Preparation Of Co-based Transition Metal-based Catalysts And Their Application In Water Electrolysis For Hydrogen Production

Hydrogen energy is considered as an ideal alternative energy in the future due to its advantages of cleanliness,high efficiency and convenient storage.Hydrogen production by water electrolysis is one of the technologies for hydrogen production at present.But the huge power and noble metal catalyst cost limit the application of water electrolysis technology.Therefore,it is particularly urgent to design non-noble metal catalysts with low cost,wide range of sources and excellent performance.On one hand,this dissertation designed a cobalt based electrocatalyst for hydrogen evolution reaction,which can reduce the catalyst cost and obtain excellent catalytic performance.On the other hand,in order to solve the problem of slow anodic kinetics and high overpotential,this dissertation adopted the cooperative hydrogen production strategy of glycerol oxidation reaction substituting for oxygen evolution reaction,which can not only reduce the overall water electrolysis overpotential,but also produce high value-added products of formate on the anode.Specific research contents are as follows:(1)Hierarchical core-shell nanorod array electrocatalyst(CoP@a-CoB HRNA)with crystalline CoP as the core and amorphous CoB nanosheets as the shell was synthesized by hydrothermal-phosphatide-chronoamperometry-boration strategy,showing excellent hydrogen evolution reaction performance in 1.0 M KOH and 0.5 M H2SO4 solutions with the overpotentials of 56.3 and 81.2 mV at the current density of 10 mA cm-2,respectively.Moreover,obtained electrocatalyst shows outstanding stability.The performance tests and structural characterization results show that the unique structure with crystalline CoP nanorods as the core and amorphous CoB nanosheets as the shell not only provides abundant active sites,but also promotes rapid charge transfer.Furthermore,the strong interaction between crystalline CoP and amorphous CoB effectively regulates the electronic structure of active sites,further promoting the enhancement of hydrogen evolution performance.(2)A high entropy alloy bifunctional catalyst(HEA-CoFeNiCuP)containing five elements,Co,Ni,Fe,Cu and P,was constructed by a simple one-step electrodeposition method.The performance test results showed that the catalyst exhibited good performance for hydrogen evolution and glycerol oxidation in alkaline solution.The contrast tests revealed the existence of different intermediates and products in the glycerol oxidation process,which clarified the reaction path of glycerol oxidation.Theoretical calculations show that the Co site coordinated with Fe and Ni in HEACoFeNiCuP is the main active center for hydrogen evolution with the optimum Gibbs free energy for hydrogen adsorption.In addition,the Fe site plays an important role in promoting glycerol oxidation.Finally,the glycerol oxidation-assisted electrolytic hydrogen production electrolytic cell(HEA-CoFeNiCuP‖HEA-CoFeNiCuP)was constructed by using HEA-CoFeNiCuP as the anode and cathode catalysts.Compared with conventional water electrolysis,this electrolyzer not only greatly reduces the input voltage and the power consumption,but also yields a formate product with high added value.