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The exploitation of economical and high‐efficient heterogeneous catalysts plays a vital role in ammonia‐borane (NH3BH3, AB) hydrolysis for hydrogen evolution. Herein, poly(N‐vinyl‐2‐pyrrolidone) (PVP) stabilized highly dispersed Ru–Ni nanoclusters immobilized on reduced graphene oxide (rGO) are successfully synthesized via in situ chemical reduction. The optimized Ru1Ni1@PVP/rGO‐1 catalyst exhibits a superior catalytic performance toward hydrolytic dehydrogenation of AB for hydrogen evolution, with a low activation energy (Ea) of 21.1 kJ mol−1 and a high turnover frequency (TOF) value of 425.1 molH2 molRu−1 min−1at 298 K. Moreover, an outstanding recyclability with 82.1% of the initial catalytic activity is achieved after 20 consecutive cycles due to PVP coating that can effectively prevent the agglomeration of nanoclusters during the recycling tests. Experimental analyses and DFT calculations reveal a synergistic effect in Ru–Ni nanoclusters, resulting in a strong adsorption of AB molecules and an easy activation of water molecules on Ru–Ni nanoclusters. These findings in this study open a new avenue for a hopeful design of highly efficient heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Sodium borohydride (NaBH4), with a high theoretical hydrogen content (10.8 wt%) and safe characteristics, has been widely employed to produce hydrogen based on hydrolysis reactions. In this work, a porous titanium oxide cage (PTOC) has been synthesized by a one-step hydrothermal method using NH2-MIL-125 as the template and L-alanine as the coordination agent. Due to the evenly distributed PtNi alloy particles with more catalytically active sites, and the synergistic effect between the PTOC and PtNi alloy particles, the PtNi/PTOC catalyst presents a high hydrogen generation rate (10,164.3 mL∙min−1∙g−1) and low activation energy (28.7 kJ∙mol−1). Furthermore, the robust porous structure of PTOC effectively suppresses the agglomeration issue; thus, the PtNi/PTOC catalyst retains 87.8% of the initial catalytic activity after eight cycles. These results indicate that the PtNi/PTOC catalyst has broad applications for the hydrolysis of borohydride. [ABSTRACT FROM AUTHOR]

Without effective and secure hydrogen production, it is impossible to utilize hydrogen energy on a large scale. Whereas hydrogen emission from NaBH 4 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 (E a) 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. • Novel CoB-LDH-CNT compositions was prepared for hydrogen production of NaBH 4 hydrolysis for the first time. • CoB-LDH-CNT-50 achieves good HER performance and the lowest E a of 29.93 kJ∙mol−1. • The bonding effect of multi-walled carbon nanotubes (MWCNTs) enabled the catalyst to maintain 75.4% activity after 10 cycles. [ABSTRACT FROM AUTHOR]

As a promising hydrogen storage material, sodium borohydride (NaBH4) exhibits superior stability in alkaline solutions and delivers 10.8 wt.% theoretical hydrogen storage capacity. Nevertheless, its hydrolysis reaction at room temperature must be activated and accelerated by adding an effective catalyst. In this study, we synthesize Co nanoparticles supported on bagasse-derived porous carbon (Co@xPC) for catalytic hydrolytic dehydrogenation of NaBH4. According to the experimental results, Co nanoparticles with uniform particle size and high dispersion are successfully supported on porous carbon to achieve a Co@150PC catalyst. It exhibits particularly high activity of hydrogen generation with the optimal hydrogen production rate of 11086.4 mLH2∙min−1∙gCo−1 and low activation energy (Ea) of 31.25 kJ mol−1. The calculation results based on density functional theory (DFT) indicate that the Co@xPC structure is conducive to the dissociation of [BH4]−, which effectively enhances the hydrolysis efficiency of NaBH4. Moreover, Co@150PC presents an excellent durability, retaining 72.0% of the initial catalyst activity after 15 cycling tests. Moreover, we also explored the degradation mechanism of catalyst performance. [ABSTRACT FROM AUTHOR]

Monolithic catalyst is very important for the further industrial application of hydrogen production via NaBH 4 hydrolysis. Nowadays, the structural stability and catalytic performance of aerogel based monolithic catalysts still need to be further improved. Herein, the amorphous Ru–Co(OH) x @GO particles are synthesized by in-situ growth and transformation of ZIF-67 on the surface of GO, the hydrogen generation rate and activation energy via catalytic NaBH 4 hydrolysis can reach 11,062 mL min−1 g−1 and 36.2 kJ mol−1, respectively. Meanwhile, the composite aerogel of Ru–Co(OH) x @GO, chitosan and carbonylated cellulose nanofiber is prepared by solution blending and freeze drying, and the hydrogen generation rate has 7680 mL min−1 g−1 (retained 69.4%) under the same amount of Ru–Co(OH) x @GO. Furthermore, after high speed catalytic hydrogen generation, the aerogel can still maintain its structural integrity, thus facilitating recovery and reuse, which is attributed to the co-structural coupling of carbonylated cellulose nanofiber and chitosan macromolecule to the skeleton. This work provides a convenient and controllable strategy for the development of monolithic catalysts. • ZIF-67 nanocrystalline was in-situ grown on GO. • Amorphous RuCo(OH) x was transformed by etching. • Composite aerogel displayed lamellar skeleton and porous channel. • The hydrogen generation rate of the aerogel had 7680 mL min−1 g−1. • The aerogel had a complete structure after catalytic hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] Commercial carriers have been used to prepare monolithic NaBH 4 hydrolytic catalysts, but the fixed structure and material limit the application scope and design freedom. Herein, the RuO 2 -CoP catalyst is coated on the surface of fibrous sepiolite (RuO 2 -CoP@aSep) by in-situ deposition, annealing in air and phosphating, which is constructed into the aerogel with cellulose nanofiber (CNF) and polyvinyl alcohol (PVA) by freeze drying process. The hydrogen generation rate (HGR) of RuO 2 -CoP@aSep increases from 3655 to 10713 m L m i n - 1 g c a t a l y s t - 1 by adjusting the mass ratio of cobalt to ruthenium in RuO 2 -CoP. Moreover, the optimized composite aerogel can get HGR (5268 m L m i n - 1 g c a t a l y s t - 1 ) by regulating its formulation, and the catalytic activity and mass loss rate of the aerogel maintains 76.6 and 0.92 % after five cycles of testing. The synergistic interaction between Ru and Co species, micro-nano porous structure, and structural coupling provide good catalytic activity and cycling performance, and show great potential in the design of controllable NaBH 4 hydrolyzed monolithic catalysts. [ABSTRACT FROM AUTHOR]

Rapid release of hydrogen at ambient condition is highly favorable and is necessary for fuel cell power generation on-demand. Hydrolysis of hydrides offers such advantage with sodium borohydride (NaBH 4) as a representative exemplar. Despite with exceptionally high hydrogen content, the hydrolysis kinetics of NaBH 4 is sluggish in the absence of catalyst. Co–B alloy has generally been employed as effective catalyst in the hydrolysis of borohydrides. However, Co–B particles are prone to agglomeration during the reaction, reducing the activity and durability of the catalyst. In this work, waxberry-like hierarchical porous carbon microspheres (HPCMs) were successfully prepared and were used as carriers to support Co–B particles to form the Co–B/HPCMs catalyst. The effects of HPCMs with different nitrogen contents in Co–B/HPCMs on the catalytic dehydrogenation rate of NaBH 4 hydrolysis were systematically investigated. The experimental results showed that Co–B/HPCM-2 exhibited excellent catalytic activity in the hydrolysis of NaBH 4 at 298 K, with a low activation energy of 43.3 kJ ·mol−1 and a high hydrogen generation rate of 3083.1 ml H2 ·min−1·g−1. Moreover, after five consecutive cycles, its catalytic activity maintained at 91.7 % of the initial catalytic activity, displaying satisfactory cycling performance. The findings obtained from this study are expected to expand a novel path for the development of efficient Co-based catalysts in heterogeneous catalytic reactions. • The Co–B/HPCM catalysts were successfully prepared. • Co–B/HPCM exhibited superior catalytic activity toward NaBH 4 hydrolysis. • A low E a of 43.3 kJ ·mol−1 and a high HGR of 3083.1 ml H2 ·min−1·g−1 were achieved. [ABSTRACT FROM AUTHOR]

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH 3 BH 3 ; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co 2 P) via phosphatization to form Co 2 P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H 2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 mol H2 ·mol Ru −1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB. • The Ru/NCP-CNT catalysts were successfully prepared. • Ru/NCP-CNT exhibited superior catalytic activity toward AB hydrolysis. • Low E a of 32.4 kJ·mol−1 and high TOF of 193.9 mol H2 ·mol Ru −1·min−1 were achieved. • Synergistic effect between Ru NPs and NCP-CNT was responsible for the improved performance. [ABSTRACT FROM AUTHOR]

The fast release of hydrogen from borohydride is highly desired for a fuel cell system. However, the generation of hydrogen from borohydride is limited by the low activity and low stability of the catalyst. Herein, a highly active catalyst is synthesized through a simple one-step chemical reduction using bacterial cellulose (BC) derived carbon as a support for the active Co–B alloy. The morphology and microstructure of the BC/Co–B nanocomposite are characterized by SEM, TEM, XRD, and BET adsorption analysis. The BC/Co–B possesses high surface area (125.31 m2 g−1) high stability and excellent catalytic activity for the hydrolysis of NaBH 4. Compared with unsupported Co–B nanocomposite or commercial carbon supported Co–B, the BC/Co–B nanocomposite shows greatly improved catalytic activity for the hydrolysis of NaBH 4 with a high hydrogen generation rate of 3887.1 mL min−1 g−1 at 30 °C. An activation energy of 56.37 kJ mol−1 was achieved for the hydrolysis reaction. Furthermore, the BC/Co–B demonstrated excellent stability. These results indicate that the BC/Co–B nanocomposite is a promising candidate for the hydrolysis of borohydrides. • Co–B was high dispersed on bacterial cellulose derived carbon. • A hydrogen generation rate of 3887.1 mL min−1 g−1 was achieved at 30 °C for the hydrolysis of NaBH 4. • Co–B on the carbon support showed significantly enhanced catalytic activity. • BC/Co–B nanocomposite shows good stability. [ABSTRACT FROM AUTHOR]

In this work, poly(N -vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles (NPs) supported on bamboo leaf-derived porous carbon (Ru/BC) has been synthesized via a one-step procedure. The structure and morphology of the as-synthesized samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). As a catalyst for hydrogen generation from the hydrolysis of ammonia-borane (AB, NH 3 BH 3) at room temperature, Ru/BC stabilized with 1 mg of PVP exhibited high activity (TOF = 718 mol H2 ·mol Ru −1·min−1) and low activation energy (E a = 22.8 kJ mol−1). In addition, the catalyst could be easily recovered and showed fairly good recyclability with 55.6% of the initial catalytic activity retained after ten experimental cycles, which confirmed that PVP could stabilize the Ru NPs and prevent their agglomeration on BC surface. Our results suggest that PVP-stabilized Ru/BC is a highly efficient catalyst for the hydrolysis of AB. • Ru nanoparticles are successfully supported on porous carbon (Ru/BC). • PVP-stabilized Ru/BC catalyst can efficiently catalyze AB hydrolysis. • Ru/BC-1 exhibits high activity with E a of 22.8 kJ mol−1 and TOF of 718 molH 2 ·mol Ru −1·min−1. • Ru/BC-1 can be easily recovered and exhibits fairly good recyclability. [ABSTRACT FROM AUTHOR]

Abstract In this paper, ruthenium supported on nitrogen-doped porous carbon (Ru/NPC) catalyst is synthesized by a simple method of in situ reduction using ammonia borane (AB) as reducing agent. The composition and structure of Ru/NPC catalyst are systematically characterized. This catalyst can efficiently catalyze the hydrolysis of AB. The hydrogen production reaction is completed within about 90 s at a temperature of 298 K and the maximum rate of hydrogen production is 3276 ml·s−1·g−1 with a reduced activation energy of 24.95 kJ·mol−1. The turnover frequency (TOF) for hydrogen production is about 813 mol H2 ·mol Ru −1·min−1. Moreover, this catalyst can be recycled with a well-maintained performance. After five cycles, the maximum rate of hydrogen generation is maintained at 2206 ml·s−1·g−1, corresponding to 67.3% of the initial catalytic activity. Our results suggest that Ru/NPC prepared by in situ reduction is a highly efficient catalyst for hydrolytic dehydrogenation of AB. Highlights • Ru/NPC catalyst is successfully prepared by in situ reduction. • Ru/NPC catalyst can efficiently catalyze AB hydrolysis. • The rate of H 2 production is 3276 ml·s−1·g−1 with E a of 24.95 kJ·mol−1 and TOF of 813 molH 2 ·mol Ru −1·min−1. [ABSTRACT FROM AUTHOR]

Highly dispersed Co–Ce–B nanoparticles supported on chitosan-derived carbon (Co–Ce–B/Chi–C) were synthesized through chemical reduction and carbonization. The morphology and microstructure of the Co–Ce–B/Chi–C nanocomposite were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller adsorption analysis. This nanocomposite had uniform morphology and large surface area, and it showed high catalytic activity for NaBH 4 hydrolysis and good cycle stability. Compared with unsupported Co–Ce–B particles, this nanocomposite showed greatly increased catalytic activity for NaBH 4 hydrolysis. A remarkably high hydrogen generation rate of 4760 mL −1 min −1 g −1 at 30 °C was achieved with low activation energy of 33.1 kJ mol −1 . These results indicate that the Co–Ce–B/Chi–C nanocomposite is a promising catalyst for on-demand hydrogen generation via NaBH 4 hydrolysis. [ABSTRACT FROM AUTHOR]

Powder type catalysts aren't often easily recycled after use and resulted in water pollution for hydrogen production by NaBH 4 hydrolysis. Based on this, Ru-CoP is firstly anchored on the surface of graphene oxide (GO) by in-situ growth of ZIF-67, water etching, phosphating and loading Ru, then a novel composite aerogel-type catalyst is fabricated with chitosan (CS), GO and Ru-CoP@GO by the facile freeze-drying method. The results show that the hydrogen generation rate (HGR) of Ru-CoP@GO is 7200 mL min − 1 g catalyst − 1 , and the activation energy is 47.7 kJ mol−1, which is not only the sheet catalyst with high catalytic performance, but also the excellent filler for composite aerogel, attributed to the strong interaction between Ru and Co species. Meanwhile, by regulating the amounts of CS, GO and Ru-CoP@GO, the loss rate of Ru-CoP@GO/CS aerogel is only 23% at the hydrogen generation rate (4712 mL min − 1 g catalyst − 1 ) after five cycles of catalytic testing, which is due to structural coupling action and the formation of amide bond between Ru-CoP@GO, CS and GO, demonstrating an excellent structural stability. This work provides a precise and controllable strategy for the development of monolithic catalysts. • The aerogel of Ru-CoP@GO/CS was used to catalyze NaBH 4 hydrolysis. • The Ru-CoP catalyst was in-situ loaded on the GO surface. • The sheeted Ru-CoP@GO was assembled into aerogel with CS and GO by freeze-drying. • Its excellent performances of the aerogel were due to the structural coupling and amide bond between different components. [ABSTRACT FROM AUTHOR]

Sodium borohydride (NaBH 4) has been widely regarded as the one of most promising future hydrogen (H 2)-generated materials. Therefore, it is necessary to find a catalyst with higher catalytic performance to promote the on-demand H 2 release of NaBH 4 hydrolysis. In this study, a Ru@CoAl-LDH catalyst was developed by immobilizing Ru nanoparticles (Ru NPs) on the surface of Co Al Layered Double Hydroxide (CoAl-LDH) nanocurds. The Ru NPs were prepared by H 2 reduction, and nanoflower-like CoAl-LDH was synthesized through a one-step solvothermal method. The microstructure and composition of the catalysts were investigated through scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that Ru@CoAl-LDH exhibited good catalytic performance toward the NaBH 4 hydrolysis. At 30 °C, the hydrogen generation rate of the hydrolysis reaction was 44.34 L·min−1·g Ru −1, and the reaction activation energy was 38.83 kJ·mol−1, and superior to many catalysts of the same type. Because of its high activity, low activation energy and excellent economic performance, this catalyst has high potential for applications in NaBH 4 hydrolysis. • Nanoflower-like Ru@CoAl-LDH synthesized via solvothermal & hydrogen reduction. • The catalyst is cost-effective with 0.22 wt% Ru. • The catalyst exhibited high HG rate, high stability, and low activation energy. • Ru@CoAl-LDH is a promising catalyst for NaBH 4 hydrolysis. [ABSTRACT FROM AUTHOR]

NaBH 4 (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 NaBH 4 hydrolysis reaction. The hydrogen generation rate (HGR) is as high as 9815.82 mL H2 min−1 g−1, and the activation energy (E a) 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. • A method of double protection of internal & external structures is proposed to improve the performance of catalysts. • The stability & reusability of H-Co/N/C-Ru@C-650 were enhanced by carbonizing ZIF-67 as the framework and coating. • H-Co/N/C-Ru@C-650 exhibited excellent activity on NaBH 4 with a H 2 generation rate of 9815.82 mL H2 min−1 g−1. • H-Co/N/C-Ru@C-650 still retained 81.3% of its initial catalytic activity after 25 runs. [ABSTRACT FROM AUTHOR]

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. Co 0.25 Ni 0.75 B@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 Co 0.25 Ni 0.75 B@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, Co 0.75 Ni 0.25 B@CNTs was used as catalyst with excellent catalytic activity for the hydrolysis of NaBH 4 , with hydrogen production rates of 6245.75 mL min−1 g catalyst −1 and 18135.16 mL min−1 g Co,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 NaBH 4 hydrolysis. This work has a good inspiration for the development of bifunctional composite materials in the future. [Display omitted] • Homogeneous Co-Ni-B particles were reduced in situ on carboxylated CNTs with the assistance of TEA. • The synergistic effect of Co and Ni increased the exposure of CoNiB@ca-CNTs active sites. • The specific capacitance of the supercapacitor is 2078 F g−1 at 1 A g−1. • The asymmetric supercapacitor exhibit a high energy density of 67.4 Wh kg−1 at 400.4 W kg−1. • The catalyst achieved good HGR performance and the lowest Ea of 28.67 kJ∙mol−1. [ABSTRACT FROM AUTHOR]

In this work, amorphous Co-Cr-B/NG catalysts were prepared by the chemical reduction method. A descriptor of "valence band center" was introduced to the NaBH 4 hydrolysis reaction to investigate the relationship between the valence band and the catalytic activity of amorphous Co-Cr-B/NG catalysts. The outcomes show that the valence band center of the Co-Cr-B/NG hybrids has been significantly changed after the Cr content is regulated by the preparation process, which can facilitate the modulation of the electronic structure of the catalysts. The hydrogen release rate shows a shape of a volcano with the valence band center. The hydrolysis performance test results of the optimum catalyst demonstrated that the hydrogen release rate of NaBH 4 water at 25 °C was 2231.7 mL·min−1·g−1 with an activation energy of 38.41 KJ·mol−1, according to the volcano curve. • Adjustment of the material ratio by the preparation process regulates the valence band. • The relationship between the catalytic performance of the catalyst and V d -E f. • The activation energy of Co-Cr-B/NG at 25 °C is 38.41 KJ·mol−1. [ABSTRACT FROM AUTHOR]

Developing high-performance hydrogen generation/storage materials and technologies is an essential step for applying hydrogen-oxygen fuel cells under the background of carbon peak and carbon neutralization strategy. Ammonia borane (NH 3 BH 3 , AB) features a high volumetric and gravimetric density of hydrogen, showing great potential for chemical hydrogen storage. Exploring low-cost and high-efficiency catalysts is an essential prerequisite for hydrogen generation through AB hydrolysis under mild conditions. Herein, with rationally designing Ru/Co metal-organic framework (RuCo-MOF), a series of Co 2 P nanoparticles doping with low-content Ru embedded in nitrogen-doped carbon supported on graphene oxide (Ru-Co 2 P@N-C/GO) were synthesized via a one-pot phosphorization process. Benefiting from the unique structure and the electronic structure regulation of Ru, Ru-Co 2 P@N-C/GO exhibits excellent catalytic performance with an original turnover frequency (TOF) of 347.3 mol H2 mol Ru –1 min–1 and an excellent specific rate (r B) of 83,929 mL min–1 g Ru –1 toward AB hydrolysis. This work opens a new avenue toward developing effective and economic catalysts for AB hydrolysis. • Ru-Co 2 P@N-C/GO with low Ru content is prepared through a one-pot phosphorization process. • Unique structure and electronic structure regulation are observed for Ru-Co 2 P@N-C/GO. • Superior catalytic activity with TOF of 347.3 mol H2 mol Ru −1 min−1 is achieved for AB hydrolysis. [ABSTRACT FROM AUTHOR]

A cobalt–boron/nickel–boron (Co–B/Ni–B) nanocomposite was synthesized in a two-step process by in situ reduction of nickel and cobalt salts. Characterization of the nanocomposite using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller adsorption analysis showed that the Co–B nanoparticles were well dispersed on the Ni–B surface. Enlisted as a catalyst in the hydrolysis of ammonia borane (AB) for hydrogen generation (HG), the nanocomposite exhibited better catalytic activity than Co–B and Ni–B at room temperature; the HG rate was 1368.2 mL min −1 g −1 at 25 °C in a 1.5 wt.% AB solution, with a low activation energy of 33.5 kJ mol −1 . The effect of the complexing agent (sodium citrate) on the nanocomposite's catalytic activity was also investigated. In addition, recycling tests showed that Co–B/Ni–B was still highly active and preserved 84% of its initial catalytic activity after 11 recover-and-reuse cycles. [ABSTRACT FROM AUTHOR]

A Co–Zn–B/graphene nanocomposite was prepared by in situ reduction of cobalt and zinc salts on the surface of graphene (GP), and its catalytic performance in hydrogen generation (HG) by hydrolysis of NaBH 4 was investigated. This composite exhibited excellent catalytic properties and great promise for real-world applications in HG and hydrogen storage. Characterization using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller (BET) adsorption analysis showed Co–Zn–B nanoparticles attached to the GP surface. The catalytic activity was further improved by treating the nanocomposite with NaOH to remove zinc from the composite matrix and increase the active surface area. The BET measurements showed the specific area of the treated material increasing from 86.4 to 120.2 m 2 /g. The effects of temperature, NaBH 4 concentration, and NaOH concentration on HG were investigated. The measured HG rate was 2180 mL/(min·g) at 30 °C in a 5 wt.% NaOH + 3 wt.% NaBH 4 solution, much higher than rates obtained for unsupported Co–Zn–B catalysts. The stability of the fabricated composite catalyst was also explored. [ABSTRACT FROM AUTHOR]

In this study, a nanoporous Co–B–TiO 2 framework was prepared by in-situ chemical reduction under sonication. After the introduction of nano-TiO 2 particles to a Co–B alloy, the specific surface area of the composite was substantially improved from 47.2 to 89.6 m 2 /g. The morphology was also changed from aggregated nanoparticles to a nanoporous framework. Furthermore, the catalytic activity was significantly enhanced for the hydrolysis of NaBH 4 . A high rate of hydrogen generation was found at 1980 mLmin −1 g −1 at 30 °C in a 5 wt% NaOH+1.5 wt% NaBH 4 solution, and the rate was much faster than those obtained with undoped Co–B catalysts. The activation energy of the hydrolysis was 30.93 kJ/mol, which is comparable to that of noble metal-based catalysts. The stability of the fabricated composite catalyst was also explored. [ABSTRACT FROM AUTHOR]

Hydrogen production through chemical processes has received considerable attention. Replacing precious-metal-based catalysts in NaBH 4 hydrolysis entails challenges such as the low durability and efficiency of non-precious metals. Here, carbon nanofiber (CNF)-supported NiCo 2 O 4 and CoB were synthesized to form a burr-shaped rod-like catalyst (CNF-NiCo 2 O 4 -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, NaBH 4 hydrolysis was catalyzed using CNF-NiCo 2 O 4 -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 NaBH 4. • Novel method for synthesis of a composite catalyst, CNF-NiCo 2 O 4 -CoB, is proposed. • Proposed catalyst achieves significantly higher hydrogen production rate than CoB. • Lowest activation energy of 38.32 kJ mol−1 is achieved. • CNF-NiCo 2 O 4 -CoB entails high durability, simple synthesis, and easy application. [ABSTRACT FROM AUTHOR]

• A catalyst with finely dispersed Ru(0) was developed for H 2 generation from NaBH 4. • Ru particles (2 nm) were dispersed on TiO 2 nanospheres loaded on layered Ti 3 C 2. • High catalytic activity was realized at 0.33 wt% Ru loading. • The catalyst retained 80% activity after five cycles of NaBH 4 hydrolysis. To improve the utilization rate of the precious metal, ruthenium, TiO 2 nanospheres containing oxygen vacancies are grown on the surface of layered Ti 3 C 2 , and superfine Ru nanoparticles are fixed on the surface of TiO 2 nanospheres via hydrogen reduction of a Ru precursor. The presence of titanium in a low oxidation state is verified by X-ray photoelectron spectroscopy, thus confirming the existence of oxygen vacancies. Spherical aberration transmission electron microscopy studies indicate the dispersion of uniform Ru nanoparticles (average diameter: ~2 nm) on TiO 2 , and the existence of a part of Ru in the form of single atoms. The catalyst with 0.33 wt% Ru loading exhibits the best catalytic performance in the hydrolysis of NaBH 4 (NaBH 4 hydrolysis rate at 303 K is 60 L·min−1·g Ru −1). Further, the catalyst performs well even after five cycles of use. [ABSTRACT FROM AUTHOR]

• Highly stable cobalt nanorods were facilely anchored on T 4 N 3 T x MXene. • Ti 4 N 3 T x provided good stability and dispersion for cobalt nanorods catalysts. • Co/T 4 N 3 T x composite demonstrated superior activity and stability for the hydrolysis of NaBH 4. Cobalt-based catalysts are widely used for borohydride hydrolysis, but they are limited by their poor activity and stability. In this study, highly stable cobalt nanorods were facilely anchored on T 4 N 3 T x MXene via hydrothermal synthesis. T 4 N 3 T x effectively prevented the aggregation of the cobalt nanoparticles. The Co/T 4 N 3 T x composite demonstrated superior activity and stability for the hydrolysis of sodium borohydride, which displayed a high hydrogen generation rate of 526 mL g−1 min−1 at 30 °C. The catalyst retained 75% of its initial activity after 15 cycles, which is much higher than previously reported results. Density functional theory (DFT) calculations showed that the Gibbs free energy of hydrogen adsorption on Co/T 4 N 3 T x is close to 0 eV, further confirming the excellent activity of Co/T 4 N 3 T x. These results indicate that the prepared Co/T 4 N 3 T x catalyst is promising for use in hydrogen production via the hydrolysis of borohydride. [ABSTRACT FROM AUTHOR]