NaBH4 Hydrolysis Research Articles

Magnetic recyclable catalysts with dual protection of hollow Co/N/C framework and surface carbon film for hydrogen production from NaBH4 hydrolysis

NaBH4 (10.8 wt% theoretical hydrogen storage capacity) is an ideal hydrogen carrier, but its hydrolysis reaction at room temperature requires high-efficiency catalysts for activation and acceleration. Structured catalysts can effectively inhibit metal particle agglomeration. However, metal particles fall off the surface of the support during testing. Therefore, we report a magnetic recyclable hollow shell material H-Co/N/C-Ru@C-T. The dual protection of carbonized ZIF-67 as a framework and surface-coated carbon film makes it show good catalytic activity and durability in NaBH4 hydrolysis reaction. The hydrogen generation rate (HGR) is as high as 9815.82 mLH2 min−1 g−1, and the activation energy (Ea) is reduced to 26.9 kJ mol−1. Moreover, it retains 81.3% of its initial catalytic activity even after 25 hydrolysis cycles. Through a series of characterization, such as electron scanning spectroscopy and inductively coupled plasma atomic emission, the improvement effect of using hollow Co/N/C as framework and coating carbon film on surface on the catalytic activity and durability of H-Co/N/C-Ru@C-650 is systematically revealed. We believe this work is of unusual significance on exploring novel hydrogen storage material catalysts, especially providing opportunities for the improvement of catalytic activity and durability of catalysts.

Controllable hydrogen production from NaBH4 hydrolysis promoted by acetic acid

Numerous catalysts have been widely investigated for accelerating hydrogen production from NaBH4 hydrolysis. However, these catalysts are usually complicated in structures, costly in fabrication, and hazardous for environment. In this work, cheap and environment-friendly acetic acid, CH3COOH, is employed to promote NaBH4 hydrolysis to produce hydrogen in a considerable rate. The experimental results demonstrate that the addition of suitable amount of CH3COOH into NaBH4 solutions stabilized with NaOH could dramatically accelerate the hydrolysis reaction. Additionally, the start/stop of NaBH4 hydrolysis could be controlled by adding acid or base into the solution to realize “go-as-you-please” on-site hydrogen production.

Co3O4 Nanowires Decorated with BOx Species for Electrocatalytic Oxygen Evolution

One-dimensional nanowires possess significant advantages in active site exposure and electron and matter transport. Their oxygen evolution reaction (OER) performances can be well enhanced by the introduction of oxygen vacancies (Ov) and boron element (B), which, however, have not been achieved simultaneously. Herein, the Ov and BOx motifs were simultaneously employed in typical cobalt spinel oxide nanowires via simple NaBH4 hydrolysis (Co3O4/BOx). When grown on carbon fiber cloth, the observed Co3O4/BOx nanowire array electrode drives a current density of 10 mA cm–2 with only 328 mV overpotential in a 1.0 M KOH solution, which is much superior to the spinel Co3O4. We found that the BOx motifs and Ov have efficiently tuned electronic structures of Co3O4, thereby enhancing the electrical conductivity and generating a large number of electroactive sites. This study provides a simple solution for designing and producing nanostructure OER catalysts with excellent electrochemical performance.

Modified CNTs interfacial anchoring and particle-controlled synthesis of amorphous cobalt-nickel-boron alloy bifunctional materials for NaBH4 hydrolysis and supercapacitor energy storage

The advantage of composites comes from the synergy between different material, that is, the engineering of interface effects between them. Well-developed surface effects between the materials help to maximize the properties and improve the stability of the composite. Herein, CoNiB@ca-CNTs composites were successfully prepared through a simple wet chemical reduction method by reducing the metal ions pre-anchored on the surface of carboxylated modified CNTs. Co0.25Ni0.75B@ca-CNTs composite were used as electrode materials for supercapacitor. It provides high specific capacitance (2078 F g−1 under 1 A g−1), outstanding rate performance (1802 F g−1 under 10 A g−1), and good cycling stability (87.8% retention rate at 5000 cycles). The constructed Co0.25Ni0.75B@ca-CNTs//AC (activated carbon) asymmetric supercapacitor obtained 180.3 F g−1 under 1 A g−1. It has an energy density of 67.4 Wh kg−1 at 400.4 W kg−1 and good stability (84.1% retention at 5000 cycles). In addition, Co0.75Ni0.25B@CNTs was used as catalyst with excellent catalytic activity for the hydrolysis of NaBH4, with hydrogen production rates of 6245.75 mL min−1 gcatalyst−1 and 18135.16 mL min−1 gCo,Ni−1 at 25 °C and low activation of 28.67 kJ mol−1. It has good catalytic stability remaining 72.6% after 10 catalytic hydrolysis cycles. The results demonstrate that CoNiB@ca-CNTs exhibit excellent performance and stability in the field of supercapacitors and hydrogen production from NaBH4 hydrolysis. This work has a good inspiration for the development of bifunctional composite materials in the future.

Ultrasmall bimetallic Ru-Co alloy nanoclusters immobilized in amino-functionalized UiO-66 and N-doped carbonaceous zirconium oxide nanocomposite for hydrogen generation

To satisfy global energy demands and maintain sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. H 2 generation from hydrolysis of NaBH 4 represents as a safe and convenient method for storing and releasing H 2 . The free amine groups (NH 2 ) and the big pores in the NH 2 -UiO-66 metal-organic framework were exploited to encapsulate ultrasmall bimetallic Ru-Co alloy nanoclusters and monometallic Ru and Co nanoclusters with an average particle size of 1.5 nm via direct anionic exchange technique. To prove the role of the NH 2 groups and the MOF’s pores in the creation of a well and uniform-dispersed ruthenium and cobalt nanoclusters, the NH 2 -UiO-66 was calcined at 600 °C for 3 h in the air to prepare N-doped carbonaceous ZrO 2 (ZrO 2 N @ C) nanocomposite. Hydrazine hydrate (HH) was used as a reducing agent in the presence of microwave irradiation (MWI). The prepared catalysts were used as novel catalysts for hydrogen generation, via the hydrolysis of sodium borohydride (NaBH 4 ). 2 wt% Ru-Co/NH 2 -UiO-66 displays a high hydrogen generation rate (HGR) of 10526 mL H 2 g −1 min −1 from low concentration NaBH 4 solution (50 mM). The extraordinary catalytic activity of the prepared catalysts attributes to the ultrasmall particle size of the ruthenium and cobalt nanoclusters in the MOF’s pores, the synergistic harmony between the Ru and Co nanoclusters in the alloy form, and the large surface area of the NH 2 -UiO-66. The effect of the NaBH 4 concentration, catalyst amount, and reaction temperatures (30–60 °C) was investigated. The catalyst shows high recyclability efficiency for at least five cycles, due to the high leaching resistance of the alloy nanoclusters within the MOF host. The prepared catalysts may be considered as highly efficient catalysts for energy-based applications. • Preparation of ultrasmall single alloy Ru-Co nanoclusters without ligand. • The free amine groups in the NH 2 -UiO-66 provide coordination sites for metal ions. • Synthesis of N-doped carbonaceous ZrO 2 (ZrO 2 N @ C) derived from NH 2 -UiO-66. • Reduction of Ru and Co ions with hydrazine hydrate under MWI. • Ru-Co/NH 2 -UiO-66 achieves a high hydrogen generation rate of 10526 mL g cat −1 min −1 .

Electronic transfer enhanced coral-like CoxP loaded Ru nanoclusters as efficient catalyst for hydrogen generation via NaBH4 hydrolysis

The slow kinetics of NaBH4 hydrolysis to generate hydrogen can be effectively improved by designing the composite catalysts of precious metals and transition metals, while their micro-combined structure still needs to be improved. Herein, the coral-like CoxP with high specific surface area is fabricated by ZIF-67 in-situ etching, annealing, phosphating and loading in turns, 1.5 nm Ru nanocluster species are uniformly loaded on the skeleton surface of CoxP, and there is the strong electronic effect between Ru and CoxP. By further adjusting the loading of Ru, the optimized Ru3.4@CoxP catalyst has lower activation energy (32.8 kJ mol−1) than CoxP, and displays higher turnover frequency (606molH2min−1molRu−1) and hydrogen generation rate (4551mLmin−1gcatalyst−1) than the comparative and most reported similar catalysts during NaBH4 hydrolysis. Furthermore, After five cycles, the catalytic activity of Ru3.4@CoxP is only reduced by 25.6%. The excellent catalytic activity is due to the micro-nano structure with high specific surface area and the synergistic effect between Ru and Co species providing more catalytic active sites, which is the precise and controllable design method for developing noble metal/transition metal composite catalyst.

In situ evolved defective TiO2 as robust support for CoB-catalyzed hydrolysis of NaBH4

Sodium borohydride (NaBH4) has been proposed to be a realizable hydrogen supplier for proton-exchange membrane fuel cell. Cobalt boride (CoB) is one of the most promising non-precious metal-based catalysts toward NaBH4 hydrolysis. In this work, we develop a facile method to synthesize defects-rich TiO2 supported CoB nanoparticles (CoB/TiO2-x). In this CoB/TiO2-x, an electronic metal-support interaction is induced by transferring electrons from the defective TiO2 to CoB to form electron-rich CoB particles, facilitating the hydrolysis of NaBH4. The as-synthesized CoB/TiO2-x catalyst shows a good catalytic performance with hydrogen generation rate of 3070 mL min−1 gCo−1 and activation energy of 57.03 kJ mol−1.

Catalytic hydrolysis of sodium borohydride for hydrogen production using phosphorylated silica particles.

Hydrolysis of sodium borohydride (NaBH4) offers substantial applications in the production of hydrogen but requires an inexpensive catalyst. Herein, silica (SP) and phosphorylated silica (SP-PA) are used as a catalyst for the generation of hydrogen from NaBH4 hydrolysis. The catalyst is prepared by sol-gel route synthesis by taking tetraethyl orthosilicate as the precursor of silica whereas phosphoric acid served as the gelation and phosphorylating agent. The prepared catalyst is characterized by FT-IR spectroscopy, XRD, SEM, and EDAX. The hydrogen generation rate at SP-PA particles (762.4mLmin-1g-1) is higher than that of silica particles (133mLmin-1g-1 of catalyst). The higher catalytic activity of SP-PA particles might be due to the acidic functionalities that enhance the hydrogen production rate. The kinetic parameters(activation energy and pre-exponential factor) are calculated from the Arrhenius plot and the thermodynamic parameters (enthalpy, entropy, and free energy change) are evaluated using the Erying plot. The calculated activation energy for NaBH4hydrolysis at SP-PA catalyst is 29.92kJ.mol-1 suggesting the high catalytic activity of SP-PA particles. The obtained entropy of activation (ΔS‡ = - 97.75 JK-1) suggested the Langmuir-Hinshelwood type associative mechanism for the hydrolysis of NaBH4at SP-PA particles.

Photo-thermal synergic enhancement of CoxFeAl-LDHs for hydrogen generation from hydrolysis of NaBH4

The production of hydrogen from sodium borohydride (NaBH4) with a suitable catalyst is a promising route for the hydrogen industry. The exploration of the energy-saving catalysts with visible light response and photothermal effect is necessary for utilizing solar energy in hydrogen utilization from hydrolysis of NaBH4. In this study, a series of photo-thermal catalysts of CoxFeAl layered double hydroxides (CoxFeAl-LDHs x = 4, 6, 8) with abundant oxygen vacancy (Vo) are successfully synthesized for photo-thermal synergic catalytic H2 generation from hydrolysis of NaBH4. CoxFeAl-LDHs differ in bandgap, Vo concentration, and photo-thermal performance, with Co6FeAl-LDH show the highest concentration of Vo and most efficient photo-thermal performance under 400–700 nm irradiation. Co6FeAl-LDH can significantly lower the activation energy of the hydrolysis of NaBH4 (Ea = 35.46 kJ mol−1) and demonstrates excellent photo-thermal synergic performance with H2 generation rate of 3.38 mol g−1 h−1 without additional heat source. The mechanism study shows that the h+, ∙OH, and Vo in CoxFeAl-LDHs also play essential roles in the hydrolysis of NaBH4. This work develops a hydrotalcite-based photo-thermal synergistic catalyst, which provides a new approach for the design of sodium borohydride hydrolysis catalysts for hydrogen production.

Hydrogen generation of single alloy Pd/Pt quantum dots over Co3O4 nanoparticles via the hydrolysis of sodium borohydride at room temperature

To satisfy global energy demands and decrease the level of atmospheric greenhouse gases, alternative clean energy sources are required. Hydrogen is one of the most promising clean energy sources due to its high chemical energy density and near-zero greenhouse gas emissions. A single alloyed phase of Pd/Pt nanoclusters as quantum dots (QDs) was prepared and loaded over Co3O4 nanoparticles with a low loading percentage (1 wt.%) for hydrogen generation from the hydrolysis of NaBH4 at room temperature. L-glutathione (SG) was used as a capping ligand. It was found that the single alloy catalyst (Pd0.5–Pt0.5)n(SG)m/Co3O4 caused a significant enhancement in hydrogen generation in comparison to the monometallic clusters (Pdn(SG)m and Ptn(SG)m). Moreover, the Pd/Pt alloy showed a positive synergistic effect compared to the physical mixture of Pd and Pt clusters (1:1) over Co3O4. The QDs alloy and monometallic Pd and Pt clusters exhibited well-dispersed particle size in ~ 1 nm. The (Pd0.5–Pt0.5)n(SG)m)/Co3O4 catalyst offers a high hydrogen generation rate (HGR) of 8333 mL min− 1 g− 1 at room temperature. The synergistic effect of Pd and Pt atoms in the nanoclusters alloy is the key point beyond this high activity, plus the prepared clusters' unique atomic packing structure and electronic properties. The effect of the NaBH4 concentration, catalyst amount, and reaction temperature (25–60 °C) were investigated, where HGR reaches 50 L min− 1 g− 1 at 60 °C under the same reaction conditions. The prepared catalysts were analyzed by UV–Vis, TGA, HR-TEM, XRD, and N2 adsorption/desorption techniques. The charge state of the Pd and Pt in monometallic and alloy nanoclusters is zero, as confirmed by X-ray photoelectron spectroscopy analysis. The catalysts showed high recyclability efficiency for at least five cycles due to the high leaching resistance of the alloy nanoclusters within the Co3O4 host. The prepared catalysts are highly efficient for energy-based applications.

Zn-MOF-74-derived graphene nanosheets supporting CoB alloys for promoting hydrolytic dehydrogenation of sodium borohydride

The development of an efficient tactic for enhancing the catalytic activity toward hydrolytic dehydrogenation of sodium borohydride (NaBH4) is of vital significance but remains a long-standing challenge. In this work, CoB alloys were successfully anchored on MOF-74-derived graphene nanosheets (GNS) via the chemical reduction process. As a catalyst support, GNS can provide a high dispersion of CoB alloys to expose more active sites. Moreover, the existence of a synergistic effect between CoB alloys and GNS is verified by a series of well-designed control experiments. Therefore, a low activation energy (Ea = 38.8 kJ·mol–1) and a high hydrogen generation rate (HGR = 7937 mlH2·min−1·g−1) are simultaneously achieved for the optimized Co1B/GNS catalyst. In addition, Co1B/GNS has decent recyclability, i.e., 58 % of the initial HGR remaining after ten successive cycles of NaBH4 hydrolysis. This work provides a feasible approach for fabricating high-performance non-noble metal catalysts for hydrolytic dehydrogenation of NaBH4.

Effect of hydroxyl (·OH) radicals on the progression of NaBH4 hydrolysis reaction on fcc-Co surfaces: A DFT study

The effect of ·OH radical in the medium for the sodium borohydride (NaBH4) hydrolysis reaction in presence of face-centered cubic (fcc) Cobalt (Co) catalyst was investigated based on density functional theory (DFT). The main purpose is to determine the effective cobalt surface for the disassociation of hydrogen from NaBH4, and the catalyst performance for the intermediate steps formed by the decomposition of water on the cobalt surface. Low index fcc-Co catalyst surfaces were used for the catalyzed NaBH4 hydrolysis reaction. As a result of the calculations, Co(111) is the most effective surface among the low index fcc-Co surfaces for the hydrolysis reaction. Therefore, the possible steps of the NaBH4 hydrolysis reaction are modeled on the Co(111) surface for ambient conditions containing different concentrations of H* atoms, ·OH* radicals, and H2O* molecules. According to our results, the concentration of ·OH* radicals adsorbed on the surface is directly proportional to the change in activation energy. In addition, calculations for the possible second and third steps of the hydrolysis reaction showed that the steps involving NaBH3OH and NaBH3O base molecular structures, respectively, are more feasible than others. This will be a guide for experimental studies in terms of time and cost.

Palladium mesoporous nanoparticles Pd NPs@[KIT-6] and Pd NPs@[KIT-6]-PEG-imid as efficient heterogeneous catalysts for H2 production from NaBH4 hydrolysis

• Pd NPs supported ordered mesoporous were synthesized. • Pd NPs were characterized by XPS, XRD, TEM, SEM, FT-IR and NMR spectroscopy. • Catalyst loading, temperature, NaOH and NaBH 4 concentration effects were examined. • Pd NPs catalyze the hydrolytic production of H 2 from NaBH 4 with TOF of 176 mole H2 .mol cat −1 .min −1 . • Pd NPs catalyst retains 71.6% of its initial catalytic activity after five cycles. The ordered mesoporous silica supported Pd NPs, denoted as Pd NPs@[KIT-6] 2 and Pd NPs@[KIT-6]-PEG-imid 6 , were synthesized by a deposition precipitation method using the [KIT-6] 1 or [KIT-6]-PEG-imid 5 , respectively, and Na 2 PdCl 4 followed by in situ reduction by NaBH 4 . The obtained supported Pd NPs 2 and 6 were fully characterized by XPS, XRD, TEM, SEM, FT-IR and solid-state 29 Si and 13 C NMR spectroscopy. The effect of several parameters such as catalyst loading, temperature, NaOH and NaBH 4 concentration were examined to obtain the optimum reaction conditions. The supported Pd NPs 2 and 6 catalyze the hydrolytic production of H 2 from NaBH 4 with notable efficiencies and the catalyst stabilized by PEG and imidazolium ionic liquid based-[KIT-6] 6 is more active than its [KIT-6] counterpart 2 . A TOF of 176 mole H2 .mol cat −1 .min −1 for 6 was achieved when the reaction was performed with a low catalyst loading of 0.1 mol%. Reaction kinetics studies showed that the hydrolysis is first order in catalyst and NaBH 4 with apparent E a of 35.0 and 35.7 kJ mol −1 for 2 and 6 , respectively. The efficiency of catalyst 6 for the hydrolysis of NaBH 4 was investigated in H 2 O and D 2 O and indicated that the reaction is considerably faster in H 2 O than in D 2 O with primary KIE k H /k D = 2.36. In addition, the PdNPs based [KIT-6] mesoporous silica 6 retains 71.6% of its initial efficiency after five cycles.

Review on Magnesium Hydride and Sodium Borohydride Hydrolysis for Hydrogen Production

Metal hydrides such as MgH2 and NaBH4 are among the materials for with the highest potential solid-state hydrogen storage. However, unlike gas and liquid storage, a dehydrogenation process has to be done prior to hydrogen utilization. In this context, the hydrolysis method is one of the possible methods to extract or generate hydrogen from the materials. However, problems like the MgH2 passivation layer, high cost and sluggish self-hydrolysis of NaBH4 are the known limiting factors for this process, but they can be overcome with the help of catalysts. In this works, selected studies have been reviewed on the performance of catalysts like chloride, oxide, fluoride, platinum, ruthenium, cobalt and nickel-based on the MgH2 and NaBH4 system. These studies show a significant enhancement in the amount of hydrogen released as compared to the hydrolysis of the pure MgH2 and NaBH4. Therefore, the addition of catalysts is proven as one of the options in improving hydrogen generation via the hydrolysis of MgH2 and NaBH4.

Metal boride-decorated CoNi layered double hydroxides supported on muti-walled carbon nanotubes as efficient hydrolysis catalysts for sodium borohydride

Without effective and secure hydrogen production, it is impossible to utilize hydrogen energy on a large scale. Whereas hydrogen emission from NaBH4 hydrolysis with high hydrogen yield is an impressively efficient hydrogen supply method. However, it is affected by sluggish hydrogen production kinetics and low yields, therefore it is required to develop hydrolysis catalysts with good performance under alkaline conditions. In this study, a composite of unique CoNi layered double hydroxide (CoNi-LDH) nanosheets interconnected by muti-walled carbon nanotubes (MWCNTs) was prepared for the first time, and the surface was modified with metal borides produced by in-situ reduction. Among them, CoNi-LDH nanosheets are created when CoNi-MOF spontaneously derivates in alkaline electrolytes. The successful preparation of CoB-LDH-CNT has been confirmed by SEM, TEM, EDS, XRD, and XPS characterization. The hydrolysis experiments show that it has good catalytic activity with an optimal hydrogen generation rate (HGR) of 5167.72 mL·min−1·g−1 and low activation energy (Ea) of 29.93 kJ·mol−1. After ten cycles of experiments, it still has 75.4% of the initial performance, showing excellent stability, which may be attributed to the fact that MWCNTs can help to reconnect broken nanosheets during the reaction. This interconnected multistage structure offers a new methodology for enhancing the catalytic performance of metal boride and metal hydroxide materials.

Low-cost and reusable iron- and nickel-based metal boride nanoparticles for efficient catalytic hydrolysis of sodium borohydride

Development of efficient catalysts for hydrogen evolution reaction is of key importance for the safe storage and utilization of hydrogen from the hydrolysis of NaBH4. In this study, a series of nanocatalysts containing iron- and nickel-based metal borides were developed through a mechanochemical route followed by a wet milling step. The use of the mole ratio of metal chlorides to NaBH4 as 1:2 enabled the simultaneous formation of Ni3B and FeB phases, while the room-temperature synthesis method caused a uniform morphology with an average particle size and surface are of 70 nm and 41.8 m2/g, respectively. This powder showed the best catalytic performance compared to other samples with a hydrogen generation rate value of 758 ml H2 min−1 gcat−1 at room temperature and an activation energy of 40.8 kJ/mol. The catalyst performed good durability for each cycle and retained about 70% of its initial catalytic activity after 5 cycles. The availability of active iron, nickel, and boron species on the surface contributed to the enhancement of catalytic activity. As-prepared catalysts can be considered as low-cost and reusable materials for the efficient hydrolysis of sodium borohydride.

Oxygen-vacancy-rich Ru-clusters decorated Co/Ce oxides modifying ZIF-67 nanocubes as a high-efficient catalyst for NaBH4 hydrolysis

Designing a cost-effective and high-performance catalyst for NaBH4 hydrolysis is a significant step in developing a sustainable hydrogen source. Herein, we prepared a cost-effective Ru-clusters decorated cobalt-cerium oxides coating ZIF-67 (Ru/Co6Ce1@ZIF-67) catalyst via a facile reduction method, displaying high performance and exceptional reusability in alkaline NaBH4 solution. The optimized catalyst exhibits a high hydrogen generation rate (HGR, 5726.1 mL min−1 g−1), turnover frequency (TOF, 413.9 molH2 min−1molRu−1), and low activation energy (Ea, 53.0 kJ mol−1), surpassing most of the recently reported catalysts. Furthermore, the catalytic performance does not change considerably after five cycles, indicating the catalyst's multi-cycle reusability. Studies imply the uniquely synergistic effect of Ru, Co/Ce oxides, abundant oxygen vacancies, as well as the porous nanocube structure, enabling the catalysts to possess high metal dispersion, outstanding catalytic performance and exceptional reusability. This work will open light on using an oxygen vacancies-rich strategy to design a high-activity catalyst for promoting NaBH4 hydrolysis.

Effects of various metal doping on the structure and catalytic activity of CoB catalyst in hydrogen production from NaBH4 hydrolysis

Four ternary alloy CoB-based catalysts, including Co-Sn-B, Co-Mn-B, Co-Cr-B and Co-Bi-B, were prepared by chemical reduction method.The effect of Sn, Mn, Cr and Bi dopants on phase structure, surface morphologies, electronic interaction, catalytic activity and activation energies of CoB catalysts investigated in depth. Their catalytic activity in hydrogen production from NaBH4 hydrolysis was compared systematically. Compared with undoped CoB catalyst, it can be found that the doping of Cr and Bi exhibits a significant promoting effect on CoB catalyst by accelerating hydrogen generation rate. Nevertheless, the introduction of Sn and Mn into CoB catalyst only attains a slight increase in hydrogen production rate. The doping concentration of Sn, Mn, Cr, Bi species in CoB was adjusted to respectively check their phase structure and catalytic performance, indicating that there is an optimum doping concentration for each dopant. It can be concluded that the promoting effect of various dopants on catalytic performance can be attributed to crystalline phase, specific surface area and electronic interaction involved in NaBH4 hydrolysis.

Graphene-Modified Co-B-P Catalysts for Hydrogen Generation from Sodium Borohydride Hydrolysis.

Sodium borohydride (NaBH4) is considered a good candidate for hydrogen generation from hydrolysis because of its high hydrogen storage capacity (10.8 wt%) and environmentally friendly hydrolysis products. However, due to its sluggish hydrogen generation (HG) rate in the water, it usually needs an efficient catalyst to enhance the HG rate. In this work, graphene oxide (GO)-modified Co-B-P catalysts were obtained using a chemical in situ reduction method. The structure and composition of the as-prepared catalysts were characterized, and the catalytic performance for NaBH4 hydrolysis was measured as well. The results show that the as-prepared catalyst with a GO content of 75 mg (Co-B-P/75rGO) exhibited an optimal catalytic efficiency with an HG rate of 12087.8 mL min−1 g−1 at 25 °C, far better than majority of the findings that have been reported. The catalyst had a good stability with 88.9% of the initial catalytic efficiency following 10 cycles. In addition, Co-, B-, and P-modified graphene showed a synergistic effect improving the kinetics and thermodynamics of NaBH4 hydrolysis with a lower activation energy of 28.64 kJ mol−1. These results reveal that the GO-modified Co-B-P catalyst has good potential for borohydride hydrolysis applications.

Synthesis of “needle-cluster” NiCo2O4 carbon nanofibers and loading of Co-B nanoparticles for hydrogen production through the hydrolysis of NaBH4

Hydrogen production through chemical processes has received considerable attention. Replacing precious-metal-based catalysts in NaBH4 hydrolysis entails challenges such as the low durability and efficiency of non-precious metals. Here, carbon nanofiber (CNF)-supported NiCo2O4 and CoB were synthesized to form a burr-shaped rod-like catalyst (CNF-NiCo2O4-CoB). The morphology and microstructure of the catalyst were characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller adsorption analysis. Then, NaBH4 hydrolysis was catalyzed using CNF-NiCo2O4-CoB. At 303 K, the hydrogen production rate and activation energy of the hydrolysis reaction were 5225 mL min−1 g−1 and 38.32 kJ mol−1, respectively. The maximum hydrogen production rate achieved using this composite catalyst was significantly higher than that of a pure CoB catalyst. The composite catalyst also exhibited high durability, maintaining 82.5% of its initial catalytic activity even after nine hydrolysis cycles. The magnetic nature of the catalyst improved its recyclability. This work provides a new method for synthesizing composite-structured catalysts, exhibiting considerable potential in the hydrolysis of NaBH4.