Energy 2012;37:8161e9. ¨ zkar S. Polymer-immobilized palladium [29] Rakap M, Kalu EE, O supported on TiO2 (Pd-PVB-TiO2) as highly active and reusable catalyst for hydrogen generation from the hydrolysis of unstirred ammoniaeborane solution. Int J Hydrogen Energy 2011;3:1448e55.
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ScienceDirect journal homepage: www.elsevier.com/locate/he
Short Communication
Pd nanoparticles supported on MIL-101 as highperformance catalysts for catalytic hydrolysis of ammonia borane Hongmei Dai a, Jun Su c, Kai Hu a, Wei Luo a,b,*, Gongzhen Cheng a a
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, PR China Suzhou Institute of Wuhan University, Suzhou, Jiangsu 215123, PR China c Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China b
article info
abstract
Article history:
Well dispersed ultrafine Pd NPs have been immobilized in the framework of MIL-101, and
Received 17 December 2013
tested for the catalytic hydrolysis of ammonia borane. The powder XRD, N2 adsorptione
Received in revised form
desorption, TEM, and ICP-AES were employed to characterize the Pd@MIL-101 catalyst. The
11 January 2014
as-synthesized Pd@MIL-101 exhibit the highest catalytic activity toward hydrolysis of AB
Accepted 12 January 2014
among the Pd-based nano-catalysts ever reported, with the TOF value of 45 mol H2 min1
Available online 12 February 2014
(mol Pd)1. Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
Keywords:
reserved.
MIL-101 Palladium Ammonia borane Hydrogen storage
1.
Introduction
One of the challenges of 21st century is to develop and sustain a carbon-neutral economy in place of the current prevalent petroleum economy. Hydrogen, producing only water as a byproduct, has been considered to be the most promising solution for alternative energy applications [1]. However, one of the most application obstacles is the safe and efficient storage of hydrogen [2]. Various hydrogen storage approaches
are currently being investigated, including metal hydrides [3], sorbent materials [4], and chemical hydride systems [5]. Boron, nitrogen containing compounds have attracted much attention because of their high gravimetric hydrogen densities and favorable kinetics of hydrogen release [6]. Ammonia borane (NH3eBH3, AB) has recently received a great interest, because of its 19.6 wt% hydrogen content, high stability, and environmental benignity [7]. The hydrogen stored in AB can be released through different ways [8], but the hydrolysis of AB using transition metal catalysts at ambient conditions seems
* Corresponding author. College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, PR China. Tel.: þ86 2787467716. E-mail address: [email protected] (W. Luo). 0360-3199/$ e see front matter Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2014.01.068
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to be the most convenient route for the portable applications [9]. So far, many catalyst systems have been tested for hydrogen generation from the hydrolysis of AB, however, the optimal compromise between costs, efficiency and recyclability are still remains considerable challenges. On the other hand, due to the high specific surface area and tunable pore size, metal-organic frameworks (MOFs) have attracted growing attention in the application of gas sorption and storage [10], drug delivery [11], and molecular separation [12]. Given the similarity to zeolites, loading of metal nanoparticles (NPs) inside the porous materials of MOFs could afford solid catalysts. The porous structures of MOFs could restrain the aggregation of the metal NPs, and further affect the catalytic activity and recyclability of the catalysts. Loading of metal NPs into the porous of MOFs is of current interest [13]. So far, to the best of our knowledge, there have been only about two examples concerning Pt@MIL-101 [14], and Ni@ZIF8 [13b] for catalytic hydrolysis of ammonia borane. Herein, we reported the generation of highly dispersed Pd NPs immobilized in MIL-101. MIL-101 with two cavities of ca. 2.9 and 3.4 nm free diameters accessible through two pore windows of ca. 1.2 and 1.6 nm, was chosen because of its extra high specific surface area, high thermal stability (up to 300 C), and high chemical stability to water [15]. The catalytic hydrolysis of ammonia borane of the as-synthesized Pd@MIL101 was studied. Compared with other reported Pd-based catalysts, the Pd@MIL-101 exhibits the highest catalytic activity toward hydrolysis of ammonia borane at ambient temperature.
2.
Experimental
2.1.
Chemicals and materials
All chemicals were commercial and used without further purification. Chromic nitrate nonahydrate (Cr(NO3)3$9H2O, Sinopharm Chemical Reagent Co., Ltd., 99%), aqueous hydrofluoric acid (HF, Sinopharm Chemical Reagent Co., Ltd., 40%), ammonium fluoride (NH4F, Sinopharm Chemical Reagent Co., Ltd., 96%), hydrochloric acid (HCl, Sinopharm Chemical Reagent Co., Ltd., 37%), palladium chloride (PdCl2, Wuhan Greatwall Chemical Co., Ltd., 99%), terephthalic acid (HO2CC6H4CO2H, Sinopharm Chemical Reagent Co., Ltd., 99%), sodium borohydride (NaBH4, Sinopharm Chemical Reagent Co., Ltd, 96%),ammonia borane(NH3BH3, Aldrich, 97%), ethanol (C2H5OH, Sinopharm Chemical Reagent Co., Ltd., >99.8%) were used as received. We use ordinary distilled water as the reaction solvent.
2.2.
Synthesis of MIL-101
MIL-101 was synthesized using the reported procedure [16]. Terephthalic acid (332 mg, 2.0 mmol), Cr(NO3)3$9H2O (800 mg, 2.0 mmol), aqueous HF (0.1 mL, 40 wt%) and de-ionized water (9.6 mL) were placed in a 50 mL Teflon-liner autoclave and heated at 220 C for 8 h. After natural cooling, the resulting green powder of MIL-101 with formula Cr3F(H2O)2O[(O2C) C6H4(CO2)]3$nH2O (n 25) was doubly filtered off using two glass filters with pore sizes of 40 mm to eliminate the
unreacted crystals of terephthalic acid, and then further purified by solvothermal treatment in ethanol at 80 C for 24 h. The resulting green solid was soaked in NH4F (1 M) solution at 70 C for 24 h to eliminate the terephthalic acid inside the pores of MIL-101 and immediately filtered resulting green solid was finally dried overnight at 150 C under vacuum for further use.
2.3.
Synthesis of H2PdCl4
A solution of tetrachloropalladinic acid (0.01 M, H2PdCl4) was prepared by mixing 44.5 mg of PdCl2 into 25 mL of HCl (0.02 M) aqueous solution under stirring at room temperature until complete dissolution.
2.4.
Synthesis of Pd@MIL-101
Activated MIL-101 (100 mg) was mixed with 10 mL de-ionized water containing (0.01, 0.02, 0.03, 0.04) mmol H2PdCl4 for 24 h, kept the reaction at 35 C and pH ¼ 3.0. The solid was centrifuged and washed with de-ionized water and ethanol. The resulting mixture was then reduced with sodium borohydride (NaBH4, 0.0378 g) at 273 K for 3 h to yield Pd@MIL-101.
2.5.
Hydrolytic dehydrogenation of ammonia borane
A mixture of 50 mg Pd@MIL-101 and 5 mL de-ionized water were kept in a two-necked round-bottom flask. One neck was connected to a pressure-equalization funnel to introduce 3 mL aqueous solution of NH3BH3 (30.8 mg, 1 mmol), and the other neck was connected to a gas burette to monitor the volume of the gas evolution. The reaction started when the aqueous solution was added to the palladium catalyst, and the evolution of gas was monitored using the gas burette. The reactions were carried out at 298 K in air.
2.6. In situ generation of the Pd(0) catalyst and hydrolysis of ammonia borane 1.89 mL solution of H2PdCl4 (0.01 M) was kept in a two-necked round-bottom flask. First introduce 3 mL aqueous solution of NaBH4 (37.8 mg, 1 mmol) to reduce Pd2þ to Pd0, after the hydrogen generation reaction was completed, another equivalent of NH3BH3 (30.8 mg, 1 mmol) was added into the reaction flask. The evolution of gas was monitored by the gas burette. The reactions were carried out at 298 K in air.
2.7. 101
Hydrolysis of ammonia borane catalyzed by MIL-
Except for the replacement of 50 mg Pd@MIL-101 by 50 mg activated MIL-101, the experiment procedures were similar to that of Pd@MIL-101.
2.8.
Reusability test
3 mL of solution containing 30.8 mg AB was added to 5 mL of water dissolved 50 mg 4 wt% Pd@MIL-101, the evolution of gas was monitored as described above. After the hydrogen generation reaction was completed, new aqueous AB solution
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Fig. 1 e (a, b) Low-angle and wide-angle Powder X-ray diffraction patterns of samples: (a) MIL-101; (b) activated MIL-101; (c) 0.74 wt% Pd@MIL-101; (d) 1.5 wt% Pd@MIL-101; (e) 4wt% Pd@MIL-101; (f) 4 wt% Pd@MIL-101 after five runs of catalytic hydrolysis of AB.
(30.8 mg, 3 mL) was added into the reaction flask. The evolution of gas was monitored using the gas burette. Such cycle tests of the catalyst for the hydrolysis of AB were carried out four times in air.
2.9.
Characterization
The morphologies and sizes of the samples were observed by using a Tecnai G20 U-Twin transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) at an acceleration voltage of 200 kV. Powder X-ray diffraction (XRD) patterns were measured by a Bruker D8Advance X-ray diffractometer using Cu Ka radiation source (l ¼ 0.154178 nm) with a velocity of 1 min1. X-ray photoelectron spectroscopy (XPS) measurement was performed with a Kratos XSAM 800 spectrophotometer. The surface area measurements were performed with N2 adsorption/desorption isotherms at liquid nitrogen temperature (77 K) after dehydration under vacuum at 150 C for 12 h using Quantachrome NOVA 4200e. The inductively coupled plasmaatomic emission spectroscopy (ICP-AES) was performed on IRIS Intrepid II XSP (Thermo Fisher Scientific, USA).
3.
PXRD (Fig. 1b), in which a peak at 40.1 corresponding to the Pd(111) is found, confirming the existence of Pd in the framework of MIL-101. The N2 adsorptionedesorption isotherms of MIL-101 and Pd@MIL-101 were shown in Fig. 2. The specific areas of MIL-101, 0.74 wt% Pd@MIL-101, and 4 wt% Pd@MIL-101 were 2081, 1724 and 1603 m2/g respectively [17]. The large decrease in the amount of N2 adsorption and the pore volume [18] (Fig. S1, Table S1) of Pd@MIL-101 indicates that Pd NPs were well dispersed to the frameworks of MIL-101. In the X-ray photoelectron spectroscopy (XPS) (Fig. S2), the 3d5/2 and 3d3/2 peaks of Pd0 [19] appear at 335.2 and 340.5 eV, and no obvious peak of Pd2þ is observed. The morphologies of MIL-101 immobilized Pd NPs were further characterized by transmission electron microscopic (TEM) and energy-dispersive X-ray spectroscopy (EDX) measurements. TEM images of 4 wt%, and 1.46 wt% Pd@MIL-101 (Fig. 3a, b, e and f) indicate that the Pd NPs are well dispersed, and encapsulated in the cages of the MIL-101. The EDX spectra (Fig. 3g and h) confirm the presence of Pd. The
Results and discussion
MIL-101 was synthesized according to the literature [16]. The unreacted terephthalic acid in the pores were removed by solvothermally treated with ethanol and aqueous NH4F solution respectively. The supported Pd@MIL-101 catalyst was prepared through solution infiltration of activated MIL-101 with H2PdCl4 at pH ¼ 3.0, followed by treatment with NaBH4. The low-angle powder X-ray diffractions (PXRD) of the assynthesized MIL-101, activated MIL-101, Pd@MIL-101 with different Pd loadings up to 4 wt%, and the 4 wt% Pd@MIL-101 after the five cycle hydrolysis of AB exhibit no loss of crystallinity (Fig. 1a), indicating that the integrity of the MIL-101 framework is maintained well during the catalyst preparation and catalytic process. Furthermore, from the wide-angle
Fig. 2 e N2 sorption isotherms of (a) activated MIL-101; (b) 0.74 wt% Pd@MIL-101; (c) 4 wt% Pd@MIL-101 at 77 K. Filled and open symbols represent adsorption and desorption branches, respectively.
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Fig. 3 e (a, b) TEM images of 4 wt% Pd@MIL-101reduced by sodium borohydride; (c, d) TEM images of 4 wt% Pd@MIL-101 after five runs of catalytic hydrolysis of AB; (e, f) TEM images of 1.46 wt% Pd@MIL-101; (g) EDX of 4 wt% Pd@MIL-101; (h) EDX of 1.46 wt% Pd@MIL-101.
mean diameter of Pd NPs in 4 wt% Pd@MIL-101 was in the range of 1.4e1.8 nm, with a mean diameter of 1.8 0.4 nm (Fig. S3), which are small enough to be immobilized into the mesoporous cavities of MIL-101. These results indicate that the ultrafine Pd NPs have been effectively immobilized by MIL101, which result in the high catalytic activity and durability for hydrolysis of AB (vide infra). The catalytic activity of Pd@MIL-101 toward hydrolysis of AB were studied. Fig. 4 shows the H2 generation from aqueous AB at ambient conditions in the present of Pd@MIL-101. Among the catalysts of Pd@MIL-101 with different Pd loadings (4.0 wt%, 2.7 wt%, 1.5 wt%, 0.7 wt%, determined by ICPAES, Table S2), the 4 wt% Pd@MIL-101 has the highest activity, with the TOF value of 45 mol H2 min1 (mol Pd)1. Furthermore, as the control experiment, the same amount of Pd NPs reduced by NaBH4 without MIL-101, and MIL-101
without Pd loading were synthesized and applied to hydrolysis of AB, as shown in Fig. S4, only 2.5 equiv. H2 were released for more than 40 min for Pd NPs, and almost no reactivity for MIL-101 toward hydrolysis of AB at room temperature. Moreover, it can be seen from Table 1, the 4 wt% Pd@MIL-101 catalysts exhibit the highest TOF value for catalytic hydrolysis of AB among the Pd-based nano-catalysts ever reported, which confirms the cooperative effect between MIL-101 and Pd NPs. The durability of the catalyst is crucial in the practical application. The durability of 4 wt% Pd@MIL-101 catalyst for hydrolysis of AB was tested by adding another equivalents of aqueous AB solution after the hydrogen generation reaction was complete. As shown in Fig. S5, even after the 5th run, the catalyst still maintained the initial catalytic activity, indicating the Pd NPs have been effectively immobilized in the framework of MIL-101. The representative TEM images of 4 wt
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Foundation of Ministry of Education of China (20120141120034), the Natural Science Foundation of Jiangsu Province (BK20130370), the Natural Science Foundation of Hubei Province (2013CFB288) and Large-scale Instrument and Equipment Sharing Foundation of Wuhan University.
Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.ijhydene.2014.01.068.
Fig. 4 e Hydrogen generation from aqueous AB in the presence of Pd@MIL-101 catalysts at room temperature. Pd/ AB (molar ratio) [ 0.0033, 0.007, 0.0125 and 0.0189 at Pd loadings of 0.74, 1.46, 2.67, and 4.0 wt%.
Table 1 e Catalytic activity of palladium nanoparticle with different support. Catalyst
Metal/AB ratio (mol/ mol)
TOF (molH2 molcatalyst1 min1)
Ref.
0.024
35.7
[20]
0.024 0.006 0.02 0.02 0.025 0.05 0.04 0.02 0.005 0.03 0.0189
22.7 26.3 6.25 5 1.39 0.67 6.25 40.89 15.55 19.1 45
[20] [21] [22] [23] [24] [25] [26] [27] [28] [29] This study
Co35Pd65/C annealed 25 wt% Co35Pd65/C 2.1 wt% RGO@Pd Pd/zeolite PSSA-co-MA-Pd 2 wt% Pd/r-Al2O3 Pd black RGO@Pd [email protected] 2.1wt%CDG-Pd PdePVBeTiO2 4wt%Pd@MIL-101
% Pd@MIL-101 catalyst after the fifth run durability test were shown in Fig. 1c and d. There is no noticeable change in the morphology of the catalyst, indicating that the MIL-101 can stabilize Pd NPs for good durability.
4.
Conclusion
In summary, we have developed a facile method for immobilizing ultrafine Pd NPs into the frameworks of MIL-101, which exhibit highly catalytic activity and durability for catalytic hydrolysis of AB at ambient conditions. This is the first example for MOF-supported Pd catalysts for catalytic hydrolysis of AB. This simple synthetic method can be extended to other MOFs supported metal NP systems for more applications.
Acknowledgments This work was financially supported by the National Natural Science Foundation of China (21201134), the Ph.D Programs
references
[1] (a)Leitao EM, Jurca T, Manners I. Catalysis in service of main group chemistry offer a versatile approach to p-block molecules and materials. Nat Chem 2013;5:817e29; (b)Dalebrook AF, Gan WJ, Grasemann M, Moret S, Laurenczy G. Hydrogen storage: beyond conventional methods. Chem Commun 2013;49:8735e51; (c)Yang J, Sudik A, Wolvertonb C, Siegel DJ. High capacity hydrogen storage materials: attributes for automotive applications and techniques for materials discovery. Chem Soc Rev 2010;39:656e75; (d)Ma SQ, Zhou HC. Gas storage in porous metaleorganic frameworks for clean energy applications. Chem Commun 2010;46:44e53. [2] (a)Schlapbach L, Zu¨ttel A. Hydrogen-storage materials for mobile applications. Nature 2001;414:354e8; (b)Chen P, Xiong ZT, Luo JZ, Lin JY, Tan KL. Interaction of hydrogen with metal nitrides and imides. Nature 2002;420:302e4; (c)Orimo S, Nakamori Y, Eliseo JR, Zu¨ttel A, Jensen CM. Complex hydrides for hydrogen storage. Chem Rev 2007;107:4111e32. [3] Graetz J. New approaches to hydrogen storage. Chem Soc Rev 2009;38:73e82. [4] Suh MP, Park HJ, Prasad TK, Lim DW. Hydrogen storage in metal organic frameworks. Chem Rev 2012;112:782e835. [5] Staubitz A, Robertson APM, Manners I. Ammonia-borane and related compounds as dihydrogen sources. Chem Rev 2010;110:4079e124. [6] (a)Luo W, Campbell PG, Zakharov LN, Liu SY. A singlecomponent liquid-phase hydrogen storage material. J Am Chem Soc 2011;133:19326e9; (b)Huang Z, Autrey T. Boronenitrogenehydrogen (BNH) compounds: recent developments in hydrogen storage, applications in hydrogenation and catalysis, and new syntheses. Energy Environ Sci 2012;5:9257e68; (c)Hamilton CW, Baker RT, Staubitzc A, Manners I. BeN compounds for chemical hydrogen storage. Chem Soc Rev 2009;38:279e93. [7] (a)Yadav M, Xu Q. Liquid-phase chemical hydrogen storage materials. Energy Environ Sci 2012;5:9698e725; (b)Hu¨gle T, Hartl M, Lentz D. The route to a feasible hydrogen-storage material: MOFs versus ammonia borane. Chem Eur J 2011;17:10184e207; (c)Marder TB. Will we soon be fueling our automobiles with ammoniaeborane? Angew Chem Int Ed Engl 2007;46:8116e8. [8] (a)Xiong ZT, Yong CK, Wu GT, Chen P, Shaw W, Karkamkar A, et al. High-capacity hydrogen storage in lithium and sodium amidoboranes. Nat Mater 2008;7:138e41; (b)Xia GL, Li L, Guo ZP, Gu QF, Guo YH, Yu XB, et al. Stabilization of NaZn(BH4)3 via nanoconfinement in SBA-15
4952
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 4 9 4 7 e4 9 5 3
towards enhanced hydrogen release. J Mater Chem A 2013;1:250e7; (c)Diyabalanage HVK, Shrestha RP, Semelsberger TA, Scott BL. Calcium amidotrihydroborate: a hydrogen storage material. Angew Chem Int Ed Engl 2007;6:8995e7; (d)Blaquiere N, Diallo-Garcia S, Gorelsky SI, Black DA, Fagnou K. Ruthenium-catalyzed dehydrogenation of ammonia boranes. J Am Chem Soc 2008;130:14034e5; (e)Wright WRH, Berkeley ER, Alden LR, TomBaker R, Sneddon LG. Dehydrogenation of ammonia-borane by Shvo’s catalyst. Chem Commun 2011;47:3177e9. [9] (a)Cao N, Luo W, Cheng GZ. One-step synthesis of graphene supported Ru nanoparticles as efficient catalysts for hydrolytic dehydrogenation of ammonia borane. Int J Hydrogen Energy 2013;38:11964e72; (b)Yang L, Su J, Meng XY, Luo W, Cheng GZ. In situ synthesis of graphene supported Ag@CoNi coreeshell nanoparticles as highly efficient catalysts for hydrogen generation from hydrolysis of ammonia borane and methylamine borane. J Mater Chem A 2013;1:10016e23; (c)Du YS, Cao N, Yang L, Luo W, Cheng GZ. One-step synthesis of magnetically recyclable RGO supported Cu@Co core-shell nanoparticles: highly efficient catalysts for hydrolytic dehydrogenation of ammonia borane and methylamine borane. New J Chem 2013;37:3035e42; (d)Yang L, Luo W, Cheng GZ. Graphene-supported Ag-based coreeshell nanoparticles for hydrogen generation in hydrolysis of ammonia borane and methylamine borane. ACS Appl Mater Interfaces 2013;5:8231e40; (e)Sanyal U, Demirci UB, Jagirdar BR, Miele P. Hydrolysis of ammonia borane as a hydrogen source: fundamental issues and potential solutions towards implementation. ChemSusChem 2011;4:1731e9; (f)Singh AK, Xu Q. Synergistic catalysis over bimetallic alloy nanoparticles. ChemCatChem 2013;5:652e76; (g)Zhu QL, Li J, Xu Q. Immobilizing metal nanoparticles to metaleorganic frameworks with size and location control for optimizing catalytic performance. J Am Chem Soc 2013;135:10210e3; (h)Wang ZL, Yan JM, Wang HL, Jiang Q. Self-protective cobalt nanocatalyst for long-time recycle application on hydrogen generation by its free metal-ion conversion. J Power Sources 2013;243:431e5; (i)Yan JM, Wang ZL, Wang HL, Jiang Q. Rapid and energyefficient synthesis of a grapheneeCuCo hybrid as a high performance catalyst. J Mater Chem 2012;22:10990e3; (j)Wang HL, Yan JM, Wang LZ, Jiang Q. One-step synthesis of Cu@FeNi core-shell nanoparticles: highly active catalyst for hydrolytic dehydrogenation of ammonia borane. Int J Hydrogen Energy 2012;37:10229e35. [10] (a)Furukawa H, Cordova KE, O’Keeffe M, Yaghi OM. The chemistry and application of metal-organic frameworks. Science 2013;341:1230444; (b)Paz FAA, Klinowski J, Vilela SMF, Tome´ JPC, Cavaleiroc JAS, Rocha J. Ligand design for functional metaleorganic frameworks. Chem Soc Rev 2012;41:1088e110; (c)Zhao D, Timmons DJ, Yuan DQ, Zhou HC. Tuning the topology and functionality of metal-organic frameworks by ligand design. Acc Chem Res 2011;44:123e33; (d)Yang QY, Liu DH, Zhong CL, Li JR. Development of computational methodologies for metaleorganic frameworks and their application in gas separations. Chem Rev 2013;113:8261e323. [11] (a)Wang C, Liu D, Lin W. Metaleorganic frameworks as a tunable platform for designing functional molecular materials. J Am Chem Soc 2013;135:13222e34; (b)Huxford RC, Rocca JD, Lin W. Metaleorganic frameworks
[12]
[13]
[14]
[15]
[16] [17]
[18] [19]
[20]
as potential drug carriers. Curr Opin Chem Biol 2010;14:262e8. (a)Jhung SH, Khan NA, Hasan Z. Analogous porous metaleorganic frameworks: synthesis, stability and application in adsorption. Cryst Eng Commun 2012;14:7099e109; (b)Gu ZY, Yang CX, Chang N, Yan XP. Metaleorganic framework growth at functional interfaces: thin films and composites for diverse applications. Acc Chem Res 2012;45:734e45; (c)Bradshaw D, Garai A, Huo J. Metal organic frameworks for analytical chemistry: from sample collection to chromatographic separation. Chem Soc Rev 2012;41:2344e81. (a)El-Shall MS, Abdelsayed V, Khder AERS, Hassan HMA, ElKaderi HM, Reich TE. Metallic and bimetallic nanocatalysts incorporated into highly porous coordination polymer MIL101. J Mater Chem 2009;19:7625e31; (b)Li PZ, Aranishi K, Xu Q. ZIF-8 immobilized nickel nanoparticles: highly effective catalysts for hydrogen generation from hydrolysis of ammonia borane. Chem Commun 2012;48:3173e5; (c)Kuo CH, Tang Y, Chou LY, Sneed BT, Brodsky CN, Zhao ZP, et al. Yolkeshell nanocrystal@ZIF-8 nanostructures for gasphase heterogeneous catalysis with selectivity control. J Am Chem Soc 2012;134:14345e8; ¨ rfer J, Friedrich M, Miyajima N, (d)HermannsdO ¨ mmel SK, Kempe R. Ni/Pd@MIL-101: Albuquerque R, U synergistic catalysis with cavity-conform Ni/Pd nanoparticles. Angew Chem Int Ed Engl 2012;51:11473e4; (e)Gu Xj, Lu ZH, Jiang HL, Akita T, Xu Q. Synergistic catalysis of metal organic framework-immobilized AuPd nanoparticles in dehydrogenation of formic acid for chemical hydrogen storage. J Am Chem Soc 2011;133:11822e5; (f)Jiang HL, Akita T, Ishida T, Haruta M, Xu Q. Synergistic catalysis of Au@Ag core-shell nanoparticles stabilized on metal-organic framework. J Am Chem Soc 2011;133:1304e6; (g)Moon HR, Lim DW, Suh MP. Fabrication of metal nanoparticles in metaleorganic frameworks. Chem Soc Rev 2013;42:1807e24. Aijaz A, Karkamkar A, Choi YJ, Tsumori Nobuko, Ronnebro, et al. Immobilizing highly catalytically active Pt nanoparticles inside the pores of metal-organic framework: a double solvents approach. J Am Chem Soc 2012;134:13926e9. Fe´rey G, Mellot-Draznieks C, Serre C, Millange F, Dutour J, Surble´ S, et al. A chromium terephthalate-based solid with unusually large pore volumes and surface area. Science 2005;309:2040e2. Hermannsdo¨rfer J, Kempe R. Selective palladium-loaded MIL-101 catalysts. Chem Eur J 2011;17:8071e7. The BET surface area of the as-synthesized MIL-101 is lower than the reported value by Fe´rey et al. (ref. [15]), but is close to the value reported by others (ref. [16]). See supporting information. (a)Chen GZ, Wu SJ, Liu HL, Jiang HF, Li YW. Palladium supported on an acidic metaleorganic framework as an efficient catalyst in selective aerobic oxidation of alcohols. Green Chem 2013;15:230e5; (b)Huang YB, Liu SJ, Lin ZJ, Li WJ, Li XF, Cao R. Facile synthesis of palladium nanoparticles encapsulated in amine-functionalized mesoporous metaleorganic frameworks and catalytic for dehalogenation of aryl chlorides. J Catal 2012;292:111e7. ¨ , Sun S. Catalytic hydrolysis of Sun D, Mazumder V, Metin O ammonia borane via cobalt palladium nanoparticles. ACS Nano 2011;5:6458e64.
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 4 9 4 7 e4 9 5 3
¨ nder M. Hydrolytic dehydrogenation of [21] Kılıc¸ B, S‚encanlı S, O ammonia borane catalyzed by reduced graphene oxide supported monodisperse palladium nanoparticles: high activity and detailed reaction kinetics. J Mol Catal A Chem 2012;361:104e10. ¨ zkar S. Zeolite confined palladium(0) [22] Rakap M, O nanoclusters as effective and reusable catalyst for hydrogen generation from the hydrolysis of ammonia-borane. Int J Hydrogen Energy 2010;35:1305e12. ¨ , S‚ahin S, O ¨ zkar S. Water-soluble poly(4[23] Metin O styrenesulfonic acid-co-maleic acid) stabilized ruthenium(0) and palladium(0) nanoclusters as highly active catalysts in hydrogen generation from the hydrolysis of ammoniaborane. Int J Hydrogen Energy 2009;34:6304e13. [24] Chandra M, Xu Q. Room temperature hydrogen generation from aqueous ammonia-borane using noble metal nanoclusters as highly active catalysts. J Power Sources 2007;168:135e42. [25] Xu Q, Chandra M. A portable hydrogen generation system: catalytic hydrolysis of ammonia-borane. J Alloy Compd 2007;446e447:729e32.
4953
[26] Xi PX, Chen FJ, Xie GQ, Ma C, Liu HY, Shao CW, et al. Surfactant free RGO/Pd nanocomposites as highly active heterogeneous catalysts for the hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage. Nanoscale 2012;4:5597e601. [27] Wang J, Qin YL, Liu X, Zhang XB. In situ synthesis of magnetically recyclable graphene-supported Pd@Co coreeshell nanoparticles as efficient catalysts for hydrolytic dehydrogenation of ammonia borane. J Mater Chem 2012;22:12468e70. ¨ , Kayhan E, O ¨ zkar S, Schneider JJ. Palladium [28] Metin O nanoparticles supported on chemically derived graphene: an efficient and reusable catalyst for the dehydrogenation of ammonia borane. Int J Hydrogen Energy 2012;37:8161e9. ¨ zkar S. Polymer-immobilized palladium [29] Rakap M, Kalu EE, O supported on TiO2 (Pd-PVB-TiO2) as highly active and reusable catalyst for hydrogen generation from the hydrolysis of unstirred ammoniaeborane solution. Int J Hydrogen Energy 2011;3:1448e55.