Hydrolytic Dehydrogenation Research Articles

Controllably hydrolytic dehydrogenation of NH3BH3 over micropore-dominant porous carbon confined RuPd ultrafine alloys

At present, controllable producing hydrogen from the catalytic hydrolysis of ammonia borane (AB, NH3BH3) is very meaningful and challenging. Therefore, developing an effective catalyst for the reaction, clarifying its catalytic mechanism, and realizing controllable hydrogen release are extremely indispensable. In this work, RuPd nanoalloys are evenly confined by the agricultural waste wheat straw-derived carbon (denoted as WSC) with a micropore-dominant porous structure and plentiful N/O doping. Attributing to the particular support effect of WSC and the interesting RuPd alloy effect, the as-prepared bimetallic catalysts provide encouraging catalytic performance in AB hydrolysis. Catalyzed by the optimal Ru0.50Pd0.50@WSC, the turnover frequency (TOF) and hydrogen evolution rate are 214.5 min−1 and 50800 mL min−1 g−1, respectively, and the apparent activation energy is only 23.2 kJ mol−1. Moreover, introducing proper NaOH (1.5 M) further accelerates hydrogen release (TOF = 502.8 min−1, specific rate = 119100 mL min−1 g−1). The isotope experiments depict a kinetic isotope effect of 2.85, evidencing the vital role of the hydrogen–oxygen bond scission in this catalytic reaction. More importantly, benefitting from the difference in adsorption energy and strong coordination ability, the “on–off” control for the hydrolysis of AB over Ru0.50Pd0.50@WSC can be realized with the Zn2+/EDTA2- system. This study provides an attractive metal alloy catalyst and some insights for the controllable hydrolysis of AB.

Efficient hydrolytic dehydrogenation of ammonia borane catalyzed by ultrafine Pt clusters confined in Ni–Ti layered double hydroxides with closo-dodecaborate

Ammonia borane (NH3BH3, AB) is a highly promising candidate for hydrogen storage. Nevertheless, there is an urgent need to develop an efficient and stable catalyst that can control hydrogen generation under mild conditions. The use of catalysts with numerous surface atoms anchored to a carrier to achieve a synergistic effect is an appealing approach in catalysis. In this work, a series of highly dispersed metal clusters NiTi-LDH@B12H12@M (M = Au, Pd, Pt, Ag) catalysts were successfully synthesized at room temperature by leveraging the reductivity of [closo-B12H12]2- immobilized in the layered double hydroxide (LDH) laminate, along with the spatial confinement and anion exchange capabilities of LDH. Specifically, utilizing the optimal catalyst NiTi-LDH@B12H12@Pt 2.4% (wt. Pt), the AB hydrolysis reaction exhibited extraordinary catalytic activity. It exhibited a first-order reaction rate with respect to Pt and a near zero-order reaction rate with respect to AB concentration. The AB hydrolysis can be achieved in a mere 29 s at 25 °C with a conversion rate of 100%. The corresponding turnover frequency (TOF) attains a value of 454.06 molH2molPtmin−1, and the apparent activation energy (Ea) is 41.8 kJ mol−1, surpassing numerous previously reported Pt-based catalysts. The outstanding catalytic performance can be ascribed to the uniform distribution of ultrafine Pt clusters, along with the synergistic effect conferred by NiTi-LDH and intercalated anions ([closo-B12H12]2-).

Metal-organic framework-derived carbon-supported high-entropy alloy nanoparticles applied in ammonia borane hydrolytic dehydrogenation

While high-entropy alloy nanoparticle (HEA NP) catalysts from a sacrificial high-entropy-MOF (HE-MOF) have been attractive, their conventional characterizations may be misleading. Here, we report HEA NPs on HE-MOF-derived carbon (HE-MDC) via direct pyrolysis of MnFeCoNiCu HE-MOF in Ar and H2 at different temperatures and durations with a fast-ramping rate. With the profound investigations of the metal NPs on HE-MDCs by synchrotron radiation X-ray diffraction and absorption, we revealed that the Ar-treated HE-MDCs had either Cu-dominant solid solution or phase-segregated metal NPs, whereas H2 pyrolysis yielded well-dispersed HEA NPs on HE-MDCs. For ammonia borane hydrolysis, although the metal NP size in H2-treated HE-MDC was not the smallest, it showed the fastest dehydrogenation rate (TOF=5.76 molH₂∙min−1∙molcat-1), 2 ∼ 4 times faster than the Ar-treated HE-MDCs. It emphasized the crucial role of elemental uniformity in the HEA NPs over the traditionally reported catalyst size.

Tailoring the interfacial electron redistribution of ball-in-ball structured CuO-Co3O4 nanocomposites for synergistic enhancement in hydrolytic dehydrogenation of ammonia borane

Construction of high-efficiency and affordable catalysts for hydrogen production from hydrolysis of ammonia borane is highly desirable, but significant challenges still exist. In this study, a series of ball-in-ball hollow structured CuO-Co3O4 nanocomposites with varied Cu/Co molar ratio were constructed via simple solvothermal method combined with a post-calcination. The CuO-Co3O4 composite featuring a Cu/Co molar ratio of 1: 2 displayed the highest catalytic efficiency, achieving a turnover frequency (TOF) value of 25.0 molH2 molcat.−1 min−1 for AB hydrolysis. An evident synergistic enhancement in catalytic activity was confirmed between CuO and Co3O4. Experimental and theoretical researches uncovered that the enhancement of activity is originated from the electron transfer between Cu and Co ingredients, which is beneficial for the adsorption and activation of H2O and ammonia borane. In addition, the DFT calculations results revealed that the actual active sites for AB hydrolysis in CuO-Co3O4 composite catalyst is the Co site. These findings should provide some insightful recommendations for designing robust and cost-effective composite catalysts for the hydrolytic dehydrogenation of ammonia borane.

Oxide coated nickel powder as support for platinum(0) nanoparticles: Magnetically separable catalysts for hydrogen generation from the hydrolysis of ammonia borane

We report the development of a novel method for the preparation of magnetically separable platinum nanoparticles. Magnetic nickel nanopowder is initially synthesized in a radiofrequency plasma reactor where in-line passivation was carried out with oxygen gas, resulting in the formation of nickel oxidecoated nickel particles. Following this, platinum nanoparticles are deposited onto the surface of the oxidecoated nickel nanopowder, forming Pt0/Ni@NiO nanocatalysts for the hydrolytic dehydrogenation of ammonia borane. The Pt0/Ni@NiO nanoparticles, containing 0.24 % wt. Pt, exhibit remarkable catalytic activity in the hydrolytic dehydrogenation of ammonia borane, with a turnover frequency of 468 (mol H2)×(mol Pt)−1×min−1 for releasing 3 equivalent H2 gas per mole of ammonia borane from its hydrolysis at 25 ºC. This heightened catalytic activity of Pt0/Ni@NiO nanoparticles is attributed to the favorable metal-support interaction between the platinum(0) nanoparticles and oxide surface, namely the bonding of platinum to the oxide surface, as elucidated by the XPS analysis. More importantly, Pt0/Ni@NiO nanoparticles can be separated from the reaction solution by using an external magnet.

Coupling geometric and electronic engineering over RuNi ultrafine alloys for fast boosting hydrolytic dehydrogenation of NH3BH3

Developing a suitable catalyst for ammonia borane (AB, NH3BH3) hydrolysis and clarifying the catalytic mechanism are essential and challenging at present. In this work, RuNi nanoalloys are supported on an N/O co-coped glucose-derived carbon (g-C) with the adsorption-NaBH4 reduction method. Attributed to the particular geometric and anchoring effects, as well as the improved hydrophilicity of the multi-level porous support, the RuNi alloys are highly and firmly confined in the framework of g-C. Specifically, the optimal Ru0.25Ni0.75@g-C with an average alloy particle size of 1.4 nm exhibits pleasurable specific hydrogen evolution rate (437,990 mL min−1 gRu−1) and turnover frequency (1612.37 min−1) in NaOH aqueous solution (1.5 M) at 303 K, superior to the corresponding monometallic counterparts (i.e., Ni@g-C and Ru@g-C) and many previous results. In addition, apart from satisfactory durability, the optimal alloy catalyst delivers an encouraging apparent activation energy (28.1 kJ mol−1). Our work not only explains the geometric and electronic effects on the catalytic performance but also offers a promising catalyst for hydrogen release from liquid-phase AB.

Novel nanoporous amorphous/nanocrystalline composite structured RuNiFeCo multicomponent alloys with exceptional catalytic activity for ammonia borane hydrolytic dehydrogenation

The pursuit of high-efficient and cost-effective catalysts for hydrogen generation is imperative to address the energy crisis. Herein, nanoporous RuNiFeCo alloys (np-RuNiFeCo) with high catalytic activity for ammonia borane (AB) hydrolytic dehydrogenation have been prepared by dealloying Fe25NixCo40-xRu5B30 (x = 0–40) high-entropy amorphous alloys with low Ru content. The np-RuNiFeCo are composed of an amorphous/hexagonal close-packed Ru nanocrystalline dual-phase structure and exhibit a uniform nanopore/ligament bicontinuous architecture. The morphology, composition, and AB hydrolysis catalytic properties of the np-RuNiFeCo can be regulated by varying the Ni/Co content in the precursors, and the best catalytic activity with a high turnover frequency value of 148.2 molH2molRu‐1min‐1 and a low apparent activation energy of 25.3 kJmol‐1 was obtained when x = 30. Density functional theory simulations indicate that the presence of Ni, synergizing with Fe and Co, promotes electron transfer to Ru and enhances the adsorption energies of both AB and H2O molecules while reducing the activation barrier for cleaving the H2O molecule, leading to enhanced intrinsic catalytic activity of the alloy. The exceptional catalytic performance of the np-RuNiFeCo arises from the synergy of multiple principal elements, nanoporous morphology, and amorphous/nanocrystalline heterogeneous interface. In addition, the mechanisms of dealloying and nanoporous structure formation have been discussed based on surface diffusion.

Two-dimensional molybdenum boride coordinating with ruthenium nanoparticles to boost hydrogen generation from hydrolytic dehydrogenation of ammonia borane

The coordination between carrier and active metal is critical to the catalytic efficiency of ammonia borane (AB) hydrolysis reaction. In the present study, we report a new type of catalytic support based on molybdenum boride (MBene) MoAl1-xB and demonstrate that the effective combination of MoAl1-xB with Ru nanoparticles can realize the significantly enhanced performance for hydrogen generation. Owing to the efficient activation and dissociation of reactants, the optimal Ru/MoAl1-xB catalyst achieves the large turnover frequency of 494 molH2 molRu-1 min−1, high hydrogen generation rate of 119817 mL min−1 gRu-1 and favorable apparent activation energy of 39.2 kJ mol−1 for the catalytic hydrolysis of AB under alkaline-free condition. The isotopic test suggests the cleavage of OH bond in H2O is the rate-determining step for hydrolysis reaction, while the fracture of B–H bond in AB is also well revealed by attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy. Significantly, the flexible on-demand hydrogen generation is achieved by using chemical switches for on–off AB hydrolysis. This study provides a new support platform based on two-dimensional MBene to exploit efficient catalysts to boost AB dehydrogenation.

Ultrafine Ni-MoOx Nanoparticles Anchored on Nitrogen-Doped Carbon Nanosheets: A Highly Efficient Noble-Metal-Free Catalyst for Ammonia Borane Hydrolysis.

The development of low-cost and high-efficiency catalysts for the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3) is still a challenging technology. Herein, ultrafine MoOx-doped Ni nanoparticles (~3.0 nm) were anchored on g-C3N4@glucose-derived nitrogen-doped carbon nanosheets via a phosphate-mediated method. The strong adsorption of phosphate-mediated nitrogen-doped carbon nanosheets (PNCS) for metal ions is a key factor for the preparation of ultrasmall Ni nanoparticles (NPs). Notably, the alkaline environment formed by the reduction of metal ions removes the phosphate from the PNCS surface to generate P-free (P)NCS so that the phosphate does not participate in the subsequent catalytic reaction. The synthesized Ni-MoOx/(P)NCS catalysts exhibited outstanding catalytic properties for the hydrolysis of AB, with a high turnover frequency (TOF) value of up to 85.7 min-1, comparable to the most efficient noble-metal-free catalysts and commercial Pt/C catalyst ever reported for catalytic hydrogen production from AB hydrolysis. The superior performance of Ni-MoOx/(P)NCS can be ascribed to its well-dispersed ultrafine metal NPs, abundant surface basic sites, and electron-rich nickel species induced by strong electronic interactions between Ni-MoOx and (P)NCS. The strategy of combining multiple modification measures adopted in this study provides new insights into the development of economical and high-efficiency noble-metal-free catalysts for energy catalysis applications.

Exploring Enhanced Hydrolytic Dehydrogenation of Ammonia Borane with Porous Graphene-Supported Platinum Catalysts.

Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted graphene, in a form with multiple layers, decreases the practical specific surface area. Building pores in graphene can increase specific surface area and provide anchor sites for catalysts. In this study, we have prepared porous graphene (PG) via the process of equilibrium precipitation followed by carbothermal reduction of ZnO. During the equilibrium precipitation process, hydrolyzed N,N-dimethylformamide sluggishly generates hydroxyl groups which transform Zn2+ into amorphous ZnO nanodots anchored on reduced graphene oxide. After carbothermal reduction of zinc oxide, micropores are formed in PG. When the Zn2+ feeding amount is 0.12 mmol, the average size of the Pt nanoparticles on PG in the catalyst is 7.25 nm. The resulting Pt/PG exhibited the highest turnover frequency of 511.6 min-1 for ammonia borane hydrolysis, which is 2.43 times that for Pt on graphene without the addition of Zn2+. Therefore, PG treated via equilibrium precipitation and subsequent carbothermal reduction can serve as an effective support for the catalytic hydrolysis of ammonia borane.

NiPdMo nanoparticles reduced by Cs[closo-B6H7] as high-performance catalysts for hydrogen generation from hydrolysis of ammonia borane

The synthesis of efficient catalysts for the hydrolysis of ammonia borane (NH3BH3, AB) is a matter of critical importance and immediate necessity, as it is currently considered a promising approach for the production of hydrogen. The synergy of interactions between different metals has been widely applied in the hydrolysis of AB. In this work, we first applied Cs [closo-B6H7] as the reductant to prepare a series of NixPdyMoz NPs catalysts using a simple in-situ reduction method. The structural and physical chemical properties of the as-prepared catalysts are investigated employing a multitude of various characterizations. Utilizing the optimal catalyst Ni0·3Pd0·7Mo0.2 NPs, AB hydrolysis can be completed at room temperature in just 21 s. This catalyst exhibits a lower activation energy (Ea = 52.3 kJ mol−1) and relatively higher activity (TOF = 252.7 mmolH2·mmolmetal−1min−1), which greatly outperforms many previously reported similar or corresponding catalysts. The enhancement in catalytic activity is ascribed to the moderate reducibility of Cs [closo-B6H7] and the synergistic interaction among Ni, Pd, and Mo. These results suggest the promise of multi-metal catalysts derived from Cs [closo-B6H7] for the hydrolytic dehydrogenation of hydrogen storage materials.

Desirable performance and mechanism of RuPd nanoalloys in catalyzing hydrolytic dehydrogenation of NH3BH3

The dehydrogenation of liquid-phase chemical hydrogen storage materials (such as ammonia borane, AB, NH3BH3) is a promising strategy to develop the promising hydrogen economy. Considering that the self-hydrolysis of AB is nearly impossible at room temperature, it is very worthwhile to search a robust catalyst for this hydrolytic reaction and clarify the catalytic mechanism. In this work, a glucose-derived N/O co-doped and multi-level porous carbon (marked as g-pC, SBET = 1356 m2 g−1, Vtotal = 0.762 cm3 g−1, Smicro = 1079 m2 g−1, Vmicro = 0.427 cm3 g−1) is prepared for confining RuPd alloys. Benefitting from the positive effect of g-pC (such as the particular anchoring and geometric effects on highly and tightly confining RuPd nanoparticles, as well as enhanced hydrophilicity) and the exceptional metal alloy effect, the obtained bimetallic catalysts unveil drastically enhanced catalytic activity in AB hydrolysis compared to the monometallic counterparts. Especially, catalyzed by the optimal Ru0.25Pd0.75@g-pC with a mean alloy size of 1.5 nm (10 mg), the dehydrogenation of 1.00 mmol AB can be finished within 1 min at 303 K in NaOH solution (1.5 M). The corresponding turnover frequency and hydrogen generation rate are calculated to be 541.09 min−1 and 145,950 mL min−1 g−1, respectively. Moreover, about 62% of the initial catalytic activity is still retained even in the 18th cyclic experiment, suggesting the extraordinarily long durability. In addition, the isotopic analyses present a kinetic isotope effect (KIE) of 3.38, further confirming that the scission of an O-H bond in H2O is the rate-controlling step in this hydrolytic reaction. Our work offers a competitive metal alloy catalyst for generating hydrogen from AB aqueous solution and promote the development and safety utilization of hydrogen energy.

Double-plasmonic-coupled heterojunction photocatalysts for highly-efficient full-spectrum-light-driven H2 evolution from ammonia borane

Methods to enhance the full-spectrum-light-driven water splitting for H2 evolution remain one of the critically important issues to explore advanced photocatalysts. In this study, we present a novel double-plasmon-coupled semiconductor heterojunction photocatalyst with a large number of oxygen vacancies, produced via a simple two-step solvothermal process. These materials represent a new model system to study the kinetics process and catalytic activity of ammonia borane hydrolytic dehydrogenation in a full-spectrum-light-driven plasmonic semiconductor heterostructure. Upon irradiation with full-spectrum light, the resultant photocatalysts are capable of delivering H2 generation rate up to 13,031 μmol g-1h−1, which is ∼6 times greater than that of pristine MoO3-x counterpart. The excellent photocatalytic behavior is primarily attributed to the improved carrier separation, increased light absorption, and enhanced generation of “hot electrons”, enabled by a synergistic photo- and thermo-catalytic effect. Consequently, the high performance of the novel photocatalyst derives from the design of a double-plasmonic-coupling effect and the photocatalyst containing Type-Ⅱ heterojunctions.

Controllable hydrogen release from NH3BH3 hydrolysis over Ru ultrafine particles stabilized on agriculture waste-derived carbon

Simultaneously considering cost, safety and catalytic efficiency, the development of a cost-effective and high-performance catalyst is significant and challenging for controllable hydrogen release from ammonia borane (AB, NH3BH3) hydrolysis. In this work, Ru ultrafine particles are evenly and firmly stabilized on wheat straw-derived porous carbon through a facile procedure. Specifically, attributed to the abundant co-doping of heteroatoms (namely, N and O) and suitable hierarchical porous structure of WSC-1.0 with large specific surface area (1000 m2 g−1), which is prepared with a mass ratio of 1: 1 for K2CO3 to the pre-carbonized biomass waste, as well as high dispersion (32.6%) of Ru ultrafine particles with an average size of 1.4 ± 0.3 nm, the optimal Ru/WSC-1.0 displays exceptional catalytic performance in the hydrolysis of AB. The corresponding turnover frequency (TOF) and specific reaction rate (rB) are 167.7 min−1 and 4.07 × 104 mL min−1 gRu−1, respectively, and the apparent activation energy is 40.94 kJ mol−1. Upon adding NaOH (1.0 M), the hydrolysis rate can be remarkably accelerated (TOF = 401.4 min−1, rB = 9.75 × 104 mL min−1 gRu−1). The isotope experiments show that the scission of an O-H bond in H2O by oxidative addition is the decisive step in this reaction. Impressively, the effective “on-off” control for the hydrolytic dehydrogenation reaction over Ru/WSC-1.0 can be easily realized by introducing certain amounts of Zn(NO3)2 and EDTA-2Na, separately. Our work delivers a facile approach for efficient utilization of agricultural wastes and offers a robust and cost-effective catalyst for the controllable hydrogen evolution from AB hydrolysis.

CoNi Nanoparticles Supported on Hierarchical SAPO-34 Zeolite as a Catalyst for the Hydrolytic Dehydrogenation of Ammonia Borane

CoNi Nanoparticles Supported on Hierarchical SAPO-34 Zeolite as a Catalyst for the Hydrolytic Dehydrogenation of Ammonia Borane

An evidence for electron transfer of hydrolytic dehydrogenation of ammonia borane over ruthenium ultra-fine nanoparticles

Hydrogen production from ammonia-borane hydrolysis has been widely studied for its high efficiency and many catalytic mechanisms with different viewpoints have been proposed. However, no attention has been paid to electron transfer during catalytic reactions to form H2 in these catalytic mechanisms. In the present contribution, we propose two possible electron transfer pathways for hydrogen production from AB hydrolysis, which were validated by hydrogen evolution reaction (HER) tests. The electrochemical characterization correlates with the AB hydrolysis test results, where Ru4/Fe–N–C catalyst has the largest active surface area and the smallest charge transfer resistance, along with the largest turnover frequency (298.7 molH2 molRu−1 min−1). These results indicate that Ru4/Fe–N–C catalyst not only provides the adsorption/desorption sites but also provides an effective approach for electron transfer in hydrogen production from AB hydrolysis.

Reducible tungsten(VI) oxide-supported ruthenium(0) nanoparticles: highly active catalyst for hydrolytic dehydrogenation of ammonia borane.

Reducible WO3 powder with a mean diameter of 100 nm is used as support to stabilize ruthenium(0) nanoparticles. Ruthenium(0) nanoparticles are obtained by NaBH4 reduction of ruthenium(III) precursor on the surface of WO3 support at room temperature. Ruthenium(0) nanoparticles are uniformly dispersed on the surface of tungsten(VI) oxide. The obtained Ru0/WO3 nanoparticles are found to be active catalysts in hydrolytic dehydrogenation of ammonia borane. The turnover frequency (TOF) values of the Ru0/WO3 nanocatalysts with the metal loading of 1.0%, 2.0%, and 3.0% wt. Ru are 122, 106, and 83 min-1, respectively, in releasing hydrogen gas from the hydrolysis of ammonia borane at 25.0 °C. As the Ru0/WO3 (1.0% wt. Ru) nanocatalyst with an average particle size of 2.6 nm provides the highest activity among them, it is extensively investigated. Although the Ru0/WO3 (1.0% wt. Ru) nanocatalyst is not magnetically separable, it has extremely high reusability in the hydrolysis reaction as it preserves 100% of initial catalytic activity even after the 5th run of hydrolysis. The high activity and reusability of Ru0/WO3 (1.0% wt. Ru) nanocatalyst are attributed to the favorable metal-support interaction between the ruthenium(0) nanoparticles and the reducible tungsten(VI) oxide. The high catalytic activity and high stability of Ru0/WO3 nanoparticles increase the catalytic efficiency of precious ruthenium in hydrolytic dehydrogenation of ammonia borane.

When Pt nanoparticles meet oxygen-deficient Co3O4: Enabling superior performance towards on-demand hydrogen generation from hydrolytic dehydrogenation of dimethylamine borane

The regulation of the metal-support interaction in heterogeneous catalysts can promote the activation of reactants, which is beneficial for the hydrolytic dehydrogenation reaction. Herein, the hydrolytic dehydrogenation of dimethylamine borane (DMAB) is systematically studied on the oxygen vacancy (Ov) enriched Pt-Co3O4 heterogeneous catalyst with the metal-support interaction. It is found that the metallic Pt site facilitates the adsorption of DMAB molecules and the Ov on Co3O4 support as an electron-rich center cooperates with the adjacent Pt site to dissociate water molecules. The in situ Raman and attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy reveal the effective activation and cleavage of the O-H in water and the B-H in DMAB over the Pt-Co3O4 catalyst. The optimal Pt-Co3O4 catalyst exhibits the extraordinary activity for the catalytic hydrolysis of DMAB at 303 K, delivering a high specific hydrogen generation rate (64063 mL min−1 gpt−1) and a competitive turnover frequency (TOF, 23880 molH2 molPt−1 h−1). This performance outperforms most of the reported heterogeneous catalysts for DMAB dehydrogenation. More importantly, the Pt-Co3O4 catalyst achieves the desirable on-demand hydrogen production by using special chemical switches. This finding provides the fundamental understanding of metal-oxide systems with the collaborative interfacial catalysis for boosting DMAB dehydrogenation.

Cobalt-free CuO catalyst for hydrolytic dehydrogenation of sodium borohydride and ammonia borane

The environmental and economic impact of Co-based catalysts necessitates the use of a more environmentally friendly and less expensive catalyst, such as CuO. A cobalt-free CuO catalyst was developed via a simple low-temperature hydrothermal process. The efficiency of the catalyst was analysed for the dehydrogenation of NaBH4 as well as NH3BH3. Compared with the commercial particulate CuO, hydrothermally prepared CuO nanoplate (CuO HT) exhibits a good hydrogen evolution rate, the rate of hydrogen evolution for CuO_Commercial and CuO HT was experimentally measured to be 240 ml H2/min/g and 470.5 ml H2/min/g respectively for 0.2 g catalyst for the dehydrogenation of NaBH4. At a 10 times lower concentration of NaBH4 with 0.2 g of CuO HT catalyst, the rate of HER recorded was 1086 ml H2/min/g. The high catalytic activity of CuO HT could be related to the surface oxygen vacancies or defects generated due to the participation of high molar concentrations of NaOH during the reaction. The stability of both catalysts was investigated, and the rate of hydrogen evolution reaction after three cycles was determined to be 492 ml H2/min/g for CuO_Commercial and 925.1 ml H2/min/g for CuO HT. Despite the fact that the rate of hydrogen evolution was observed to be increased for the third cycle, the volume of water displaced was decreased when compared to the first cycle, which could be due to the presence of a less active Cu2O phase retained after temperature treatment. Similarly, with the best catalyst concentration of CuO HT (0.2 g), the hydrogen evolution rate of NH3BH3 was also measured to be 1175 ml H2/min/gm. The result evokes a new insight into the evolution of sustainable and eco-friendly catalysts for a better hydrogen economy.

Co–Fe–B@g-C3N4/Cu sheet for promoting hydrolytic dehydrogenation from the hydrolysis of NaBH4 solution

In this work, Co–Fe–B@g-C3N4/Cu sheet has been successfully prepared via chemical deposition process. When the weight of g-C3N4 is optimized to 0.005 g, the as-obtained catalyst with unique surface structure shows an improved catalytic performance toward the hydrolysis of NaBH4 solution. Under visible light irradiation, HGR of 8343 mL·min−1·g−1 and Ea of 48.4 kJ·mol−1 are synchronously accomplished. The results indicate that the catalytic activity has surpassed most of reported non-precious metal and even precious metal catalysts. It demonstrates that this work offers a viable method for manufacturing non-noble metal catalysts with high catalytic property toward the hydrolysis of NaBH4 solution.