Multi-walled carbon nanotubes reinforced interpenetrating polymer network with ultrafast self-healing and anti-icing attributes

DOI: 10.1002/slct.201902614

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z Inorganic Chemistry

Lanthanide (III) Metal-Organic Frameworks: Syntheses, Structures and Supercapacitor Application Shankhamala Ghosh, Amrita De Adhikari, Jyotishka Nath, Ganesh C. Nayak,* and Hari Pada Nayek*[a] Three new lanthanide-MOFs, [(TATMB)2Ce2⋅3DMSO-H2O]⋅7H2O (MOF Ce), [(TATMB)2Pr2⋅4DMSO]⋅7H2O⋅DMF (MOF Pr) and [(TATMB)2Nd2⋅3DMSO⋅H2O]⋅6H2O (MOF Nd) were synthesized by the reaction of hydrated lanthanide salts and 3,3’,3’’-((1,3,5triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid (H3TATMB) under solvothermal reaction condition. All MOFs were characterized by standard instrumentation techniques, for example, FT-IR spectroscopy, elemental analysis, etc. The solid-state structures were determined by single-crystal X-ray diffraction analyses. It revealed that all MOFs formed two-dimensional frameworks by the coordination assisted pathway of ligand molecules and lanthanide(III) ions. All MOFs were investigated as supercapacitor electrode material by using the conventional

three-electrode method by using TEABF4 in acetonitrile as electrolyte. It was observed that MOF Ce exhibited a maximum specific capacitance of 572 Fg 1 at a current density of 1 A g 1 among all three MOFs. The specific capacitance retention of the material was found to be 81% after successful completion of 5000 charging-discharging cycles. To the best of our knowledge, the specific capacitance of MOF Ce is highest reported for lanthanide MOFs without any redox-active additive until now. Moreover, for the first time, MOF Ce has been used to fabricate a device, which exhibited significant responses for various LED lights and showed a maximum specific capacitance of 88 Fg 1 at a current density of 2 A g 1.

Introduction

materials to develop supercapacitors. Recently, metal-organic frameworks (MOFs) has become an area of much interest in making supercapacitors electrode materials. MOFs have already got profound applications in the fields of gas adsorption and storage,[8] sensing of small molecules[9] and metal ions,[10] drug delivery,[11] chemical separation,[12] catalysis.[13] Their highly crystalline[14] and systematic framework arrangement, structural diversity,[15] outstanding porosity[16] and surface area accounts for their high functionality and potential applications. MOFs can act as excellent precursors for synthesizing highly porous metal oxides simply by annealing them at high temperature[17] in a furnace. These metal oxides preserve all the important properties of the MOF such as porosity and high surface area. Formation of metal oxide further increases the surface area which can lead to greater accumulation of charge, thus making it a potential candidate for the supercapacitor electrode material. Alternatively, MOFs are directly used[18] as the electroactive material in supercapacitors just by pre-treatment with some conducting copolymers like Acyplex, Nafion, Flemion, etc. Due to their highly pure crystalline nature, porosity and outstanding surface area, MOFs are also occasionally embedded in porous carbon,[19] GO[20] and CNTs[21] to increase their conducting ability. For instance, MOFs containing transition metals such as cobalt, nickel, copper have been proven as electrode materials for supercapacitor application. The specific capacitance of these MOFs ranges from 206.76 Fg 1 to 2564 Fg 1. The highest specific capacitance value of 2564 Fg 1 was obtained for a layered Co–MOF and reported by Wei and co-workers.[22] However, lanthanide MOFs have scarcely been investigated as supercapacitor electrode materials as compared to transition metal-containing MOFs. A few Ce(III) MOFs have

Ever-increasing shortage of non-renewable energy sources and gradual worsening of environmental pollution has become a significant barrier that humanity is facing today. Development and implementation of sustainable energy storage devices is a major research target to balance the worldwide environmental energy crisis.[1] Energy storage devices, for instance, batteries and capacitors, are revolutionary discoveries for energy storage and they are in much use these days due to their prospective application in both storage and release of energy.[2] However, there are some crucial differences between their impacts due to their distinguishable functionality.[3] Batteries are rich in energy density whereas capacitors possess superior power density. In addition, capacitors can safely charge and discharge at a much higher rate than batteries and survive a larger no of charging-discharging cycles.[4] On this note, combining all the beneficial properties, electrochemical capacitors or supercapacitors are the fascinating energy storage devices of this generation. This is a very important class of energy storage devices owing to their supernormal power density,[5] great reversibility and long cycle life[6] and good intrinsic safety.[7] A variety of metal oxides have been used as pseudocapacitive

[a] S. Ghosh, Dr. A. D. Adhikari, J. Nath, Dr. G. C. Nayak, Dr. H. P. Nayek Department of Applied Chemistry, Indian Institute of Technology (Indian school of Mines), Dhanbad-826004, Jharkhand, India E-mail: [email protected] [email protected] Supporting information for this article is available on the WWW under https://doi.org/10.1002/slct.201902614

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Full Papers been used as supercapacitor electrodes by incorporating them in GO and CNTs or synthesizing CeO2 by annealing the MOF at high temperature. A MOF-derived CeO2 exhibited a remarkably high specific capacitance of 1204 Fg 1 and excellent stability even after 5000 charge-discharge cycles with a negligible change in retention of capacity.[23] Recently, Wei et al. synthesized dumbbell shaped CeO2 from a Ce-BTC MOF[24] and used as an electrode in the presence of KOH and K4[Fe(CN)6] as the electrolyte. The capacitor showed significant specific capacitance of 779 and 501 Fg 1 at rates of 1 and 15 Ag 1 respectively. Wang group reported several cerium (III) metalorganic framework derived composites (Ce–MOF/CNT and Ce– MOF/GO) and investigated their electrochemical behavior. Interestingly, direct use of lanthanide MOFs as supercapacitor material is rare and one could find only a single example of Ce–MOF in the literature.[25] Inspired by these previous investigations and as a part of our recent project, some new materials are being developed for supercapacitor application. The present study reports the synthesis, characterization, and application of three new lanthanide MOFs (MOF Ce, MOF Pr, and MOF Nd). All MOFs were characterized by standard analytical techniques such as FT-IR spectroscopy, elemental analysis, etc. The thermal stability of all MOFs was investigated by TG analysis. The solid-state structures were determined by single-crystal X-ray diffraction analyses. The phase purity was studied by powder X-ray diffraction analysis. The MOFs were studied as a supercapacitor electrode material. They were found to be electroactive and showed significant specific capacitance values without any modification to their original state and structure. A device based on MOF Ce was fabricated and its performance for various LED lights was also noted.

ature, single crystals of each MOF were obtained. The MOFs were found to be stable in an open atmosphere. The formation of MOFs was supported by several characterization techniques such as FT-IR spectroscopy, elemental analyses. The solid-state structures of all MOFs were determined by single-crystal X-ray diffraction analysis. The thermal stability was determined by TG analyses. Powder X-ray diffraction (PXRD) patterns of assynthesized MOFs are almost matched pretty well (figure S1-S3, supporting information) with the simulated patterns which were obtained from the single-crystal X-ray diffraction analyses. This confirms the phase purity of the bulk crystalline materials. FT-IR spectroscopy In the FT-IR spectrum of H3TATMB, a strong band at 1695 cm 1 because of [ν(C=O)] stretching of the carboxylic acid moiety is observed.[27] This band is disappeared for MOFs, thus confirming deprotonation of carboxylic acid moieties in all MOFs (figure S4-S6, supporting information). This is further supported by the appearance of two bands around 1620 cm 1 and 1412 cm 1 in all compounds. These bands are attributed to asymmetric and symmetric stretching of carboxylate group [ν(COO)] respectively.[28] The difference between asymmetric and symmetric stretching vibration of a carboxylate group, ~ [ν(COO)] is approximately 200 cm 1, which is typical for any carboxylate bonded to metal ions in a bidentate fashion.[29] A sharp band approximately at 1012 cm 1 which accounts for [ν(S=O)] stretching, evidences the existence of coordinated or free DMSO molecules in all structures.[30] Additionally, a broad band around 3435 cm 1 appears for all structures due to the overlap of [ν(O H)] and [ν(N H)] stretching vibrations. Description of Structures

Results and Discussion Synthesis The ligand, 3,3’,3’’-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))-tribenzoic acid (H3TATMB) was synthesized by the reaction of 3aminobenzoic acid with cyanuric chloride in the presence of NaHCO3 and NaOH in a mixture of water and 1,4-Dioxane.[26] Three new two-dimensional MOFs were synthesized in a solvothermal reaction of H3TATMB with Ce(NO3)3⋅6H2O (MOF Ce) or Pr(NO3)3⋅6H2O (MOF Pr) or Nd(NO3)3⋅6H2O (MOF Nd) respectively (Scheme 1). The reaction mixture was taken in a mixture of DMSO, DMF, and water (2:2:1, v/v) and heated at 90 °C for 48 hours. After cooling to room temper-

Single crystals for each MOF were found to be suitable for single-crystal X-ray diffraction analysis. The study revealed that all MOFs crystallize in the monoclinic space group Cc with four formula units per unit cell (Z = 4). Table 1 contains detailed crystallographic information. All structures exhibit similar twodimensional (2D) frameworks differing in a number of coordinating solvents to lanthanide ions (Ln3 +) or solvent of crystallization. Each asymmetric unit contains two deprotonated ligands, [TATMB]3 and two lanthanide ions. In MOF Ce, each [TATMB]3 is bonded to three crystallographically equivalent Ce(III) ions (Ce1, Ce1’ and Ce1’’) and one independent Ce (III) ion (Ce2) through six oxygen atoms of the ligand (figure 1a). Among two Ce(III) ions, Ce1 is nine-coordinated by eight oxygen atoms (O1-O7 and O9) from five [TATMB]3 ligands and one oxygen atom (O12) from one DMSO molecule. The Ce2 is positioned at the centre of a polyhedron formed by seven oxygen atoms (O5, O7-O11, and O15) from four [TATMB]3 ligands, two oxygen atoms (O13 and O14) from two DMSO molecules and one water molecule (figure 1b). The Ce–O bond lengths lie in the range of 2.478(8)-2.822(7) Å, which are in close agreement with other cerium(III) containing compounds.[31]

Scheme 1. Synthesis of MOFs MOF Ce, MOF Pr and MOF Nd.

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Full Papers Two cerium(III) ions with a non-bonded Ce⋅⋅⋅Ce distance 4.012 Å are further bridged by multiple [TATMB]3 ligands, thus resulting in a two-dimensional framework structure (figure 2).

Table 1. Single crystal data and structure refinement parameters for MOF Ce, MOF Pr, and MOF Nd. Complex

MOF-Ce

MOF-Pr

MOF-Nd

Empirical formula Formula weight Temperature/ K Crystal system Space group a/Å b/Å c/Å α/° β/° γ/° Volume/Å3 Z 1calcg/cm3 μ/mm-1 F(000) Crystal size/ mm3 Radiation

C54H64Ce2N12O22S3

C59H75N13O24Pr2S4

C54H62N12Nd2O22S3

1609.59

1760.38

1615.81

293(2)

293(2)

293(2)

monoclinic

Monoclinic

monoclinic

Cc 14.2539(6) 24.7342(11) 20.9924(10) 90 95.122(2) 90 7371.5(6) 4 1.450 1.379 3248.0 0.22 × 0.18 × 0.15 MoKα (λ = 0.71073) 4.912 to 55.118

Cc 14.1886(3) 24.7819(3) 20.9589(5) 90 92.606(2) 90 7362.0(3) 4 1.588 1.504 3576.0 0.2 × 0.18 × 0.15

Cc 14.145(5) 24.807(6) 21.033(8) 90 92.03(3) 90 7376(4) 4 1.455 12.167 3256.0 0.20 × 0.18 × 0.15 CuKα (λ = 1.5478)

141942

53929

33443

16467 [Rint = 0.0409, Rsigma = 0.0276] 16467/2/826

13111 [Rint = 0.0549, Rsigma = 0.0523] 13111/2/893

9601 [Rint = 0.0698, Rsigma = 0.0987] 9601/2/835

1.087

1.041

0.941

R1 = 0.0526, wR2 = 0.1475

R1 = 0.0877, wR2 = 0.2214

R1 = 0.0661, wR2 = 0.1607

R1 = 0.0564, wR2 = 0.1502

R1 = 0.1022, wR2 = 0.2339

R1 = 0.0864, wR2 = 0.1684

2.33/-2.55

1.70/-1.84

2.42/-1.27

2Θ range for data collection/° Reflections collected Independent reflections Data/restraints/parameters Goodness-offit on F2 Final R indexes [I > = 2σ (I)] Final R indexes [all data] Largest diff. peak/hole / e Å 3

MoKα (λ = 0.71073) 3.286 to 50.99

Figure 2. A two-dimensional framework of MOF Ce viewed along the crystallographic c axis.

7.154 to 140.98

Seven molecules of water are distributed in the solvent accessible free volume of the framework. The MOF Pr has a framework structure with formula unit [(TATMB)2Pr2⋅4DMSO] ⋅7H2O⋅DMF. The Pr(III) ions, Pr1, and Pr2 are deca- or ninecoordinated respectively (figure S7-S8, supporting information). Pr1 is bonded to seven oxygen atoms (O1-O6 and O9) of four [TATMB] ligands and three oxygen atoms (O14-O16) of three coordinated DMSO molecules. A coordination number of nine of Pr2 is satisfied by nine oxygen atoms (O1, O4, and O7-O12) of five [TATMB] ligands and one coordinated DMSO molecule (O13). The Pr–O bond lengths are in the range of 2.465(14)2.780(13) Å, which are consistent with other known compounds of Pr(III).[27] In addition, the Pr⋅⋅⋅Pr non-bonded distance of 3.9742 Å is comparable with reported praseodymium MOFs.[27] The MOF Nd is isostructural with Ce–MOF (figure S9-S10, supporting information). However, six molecules of water are found in the solvent accessible site of the framework of MOF Nd. The Nd–O bond length ranges from 2.398(12)2.705(13) Å which are typical for Nd-MOFs or complexes.[32] Thermogravimetric analysis

Figure 1. (a) Bingling modes of [TATMB]3 ligand with Ce(III) ions in MOF Ce. (b) Coordination environment of Ce(III) ions in MOF Ce.

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Thermogravimetric analyses of all MOFs were performed to access their thermal stabilities up to 700 °C. Figures S11-S13 (supporting information) represent typical TG plots of all compounds. Initial weight loss of 18.74% (calc. 18.65%) for MOF-Ce, up to 206 °C can be attributed to the loss of seven free water molecules which are used as the solvent of crystallization, one coordinated water molecule, and two coordinated DMSO molecules. Second weight loss step, up to 6.22% (calc. 5.97%), at 381 °C is due to the removal of one

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Full Papers remaining DMSO molecule. The remaining framework is stable up to 490 °C, and then slowly decomposes on further increase in temperature. In case of MOF Pr (figure S12 supporting information), initial weight loss of 15.08% (calc. 15.74%), up to 196 °C, can be attributed to the removal of seven free water molecules, one free DMF molecule and one coordinated DMSO molecule. Further weight loss of 9.78% (calc. 10.53%) at 502 °C is due to the removal of two more DMSO molecules. Subsequent weight loss at higher temperature can be due to degradation of the remaining framework. Similar two-step degradation of 12.44% (calc. 12.63%) at 194 °C and 498 °C for MOF Nd (figure S13, supporting information), can be attributed to cumulative removal of six free water molecules, one coordinated water molecule and one DMSO molecule and one coordinated DMSO molecule (second step). The rest of the framework decomposes on further increase in temperature. Figure 3. Cyclic voltammograms of all the MOFs at a scan rate 2 mV/s.

Electrochemical studies The electrochemical studies such as i. e. cyclic voltammetry (CV), galvanostatic charging-discharging (GCD) and electrochemical impedance spectroscopy (EIS) of all MOFs were carried out in Bilogic SP300 instrument by a conventional three-electrode method using the synthesized material as working, AgCl/Ag as reference and platinum as the counter electrode. For electrochemical characterization 1(M) TEABF4 in acetonitrile was used as electrolyte within a potential window of 0.0 to 0.8 V. Cyclic voltammetry was carried out in different scan rates and the frequency was varied from 1 MHz to 1 Hz for electrochemical impedance spectroscopy (EIS) studies. All the measurements were done at room temperature. The detailed explanation of electrode preparation has been provided in the supplementary data file. Cyclic Voltammetry In a typical CV, the potential of an electrode which is immersed in an unstirred solution is fixed and measurement of the resulting current takes place. The CV analyses of all MOFs were performed at different scan rates (2, 3, 5, 10, 20 mVs 1) which are shown in figures S14-S16 (supporting information). The current can be considered as the response signal to the potential excitation signal. From CV plots, it is observed that, with an increase in scan rates, the area of the CV curve increases which can be explained based on the size of the diffusion layer on the electrode-electrolyte interface. At slower scan rate, the diffusion layer is much thicker (compared to faster scan rate) as a result the current, which depends on the flux towards the electrode, decreased as compared to faster scan rate. Figure 3 depicts the CV of all MOFs at a scan rate of 2 mVs 1 and it is observed that in MOF Pr and MOF Nd, no redox peak was obtained in both the positive and negative sweep in the potentiodynamic investigation. However, a pair of distinct peaks are observed in case of MOF Ce which may be due to faradic redox conversion of Ce3 + Ce4 +. The current density of MOF Ce at a scan rate of 2 mVs 1 is higher as compared to that of others (i. e. MOF Pr and MOF Nd) which $

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can be further correlated with the charge-discharge profiles of MOFs. Galvanostatic Charging-Discharging Analysis Specific capacitance, which is the quantification of electroactive materials ability for development of supercapacitor electrode, is a very important parameter for energy storage devices. To access the viability of developed MOFs as electrodes for supercapacitor fabrication, galvanostatic charging-discharging (GCD) analysis was carried out and specific capacitance was calculated for each MOFs with same three-electrode system and electrolyte. All charging-discharging measurements were done within a potential window of 0.0 V to 0.8 V and at five different current densities i. e. from 1 Ag 1 to 5 Ag 1. Figure 4

Figure 4. Galvanostatic charging-discharging plots of MOF Ce, MOF Pr and MOF Nd at a current density 1 A/g

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Full Papers represents the galvanostatic charging-discharging (GCD) profile of all the MOFs at a current density of 1 Ag 1. It can be observed that the MOF Ce has high discharge time compared to the other two MOFs which indicates its higher specific capacitance compared to MOF Pr and MOF Nd. The specific capacitance values of MOFs were calculated by the following equation from GCD discharge time. Specific Capacitance ðCSC Þ ¼

i�t Dv � m

captured at higher scan rates. To justify the practical ability of MOFs, Energy Density (ED) and Power Density (PD) were calculated by using the following equations: Energy Density ðEÞ ¼

Power Density ðPÞ ¼

1 C Dv2 7:2 sc

(ii)

E � 3600 t

(iii)

(i)

where Csc, i, t, Δv, and m corresponds to specific capacitance (Fg 1), constant current (A), discharge time (sec), applied potential range and weight of the electroactive material (g), respectively. At a current density of 1 Ag 1, the MOF Ce shows a specific capacitance of 572 Fg 1, which is higher than MOF Pr and MOF Nd which offer a specific capacitance of 399 Fg 1 and 360 Fg 1, respectively. The specific capacitance was also calculated by varying the current densities of all the MOFs and presented in figure 5.

It is observed that MOF Ce shows the maximum power density 400.00 Wkg 1 along with energy density of 51 Whkg 1. Specific capacitances, energy densities of all MOFs at different current density are given in table 2. A comparative study with

Table 2. Specific capacitance and energy density at different current density of electroactive MOFs MOF

Current Density (A/g)

Specific Capacitance (F/g)

Energy Density (Whkg 1)

Power Density (W/Kg)

MOFCe

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

572 362 296 265 237 399 337 292 263 250 360 315 277 255 243

51 32 26 24 21 36 30 26 23 22 32 28 25 23 22

400 799 1203 1604 2000 400 798 1192 1585 2000 399 800 1202 1607 2000

MOFPr

MOFNd

other reported works has been presented in table S1 (supporting information). Figure 5. Specific capacitance variation at different current densities.

Electrochemical Impedance Spectroscopy (EIS) study

The charging-discharging profiles of all MOFs at different current densities (1-5 A/g) are shown in figures S14-S16 (supporting information). GCD plots for all three MOFs, at different current densities, show a linear nature except for MOF Ce, whose discharge plot for 1 A/g deviates slightly from linearity. This nonlinearity for MOF Ce can be correlated to the redox reaction as mentioned in the CV analysis section. For purely EDLC supercapacitors, triangular charging and discharging curves arises due to fast charging-discharging dynamics. However, a combination of EDLC and Pseudocapacitance mechanism imparts non-linearity to GCD plots due to slow redox reactions. This non-linearity disappears at a higher current density which can be attributed to the fact that the signal contribution of slow redox reaction could not be ChemistrySelect 2019, 4, 10624 – 10631

The response of an electrochemical system with respect to an alternating applied potential can be monitored by EIS study. The frequency dependence impedance can shed light on the underlying chemical processes of the system. The EIS analysis in terms of Nyquist plot is basically a plot of the imaginary component of the impedance against the real component. Real part (Z’) vs. imaginary part (-Z”) explains the frequency response All plots were fitted with equivalent circuits for better understanding the electrochemical process (figure S17, supporting information). The intercept of the real component gives the equivalent series resistance (ESR) which determines the rate of charging and discharging. The electrochemical impedance studies of all MOFs were done between a frequency ranges of 1 Hz to 1 MHz at open circuit potential with an amplitude of 10 mV. From the Nyquist plots, it is seen that it basically consists of two parts, first is a semicircular curve in the higher

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Figure 7. Cyclic stability of the MOFs up to 5000 cycles Figure 6. Nyquist plots of MOF Ce, MOF Pr and MOF Nd.

frequency region and the second is a straight line in the lower frequency region. The impedance spectrum at high-frequency arc corresponds to the charge transfer resistance (Rct) caused by the Faradaic reactions and the double-layer capacitance (Cdl) at the contact interface between electrode and electrolyte and the Rct is directly measured from the semicircular arc diameter. The Rct and Rs values of all the materials are listed in the following table S2 (supporting information). From the Nyquist plot, it is also evident that the slope of the straight line in case of MOF Ce and MOF Nd in low-frequency region is higher than MOF Pr which indicates their superior capacitive behavior and low diffusion ion resistance. Retention and Cyclic stability

Figure 8. (a, b) Assembled cell device; (c) Cell pressed with G-clamp; (d) Charging the cell for 30 secs; (e) Lighting LED after 1 sec of charging; (f) pictorial representation of cell assembly; (g) Lighting 3 mm red LED of 1.8 V after 30 sec of charging; (h) Lighting 3 mm green LED of 2.6 V after 30 sec of charging; (i) Lighting 8 mm red LED of 2.6 V after 1 min of charging.

Long term stability and delivery of charge for the highest possible time is a very important criterion for a good supercapacitor material. A total number of 5000 complete chargingdischarging cycles were performed using the electroactive material and the specific capacitance retention is presented in figure 7. It was found that, after the completion of 5000 cycles, the retention of specific capacitance for MOF Ce was 81%, MOF Pr was 74% and for MOF Nd is about 50%. So, it can also be corroborated from the cyclic stability study that MOF Ce has much higher retention as compared to other MOFs (MOF Pr and MOF Nd) and can be a good candidate for the supercapacitor application.

paper as the separator as in figure 8 (a, b) which was then pressed using G-Clamps (figure 8 c) and 1(M) TEABF4 in acetonitrile was used as the electrolyte to light LEDs of different colors (figure 8 g, h, i). As can be seen in the figure, the device can able to light up 3 mm red and green LED after a charging cycle of 30 seconds. However, it needs to be charged for 1 minute to light up 8 mm red LED.

Device assembly and testing

Electrochemical Analysis of Ce–MOF based device

MOF Ce was found to have better specific capacitance and cyclic stability as compared to MOF Pr and MOF Nd. Therefore, it was employed for device application. The details of the device set-up have been demonstrated in the supporting information and the set-up has been depicted in figure 8. The cathode and the anode were assembled together with tissue

The assembled Ce–MOF based device was further analyzed for its electrochemical performance. Figure S18 (a) and (b) shows the CV and GCD plot of the device at different potential windows (up to 1.8 V), respectively. Similarly, figure S18 (c) and (d) depicts CV and GCD plots of the device at different scan rates and different current densities, respectively at a fixed

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Full Papers potential window of 1.8 V. The peak current increases progressively with an increasing scan rate of CV and the curves are pseudo-symmetric even at the higher scan rate with good current response. From the above plots, it is observed that at 1.8 V potential window device displays the highest area under the CV curve. From figure S18(c), the area of the CV curves increases with an increase in scan rate due to the fast diffusion kinetics. The charge-discharge plot of the device at different potential windows at 2 A/g current density is displayed in figure S18 (b) and from the figure, it is shown that discharge time has been increased with increased potential window. The specific capacitance is found to be 88 Fg 1 at a current density of 2 Ag 1 in this potential window. This specific capacitance value is found to be much lesser than that obtained from the three-electrode setup. This is a common phenomenon associated with the change in measurement condition, electrode fabrication, and cell assembly process. In the device, during electrode preparation, the contact resistance between the current collector and active material, active material coating thickness and uniformity, pore size distribution along with the availability of electrolyte can significantly change the electrochemistry of device which tested in two-electrode configuration as compared to three-electrode setup. Where via threeelectrode setup we can explore the actual electrochemistry of active materials; device electrochemistry can significantly be affected by the processing conditions of electrodes. GCD analysis at 1.8 V at different current density was performed up to 8 A/g current density and shown in figure S18 (d). Table 3 summarized the electrochemical performance of MOF Ce device.

Table 3. Electrochemical analysis of MOF Ce device. MOF

Current Density (A/g)

Specific Capacitance (F/g)

Energy Density (Wh/Kg)

Power Density (W/Kg)

MOFCe

2 4 6 8

88 76 72 56

40 34 32 25

1800 3600 5486 6923

Conclusions Three lanthanide(III) containing MOFs (MOF Ce, MOF Pr, and MOF Nd) were synthesized and characterized by standard analytical techniques. The structural analyses revealed that all MOFs form two-dimensional framework structures. Electrochemical studies showed that all MOF can be used for supercapacitor application. However, MOF Ce exhibited the maximum specific capacitance of 572 Fg 1 at a current density of 1 Ag 1. For MOF Pr and MOF Nd, at the same current density, the specific capacitance values were found to be 399 Fg 1 and 360 Fg 1 respectively. A device based on MOF Ce was assembled and it was able to light up various LED lights.

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Supporting information Experimental section, X-ray powder diffractogram, FT-IR spectra, structures of MOFs, TG plots, CV curves, SEM images all MOFs are provided.

Acknowledgements This work was financially supported by the Science and Engineering Research Board (SERB), India (Order No. SB/EMEQ-013/2014, dated 17/06/2014).

Conflict of Interest The authors declare no conflict of interest. Keywords: Lanthanide-MOF · Electrochemical study Supercapacitor · Cyclic voltammetry · X-ray crystallography

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[1] A. González, E. Goikolea, J. A. Barrena, R. Mysyk, Renewable Sustainable Energy Rev. 2016, 58, 1189–1206. [2] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon, Nat. Mater. 2011, 11, 19. [3] A. Vlad, N. Singh, J. Rolland, S. Melinte, P. M. Ajayan, J. F. Gohy, Sci. Rep. 2014, 4, 4315. [4] F. Zhang, T. Zhang, X. Yang, L. Zhang, K. Leng, Y. Huang, Y. Chen, Energy Environ. Sci. 2013, 6, 1623–1632. [5] Z. Xu, Z. Li, C. M. B. Holt, X. Tan, H. Wang, B. S. Amirkhiz, T. Stephenson, D. Mitlin, J. Phys. Chem. Lett. 2012, 3, 2928–2933. [6] T. Purkait, G. Singh, D. Kumar, M. Singh, R. S. Dey, Sci. Rep. 2018, 8, 640. [7] Y. Huang, W. S. Ip, Y. Y. Lau, J. Sun, J. Zeng, N. S. S. Yeung, W. S. Ng, H. Li, Z. Pei, Q. Xue, Y. Wang, J. Yu, H. Hu, C. Zhi, ACS Nano 2017, 11, 8953– 8961. [8] a) I. Bratsos, C. Tampaxis, I. Spanopoulos, N. Demitri, G. Charalambopoulou, D. Vourloumis, T. A. Steriotis, P. N. Trikalitis, Inorg. Chem. 2018, 57, 7244–7251; b) M. A. Andrés, M. Benzaqui, C. Serre, N. Steunou, I. Gascón, J. Colloid Interface Sci. 2018, 519, 88–96; c) Y. Li, R. T. Yang, Langmuir 2007, 23, 12937–12944; d) Y.-B. Zhang, H. Furukawa, N. Ko, W. Nie, H. J. Park, S. Okajima, K. E. Cordova, H. Deng, J. Kim, O. M. Yaghi, J. Am. Chem. Soc. 2015, 137, 2641–2650; e) F. Gándara, H. Furukawa, S. Lee, O. M. Yaghi, J. Am. Chem. Soc. 2014, 136, 5271–5274. [9] a) H.-R. Tian, C.-Y. Gao, Y. Yang, J. Ai, C. Liu, Z.-G. Xu, Z.-M. Sun, New J. Chem. 2017, 41, 1137–1141; b) S. Khatua, S. Goswami, S. Biswas, K. Tomar, H. S. Jena, S. Konar, Chem. Mater. 2015, 27, 5349–5360; c) K. Tomar, M. Gupta, A. K. Gupta, Inorg. Chem. Commun. 2016, 64, 16–18. [10] a) S. Chand, A. Pal, C. Pal Shyam, C. Das Madhab, Eur. J. Inorg. Chem. 2018, 0; b) Q. Zhang, J. Wang, A. M. Kirillov, W. Dou, C. Xu, C.-L. Xu, L. Yang, R. Fang, W.-S. Liu, ACS Appl. Mater. Interfaces 2018; c) M.-N. Zhang, T.-T. Fan, Q.-S. Wang, H.-L. Han, X. Li, J. Solid State Chem. 2018, 258, 744– 752. [11] M. Almáši, V. Zeleňák, P. Palotai, E. Beňová, A. Zeleňáková, Inorg. Chem. Commun. 2018, 93, 115–120. [12] a) C. Altintas, S. Keskin, RSC Adv. 2017, 7, 52283–52295; b) Y. Chen, H. Wu, D. Lv, R. Shi, Y. Chen, Q. Xia, Z. Li, Ind. Eng. Chem. Res. 2018, 57, 4063–4069. [13] a) A. Karmakar, L. M. D. R. S. Martins, S. Hazra, M. F. C. Guedes da Silva, A. J. L. Pombeiro, Cryst. Growth Des. 2016, 16, 1837–1849; b) A. Karmakar, A. Paul, M. D. M. Rúbio Guilherme, M. F. C. Guedes da Silva, J. L. Pombeiro Armando, Eur. J. Inorg. Chem. 2016, 2016, 5557–5567; c) D. Nainamalai, S. Palaniswamy, Org. Chem. Front. 2018. [14] Y. Watanabe, T. Haraguchi, K. Otsubo, O. Sakata, A. Fujiwara, H. Kitagawa, Chem. Commun. 2017, 53, 10112–10115. [15] R. P. Davies, R. Less, P. D. Lickiss, K. Robertson, A. J. P. White, Cryst. Growth Des. 2010, 10, 4571–4581. [16] a) H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi, A. Ö. Yazaydin, R. Q. Snurr, M. O’Keeffe, J. Kim, O. M. Yaghi, Science 2010, 329,

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Full Papers [17]

[18] [19]

[20]

[21] [22] [23] [24]

424; b) R. Babu, R. Roshan, A. C. Kathalikkattil, D. W. Kim, D.-W. Park, ACS Appl. Mater. Interfaces 2016, 8, 33723–33731. a) F. Meng, Z. Fang, Z. Li, W. Xu, M. Wang, Y. Liu, J. Zhang, W. Wang, D. Zhao, X. Guo, J. Mater. Chem. A 2013, 1, 7235–7241; b) C. Feng, J. Zhang, Y. He, C. Zhong, W. Hu, L. Liu, Y. Deng, ACS Nano 2015, 9, 1730–1739. X. Liu, C. Shi, C. Zhai, M. Cheng, Q. Liu, G. Wang, ACS Appl. Mater. Interfaces 2016, 8, 4585–4591. a) R. R. Salunkhe, Y. Kamachi, N. L. Torad, S. M. Hwang, Z. Sun, S. X. Dou, J. H. Kim, Y. Yamauchi, J. Mater. Chem. A 2014, 2, 19848–19854; b) F. Zheng, G. Xia, Y. Yang, Q. Chen, Nanoscale 2015, 7, 9637–9645. a) J.-P. Meng, Y. Gong, Q. Lin, M.-M. Zhang, P. Zhang, H.-F. Shi, J.-H. Lin, Dalton Trans. 2015, 44, 5407–5416; b) C. Qu, L. Zhang, W. Meng, Z. Liang, B. Zhu, D. Dang, S. Dai, B. Zhao, H. Tabassum, S. Gao, H. Zhang, W. Guo, R. Zhao, X. Huang, M. Liu, R. Zou, J. Mater. Chem. A 2018, 6, 4003–4012. R. Ramachandran, W. Xuan, C. Zhao, X. Leng, D. Sun, D. Luo, F. Wang, RSC Adv. 2018, 8, 3462–3469. J. Yang, Z. Ma, W. Gao, M. Wei, Chem. Eur. J 2017, 23, 631–636. S. Maiti, A. Pramanik, S. Mahanty, Chem. Commun. 2014, 50, 11717– 11720. G. Zeng, Y. Chen, L. Chen, P. Xiong, M. Wei, Electrochim. Acta 2016, 222, 773–780.

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[25] R. Ramachandran, W. Xuan, C. Zhao, X. Leng, D. Sun, D. Luo, F. Wang, RSC Adv. 2018, 8, 3462–3469. [26] C.-Y. Sun, W.-P. To, X.-L. Wang, K.-T. Chan, Z.-M. Su, C.-M. Che, Chem. Sci. 2015, 6, 7105–7111. [27] H. He, S.-H. Chen, D.-Y. Zhang, E.-C. Yang, X.-J. Zhao, RSC Adv. 2017, 7, 38871–38876. [28] S. Pal, A. Bhunia, P. P. Jana, S. Dey, J. Möllmer, C. Janiak, H. P. Nayek, Chem. Eur. J 2015, 21, 2789–2792. [29] a) D. Martínez, M. Motevalli, M. Watkinson, Dalton Trans. 2010, 39, 446– 455; b) G. B. Deacon, R. J. Phillips, Coord. Chem. Rev. 1980, 33, 227–250. [30] R. Vinayak, A. Harinath, C. J. Gómez-García, T. K. Panda, S. Benmansour, H. P. Nayek, ChemistrySelect 2016, 1, 6532–6539. [31] S. Saha, A. Sarkar, S. Das, T. K. Panda, K. Harms, H. P. Nayek, ChemistrySelect 2017, 2, 7865–7872. [32] X.-D. Du, W. Zheng, X.-H. Yi, J.-P. Zhao, P. Wang, C.-C. Wang, CrystEngComm 2018, 20, 2608–2616.

Submitted: July 15, 2019 Accepted: September 3, 2019

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