Catalytic Activity For Hydrogen Generation Research Articles

Highly dispersed RuCo bimetallic nanoparticles supported on carbon black: enhanced catalytic activity for hydrogen generation from NaBH4 methanolysis

A series of carbon black-supported bimetallic Ru–Co nanoparticles catalyst were synthesized via the chemical reduction of corresponding metal precursor in ethylene glycol, for H2 generation from NaBH4 methanolysis. The composition, morphology and structure of the novel nanomaterial were well characterized by XRD, XPS, HRTEM, EDX and SEM, showing the good dispersion of supported Ru–Co nanoparticles with an average diameter of 2.4 nm. Significantly, the highest H2 generation rate is observed in the case of Ru–Co/C catalyst with Ru/Co ratio of 5, achieving 9.36 L min−1 g−1 at 25 °C, which is comparable to the reported pure Ru catalysts. Furthermore, the recycle test confirms our catalyst can be practically applied. Our work highlights the synergetic effect in bimetallic catalytic system for boosting H2 generation rates from NaBH4 methanolysis.

Synthesis, characterization, surface properties and energy device characterstics of 2D borocarbonitrides, (BN) x C1-x , covalently cross-linked with sheets of other 2D materials.

Covalent cross-linking of 2D structures such as graphene, MoS2 and C3N4 using coupling reactions affords the generation of novel materials with new or improved properties. These covalently cross-linked structures provide the counter point to the van der Waals heterostructures, with an entirely different set of features and potential applications. In this article, we describe the materials obtained by bonding borocarbonitride (BCN) layers with BCN layers as well as with other layered structures such as MoS2 and C3N4. While cross-linking BCN layers with other 2D sheets, we have exploited the existence of different surface functional groups on the graphene (COOH) and BN(NH2) domains of the borocarbonitrides as quantitatively determined by FLOSS. Hence, we have thus obtained two different BCN–BCN assemblies differing in the location of the cross-linking and these are designated as GG/BCN–BCN and GBN/BCN–BCN, depending on which domains of the BCN are involved in cross-linking. In this study, we have determined the surface areas and CO2 and H2 adsorption properties of the cross-linked structures of two borocarbonitride compositions, (BN)0.75C0.25 and (BN)0.3C0.7. We have also studied their supercapacitor characteristics and photochemical catalytic activity for hydrogen generation. The study reveals that the covalently cross-linked BCN–BCN and BCN–MoS2 assemblies exhibit increased surface areas and superior supercapacitor performance. The BCN composite with MoS2 also shows high photochemical HER activity besides electrochemical HER activity comparable to Pt. This observation is significant since MoS2 in the nanocomposite is in the 2H form. The present study demonstrates the novelty of this new class of materials generated by cross-linking of 2D sheets of inorganic graphene analogues and their potential applications.

Facile synthesis of a hollow Ni-Fe-B nanochain and its enhanced catalytic activity for hydrogen generation from NaBH4 hydrolysis.

A hollow Ni–Fe–B nanochain is successfully synthesized by a galvanic replacement method using a Fe–B nanocomposite and a NiCl2 solution as the template and additional reagent, respectively. Both the concentration of Ni and the morphology of the resulting Ni–Fe–B alloy are controlled by varying the duration of the replacement process during the synthesis. The Ni–Fe–B sample synthesized for 60 min (Ni–Fe–B-60) shows the best catalytic activity at 313 K, with a hydrogen production rate of 4320 mL min−1 gcat−1 and an activation energy for the NaBH4 hydrolysis reaction of 33.7 kJ mol−1. The good performance of Ni–Fe–B-60 towards the hydrolysis of NaBH4 can be ascribed to both hollow nanochain structural and electronic effects. Furthermore, the effects of temperature, catalyst amount, and concentration of NaOH and NaBH4 on the hydrolysis process are systematically studied, and an overall kinetic rate equation is obtained. The hollow Ni–Fe–B nanochain catalyst also shows good reusability characteristics and maintained its initial activity after 5 consecutive cycles.

Fabrication of Pt–Co NPs supported on nanoporous graphene as high-efficient catalyst for hydrolytic dehydrogenation of ammonia borane

Nanoporous graphene (PG) supported Pt–Co bimetallic nanoparticles were prepared and their catalytic activity in hydrogen generation from hydrolysis of NH3·BH3 solution were examined. The synthesized Pt–Co@PG with a loading amount of 30 wt% Pt–Co (atomic ratio 1:9) exhibited a superior TOF value of 461.17 molH2 min−1 molPt−1 and an activation energy (Ea) value of 32.79 kJ mol−1 for NH3·BH3 hydrolysis. This remarkably enhanced activity was ascribed to the charge interaction between Pt–Co NPs and PG support. The defects and holes on PG acting as the anchoring sites for Pt–Co NPs was beneficial for achieving a uniform distribution and a decreased particle size for the NPs. The Pt–Co@PG catalysts also showed a well-established reusability, with 81.2% of their initial catalytic activity after five runs of reactions, demonstrating that they had high durability.

Highly dispersed Pd-MnOx nanoparticles supported on graphitic carbon nitride for hydrogen generation from formic acid-formate mixtures

Highly dispersed Pd and MnOx nanoparticles supported on the graphitic carbon nitride with different composition have been prepared by a simple liquid deposition-reduction method and used as an efficient FA decomposition catalyst for hydrogen generation. The catalytic activity depends on the Pd-MnOx composition of catalyst, the FA/SF ratio and the reaction temperature. The Pd-MnOx/CN-1 catalyst exhibited excellent catalytic activity for hydrogen generation with the initial TOF of 465 h−1 from formic acid-sodium formate mixture aqueous solution with a FA/SF ratio of 1:8 at 348 K. The synergetic effect between Pd nanoparticles and the carbon nitride support, the Mn/Pd ratios, the good dispersion of nanoparticles and the nature of the carbon nitride support were suggested to be responsible for the efficient catalytic performance of the Pd-MnOx/CN nanocatalysts.

Preparation of Rh/Ni Bimetallic Nanoparticles and Their Catalytic Activities for Hydrogen Generation from Hydrolysis of KBH4

ISOBAM-104 protected Rh/Ni bimetallic nanoparticles (BNPs) of 3.1 nm in diameter were synthesized by a co-reduction method with a rapid injection of KBH4 solution. The catalytic activities of as-prepared BNPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated. Ultraviolet-visible spectrophotometry (UV-Vis), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the structure, particle size, and chemical composition of the resultant BNPs. Catalytic activities for hydrolysis of KBH4 and catalytic kinetics of prepared BNPs were also investigated. It was shown that Rh/Ni BNPs displayed much higher catalytic activities than that of Rh or Ni monometallic nanoparticles (MNPs), and the prepared Rh10Ni90 BNPs possessed the highest catalytic activities with a value of 11580 mol-H2·h−1·mol-Rh−1. The high catalytic activities of Rh/Ni BNPs could be attributed to the electron transfer effect between Rh and Ni atoms, which was confirmed by a density functional theory (DFT) calculation. The apparent activation energy for hydrogen generation of the prepared Rh10Ni90 BNPs was about 47.2 ± 2.1 kJ/mol according to a kinetic study.

Magnetic, recyclable PtyCo1−y/Ti3C2X2 (X = O, F) catalyst: a facile synthesis and enhanced catalytic activity for hydrogen generation from the hydrolysis of ammonia borane

Magnetic recyclable PtyCo1−y/Ti3C2X2 (X = O, F) catalyst exhibits excellent catalytic performance for the hydrolysis of AB at room temperature.

Inverse relation between the catalytic activity and catalyst concentration for the ruthenium(0) nanoparticles supported on xonotlite nanowire in hydrogen generation from the hydrolysis of sodium borohydride

Ruthenium(0) nanoparticles supported on xonotlite nanowire (Ru(0)/X-NW) were prepared by the ion exchange of Ru3+ ions with Ca2+ ions in the lattice of xonotlite nanowire followed by their reduction with sodium borohydride in aqueous solution at room temperature. Ru(0)/X-NW show high catalytic activity and long life time in hydrogen generation from the hydrolysis of sodium borohydride with a turnover frequency value up to 305min−1 and a total turnover number of 63,100mol H2/mol Ru in hydrogen generation from the hydrolysis of sodium borohydride at 25.0±0.1°C. Moreover, the catalytic activity of Ru(0)/X-NW shows an inverse dependence on the catalyst concentration. Ru(0)/X-NW at different ruthenium concentrations were characterized by high resolution transmission electron microscopy. The results reveal that Ru(0)/X-NW have tunable particle size depending on the metal concentration. An increase in the mean particle size of ruthenium(0) nanoparticles is observed when the metal concentration increases. The smaller particle size distribution at low ruthenium concentrations exhibits higher catalytic activity in hydrogen generation from the hydrolysis of sodium borohydride. The reaction kinetics of the catalytic hydrolysis of sodium borohydride was also studied.

N-vinyl pyrrolidone promoted aqueous-phase dehydrogenation of formic acid over PVP-stabilized Ru nanoclusters

In this work, we fabricated the poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium(0) nanoclusters by reduction of RuCl3 using different reducing agents, and studied their catalytic activity in hydrogen generation from the decomposition of formic acid. It was demonstrated that N-vinyl-2-pyrrolidone (NVP), which is a monomer of PVP, could promote the reaction by coordination with Ru nanoparticles. The Ru nanoparticles catalyst reduced by sodium borohydride (NaBH4) exhibited highest catalytic activity for the decomposition of formic acid into H2 and CO2. The turnover of numenber (TOF) value could reach 26113 h–1 at 80 °C. We believe that the effective catalysts have potential of application in hydrogen storage by formic acid.

Ceria supported rhodium nanoparticles: Superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane

We investigated the effect of various oxide supports on the catalytic activity of rhodium nanoparticles in hydrogen generation from the hydrolysis of ammonia borane. Among the oxide supports (CeO2, SiO2, Al2O3, TiO2, ZrO2, HfO2) ceria provides the highest catalytic activity for the rhodium(0) nanoparticles in the hydrolysis of ammonia borane. Rhodium(0) nanoparticles supported on nanoceria (Rh0/CeO2) were prepared by the impregnation of rhodium(III) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The catalytic activity of Rh0/CeO2 samples with various rhodium loading in the range of 0.1–4.0% wt. Rh was also tested in hydrogen generation from the hydrolysis of ammonia borane at room temperature. The highest catalytic activity was achieved by using 0.1% wt. rhodium loaded nanoceria. The resulting Rh0/CeO2 with a metal loading of 0.1% wt. Rh show superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a record turnover frequency value (TOF) of 2010min−1 at 25.0±0.1°C. The superb catalytic activity of Rh0/CeO2 is ascribed to the reducible nature of ceria. The reduction of cerium(IV) to cerium(III) leads to a build-up of negative charge on the oxide surface which favors the bonding of rhodium(0) nanoparticles on the surface and, thus, their catalytic activity. Rh0/CeO2 are also reusable catalysts preserving 67% of their initial catalytic activity even after the fifth use in hydrogen generation from the hydrolysis of ammonia borane at room temperature (TOF=1350min−1. The work reported here also includes the kinetic studies depending on the temperature to determine the activation energy (Ea=43±2kJ/mol) and the effect of catalyst concentration on the rate of hydrolysis of ammonia borane.

Hydrogen generation at ambient conditions: AgPd bimetal supported on metal–organic framework derived porous carbon as an efficient synergistic catalyst

An efficient synergistic catalyst, AgPd bimetal supported on metal–organic framework derived porous carbon (AgPd/MOF-5-C), was fabricated for the first time. The catalyst exhibited 100% H2 selectivity and high catalytic activity in hydrogen generation from formic acid at ambient conditions. The initial turnover frequency could reach as high as 854h−1. The combination of distinct interaction among bimetal, support and high dispersion of nanoparticles drastically enhances the catalytic performance of the resulted catalyst.

Ultra-thin TiO2 nanosheets decorated with Pd quantum dots for high-efficiency hydrogen production from aldehyde solution

We demonstrate that quantum-sized Pd dot-decorated ultra-thin anatase TiO2 nanosheets with exposed (001) facets exhibit a highly efficient catalytic activity for hydrogen generation from formaldehyde solution at room temperature.

Agglomerated Ag–Pd catalyst with performance for hydrogen generation from formic acid at room temperature

We report a simple method for the fabrication of agglomerated Ag–Pd nanocomposites by the addition of NaBH4. The agglomerated Ag–Pd nanocomposites are characterized SEM, TEM, XRD and XPS measurements. The prepared Ag–Pd nanocomposites exhibited catalytic activity in hydrogen generation from decomposition of formic acid at room temperature (∼25 °C). Herein, the present Ag–Pd catalysts possess the new type of agglomerated structure against to dispersion, which make them easily separated from the reaction system. It is convenient for operator to cease catalytic reaction at any moment. Moreover, the resulting Ag–Pd catalysts can be easily reactivated simply by drying after water cleaning for reuse, which saved the cost of catalysts. Among them, Ag1Pd3 sample showed nice performance of recycle test and long lifetime for the decomposition of formic acid at room temperature. We hope that this work opens a new avenue to develop solid catalysts for hydrogen production from formic acid decomposition in solution.

Skeletal Ni Catalysts Prepared from Amorphous Ni-Zr Alloys: Enhanced Catalytic Performance for Hydrogen Generation from Ammonia Borane.

Skeletal Ni catalysts were prepared from Ni-Zr alloys, which possess different chemical composition and atomic arrangements, by a combination of thermal treatment and treatment with aqueous HF. Hydrogen generation from ammonia borane over the skeletal Ni catalysts proceeded efficiently, whereas the amorphous Ni-Zr alloy was inactive. Skeletal Ni prepared from amorphous Ni30 Zr70 alloy had a higher catalytic activity than that prepared from amorphous Ni40 Zr60 and Ni50 Zr50 alloys. The atomic arrangement of the Ni-Zr alloy also strongly affected the surface structure and catalytic activities. Thermal treatment of the amorphous Ni-Zr alloys at a temperature slightly lower than the crystallization temperature led to an increase of the number of surface-exposed Ni atoms and an enhancement of the catalytic activities for hydrogen generation from ammonia borane. The skeletal Ni catalysts also showed excellent durability and recyclability.

Preparation and characterization of fishbone-like Co–B nanoparticles with high catalytic activity for hydrogen generation from NaBH4 solution

We demonstrate a facile preparation of fishbone-like Co–B nanoparticles via electroless plating method for the first time, as evidenced by XRD, SEM and AFM results. The catalytic activities of the obtained fishbone-like Co–B nanoparticles have been investigated for hydrogen generation from NaBH4 solution. The results reveal that the fishbone-like Co–B nanoparticles exhibit high catalytic activity during hydrolytic dehydrogenation of NaBH4. The hydrogen release rate and the activation energy are 10089.1mLmin−1g−1 and 34.2kJmol−1, respectively. More importantly, the fishbone-like Co–B nanoparticles have retained about 84.0% catalytic activity of its first activity after 5 cycles, which illustrates that the Co–B catalysts composed of fishbone-like catalysts show much improved reusability contrast to those common Co–B catalysts reported in the literature.

MoS2(1−x)Se2x Nanobelts for Enhanced Hydrogen Evolution

Molybdenum disulfide (MoS2) has attracted considerable attentions in the application of catalysis. However, the chemically inert property of the basal plane in MoS2 retards the catalytic efficiency. Highly exposing active edge sites and optimizing the electronic structure are the two effective ways to improve MoS2 electrocatalytic activity. Here, we report the synthesis of one dimensional (1D) single-crystal MoS2(1−x)Se2x nanobelts with controllable Se and S content, formed by the vertically aligned basal planes perpendicular to the substrate. The top and bottom surfaces of this 1D structure are fully covered by the active edge sites. The single crystalline nanobelt was characterized by high resolution transmission electron microscopy, atomic force microscopy, Raman, photoluminescence and X-ray photoemission spectroscopy. The introduction of Se into MoS2 optimizes the electronic structures of MoS2(1−x)Se2x nanobelts by tuning the oxidation state of Mo. As a result, the enhanced catalytic activity for hydrogen generation was obtained in the 1D MoS2(1−x)Se2x nanobelts (a low onset overpotential of 139mV at an electrocatalytic current density of 20mA/cm2 and a Tafel slope of 65mV/decade).

Ruthenium nanoparticles confined in SBA-15 as highly efficient catalyst for hydrolytic dehydrogenation of ammonia borane and hydrazine borane.

Ultrafine ruthenium nanoparticles (NPs) within the mesopores of the SBA-15 have been successfully prepared by using a “double solvents” method, in which n-hexane is used as a hydrophobic solvent and RuCl3 aqueous solution is used as a hydrophilic solvent. After the impregnation and reduction processes, the samples were characterized by XRD, TEM, EDX, XPS, N2 adsorption-desorption, and ICP techniques. The TEM images show that small sized Ru NPs with an average size of 3.0 ± 0.8 nm are uniformly dispersed in the mesopores of SBA-15. The as-synthesized Ru@SBA-15 nanocomposites (NCs) display exceptional catalytic activity for hydrogen generation by the hydrolysis of ammonia borane (NH3BH3, AB) and hydrazine borane (N2H4BH3, HB) at room temperature with the turnover frequency (TOF) value of 316 and 706 mol H2 (mol Ru min)−1, respectively, relatively high values reported so far for the same reaction. The activation energies (Ea) for the hydrolysis of AB and HB catalyzed by Ru@SBA-15 NCs are measured to be 34.8 ± 2 and 41.3 ± 2 kJ mol−1, respectively. Moreover, Ru@SBA-15 NCs also show satisfied durable stability for the hydrolytic dehydrogenation of AB and HB, respectively.

Hydrogen production in single chamber microbial electrolysis cells with stainless steel fiber felt cathodes

Microbial electrolysis cell (MEC) is a promising technology for sustainable production of hydrogen from biodegradable carbon sources. Employing a low-cost and high efficient cathode to replace platinum catalyzed cathode (Pt/C) for hydrogen generation is a challenge for commercialization of MEC. Here we show that a 3D macroporous stainless steel fiber felt (SSFF) with high electrochemical active surface area has an excellent catalytic activity for hydrogen generation, which is comparable to Pt/C cathode and superior to stainless steel mesh (SSM) cathode in the single-chamber MEC. The SSFF cathode (mean filter rating 100 μm) produces hydrogen at a rate of 3.66 ± 0.43 m3 H2 m−3d−1 (current density of 17.29 ± 1.68 A m−2), with a hydrogen recovery of 76.37 ± 15.04% and overall energy efficiency of 79.61 ± 13.07% at an applied voltage of 0.9 V. The performance of SSFF cathode improves over time due to a decrease in overpotential which caused by corrosion. These results demonstrate that SSFF can be a promising alternative for Pt catalytic cathode in MEC for hydrogen production.

Highly active and long lived homogeneous catalyst for the dehydrogenation of dimethylamine borane starting with ruthenium(III) acetylacetonate and oleylamine precatalyst

Herein, we report the results of our study on the homogeneous catalytic dehydrogenation of dimethylamine borane in the presence of Ru(acac)3 and oleylamine (OAm) in toluene solution. The precatalyst system comprising Ru(acac)3 and 3 equivalent OAm shows the high catalytic activity in hydrogen generation from dimethylamine borane solution. Monitoring the hydrogen evolution shows the presence of an induction period during which the homogeneous catalyst is formed, and then the hydrogen evolution continues almost linearly until the complete dehydrogenation of dimethylamine borane. UV–vis spectroscopic observation implies on the formation of a ruthenium(II) species. Using UV–vis, FTIR, Mass, 1H and 13C NMR spectroscopies we could identify the presence of trans-[Ru(acac)2(OAm)2] in the solid residue obtained after the catalytic reaction. This complex might be a stable form of the active catalyst as it shows similar catalytic activity in dehydrogenation of dimethylamine borane as before. The precatalyst system comprising Ru(acac)3 and 3 equivalent OAm provides 15,000 turnovers over 8 days with a constant turnover frequency of TOF=77.8h−1 in hydrogen generation from the dehydrogenation of dimethylamine borane in toluene solution at 60.0±0.1°C. Adding 3 equivalent OAm per Ru into the precatalyst solution increases the catalytic activity by a factor of ∼5 and the lifetime of the catalyst by a factor of >9 compared to the ones obtained by using sole Ru(acac)3. Kinetics of catalytic dehydrogenation of dimethylamine borane starting with Ru(acac)3 and 3 equivalent OAm in toluene solution were studied depending on catalyst concentration, substrate concentration and temperature. The catalytic reaction was found to be first-order with respect to each of both Ru(acac)3 and dimethylamine borane concentrations. The activation energy for the catalytic dehydrogenation is Ea=58±2kJ/mol.

Controlled synthesis of monodisperse PdxSn100−x nanoparticles and their catalytic activity for hydrogen generation from the hydrolysis of ammonia-borane

Composition controllable monodisperse palladium tin nanoparticles (PdxSn100−x NPs, x = 77, 69, 63, 52, 49) were prepared by the thermal reduction of palladium bromide and tin acetate in the presence of trioctylphosphine and oleylamine. The NPs were investigated for their catalytic abilities of hydrogen generation from hydrolysis of ammonia borane complex. Deposited on a carbon support without any further treatment, these NPs were active nanocatalysts for hydrolysis of ammonia borane complex, and their catalytic activities were highly composition dependent. Among these NPs studied, Pd69Sn31 NPs exhibited the highest catalytic activity and stability under mild reaction conditions. Kinetic investigations showed that the catalytic hydrolysis of ammonia borane was first-order with respect to catalyst concentration and zero-order with respect to ammonia borane concentration. The activation energy for the hydrolysis of ammonia borane complex in the presence of Pd69Sn31 NPs was calculated to be 27.22 kJ mol−1. The PdxSn100−x NPs are promising candidates toward the practical development of the ammonia borane complex as a feasible hydrogen storage medium for fuel cell applications under ambient conditions.