Preparation Of Nickel Cobalt Based Composite Materials And Their Catalytic Performance For The Hydrolysis Of Sodium Borohydride

Sodium borohydride has attracted much attention due to its high theoretical hydrogen content,relative safety,and renewable products.However,the slow rate of hydrogen liberation from sodium borohydride spontaneous water hinders its widespread application.Therefore,the preparation of stable and efficient catalysts has become a focus of research.At present,some precious metal catalyst materials have the problem of reduced activity due to factors such as easy aggregation of active metals and collapse of carrier materials.In response to these problems,this paper proposes to use inexpensive transition metal catalysts to achieve rapid hydrolysis of sodium borohydride to produce hydrogen at room temperature.Transition metal catalysts have high catalytic activity.If they can be loaded onto carrier materials with high stability and high specific surface area to achieve stable dispersion of active metal particles,the composite material catalyst prepared under the synergistic effect of the two is expected to achieve the application of sodium borohydride hydrogen production system in future fuel cell vehicles.This article uses solvent thermal method,electrospinning method,chemical reduction method,gas reduction method,and high-temperature calcination method to successfully prepare CNF-NiCo₂O₄-Co B,CMF-Co O-Co B Ru@Co Al-LDH Three cobalt based composite catalysts were characterized for their structure,morphology,and composition.The activity of the catalysts in promoting the hydrolysis reaction of sodium borohydride and their cyclic stability after multiple uses were tested.The main conclusions of this article are as follows:（1）The burr shaped rod-shaped structure formed by synthesizing polyacrylonitrile nanofibers loaded with NiCo₂O₄ nanoneedles was used as a composite carrier to load Co B nanoparticles.This structure effectively suppressed the aggregation of Co B particles.Through testing,it was found that CNF-NiCo₂O₄-Co B can efficiently catalyze the hydrolysis reaction of Na BH₄.At 30℃,the hydrogen release rate is 5225 m L·min^-1·g^-1,and the activation energy is 38.32 k J·mol^-1,After 9 repeated tests,it can still maintain 82.5%catalytic activity.The research shows that the carrier with high specific surface area makes the active metal particles well dispersed and exposes more active site.Meanwhile,the composite carrier has a stable structure,which enhances the cyclic stability of the catalyst.（2）The CMF-Co O-Co B catalyst was prepared by loading flake like Co-MOF derivatives on carbonized melamine foam（CMF）as a composite carrier,and then chemically reducing the supported Co B particles.It was found that CMF-Co O-Co B has good catalytic activity and cyclic stability for the hydrolysis of Na BH₄.At 30℃,the hydrogen release rate is 6974 m L·min^-1·g^-1,and the activation energy is 35.05 k J·mol^-1.After 5 cycles of testing,it can still maintain 80.4%of the initial activity.This has great application prospects in catalyzing the hydrolysis of sodium borohydride to produce hydrogen.（3）Synthesis by loading Ru nanoparticles on Co Al-LDH nanospheres Ru@Co Al-LDH Nanocatalysts are used to catalyze the hydrolysis of Na BH₄.Firstly,Co Al-LDH was synthesized by solvothermal method,and then Ru nanoparticles were loaded by hydrogen reduction method for surface modification.At 30℃,the hydrogen production rate reached44.34 L·min^-1·g _Ru^-1,and the activation energy was 38.83 k J·mol^-1.After 8 cycles,the catalytic activity retention rate was 74.5%.Co Al-LDH Nanoflower spherical support provides a large specific surface area,which forms a synergistic effect with Ru nanoparticles and improves the comprehensive performance of the catalyst.