Preparation Of Cobalt/Ruthenium-Based Nanocatalysts And Their Performance In Catalytic Hydrogen Generation From Sodium Borohydride

Sodium borohydride has received much attention due to its high theoretical hydrogen storage content（10.8 wt%）and the green and safe hydrogen production reaction by hydrolysis.In natural environment,its hydrogen release process is slow and efficient catalysts need to be prepared to enhance its hydrogen production rate.Catalysts are mainly precious metal（e.g.ruthenium）and non-precious metal（e.g.cobalt）catalysts,the former is expensive but has high catalytic activity,the latter has lower catalytic activity but its production cost is relatively much cheaper.The active metals are often prone to agglomeration during the catalytic process,which leads to a decrease in their catalytic activity and causes problems such as low stability.Based on this,in this paper,three efficient catalysts,Co P-Ni Co P/NC,B-Ni Co P and Ru/Ni₂P,were prepared for Co/Ru-based catalysts by doping with heteroatoms（P and B）to design and regulate the microstructure of the catalysts.The main studies are as follows:（1）The cobalt-nickel precursor was prepared by solution impregnation and solvothermal method using Ni-BTC as the carrier,and finally Co P-Ni Co P/NC was generated in one step by low-temperature vapor phase phosphorylation.The Co P nanorods and Ni Co P grown on the catalyst surface are rich in active sites and also produced synergistic catalytic effects.This greatly reduced the apparent activation energy of the catalytic reaction and improved the catalytic hydrogen production rate.The experimental results showed that the hydrogen production rate of sodium borohydride catalyzed by Co P-Ni Co P/NC was as high as 7052m L·min^-1·g^-1 at room temperature,and the catalyst had good durability,maintaining 75%of the initial catalytic activity after 10 cycles of testing.（2）The rational design and controlled synthesis of multiple metal components based on their morphology and synergistic effects are the key to achieve efficient catalytic hydrogen production by hydrolysis for sodium borohydride.Herein,in this study,layered double hydroxide（Co Ni-LDH）was prepared as a precursor by ion exchange method using ZIF-67 as a template,followed by low-temperature phosphorylation to obtain Ni Co P hollow nanocages with hollow structures.Finally,boron（B）species were doped into Ni Co P to obtain B-Ni Co P nanocatalysts.After a series of performance tests,it was found that the highest catalyst activity was prepared with a cobalt/nickel molar ratio of 1:3.The highest hydrogen production rate was as high as 8170 m L·min^-1·g^-1 at 303 K,and 74%of the initial catalytic activity was maintained after six cycles of performance tests.（3）In order to improve the catalyst activity while keeping the cost under control,this paper combines the noble metal Ru with the metal phosphide Ni₂P.Firstly,hollow Ni₂P microspheres were synthesized,and the unique structure facilitated the diffusion of sodium borohydride solution.The catalytic performance was tuned by varying the Ru loading,and the best performance was found using 15 mg Ru Cl₃·x H₂O loading.The highest hydrogen production rate was up to 10219 m L·min^-1·g^-1 at 303 K.The catalytic activity decreased by only 12%after six hydrolysis tests.