Preparation And Performance Of Cobalt-Based Hydrogen Evolution Electrode For Water Electrolysis

Hydrogen energy has received a lot of attention for its abundant sources and its advantages such as green and clean.The preparation of hydrogen by electrolysis of water is the ideal clean hydrogen energy production method,and the key to its commercialization lies in the preparation of hydrogen evolution reaction（HER）catalysts.Currently,platinum,a precious metal,is recognized as a material with excellent HER performance,but the scarcity of platinum resources and its high price hinder the large-scale commercial production and application of platinum-based catalysts.Therefore,the development of inexpensive transition metal HER catalyst materials has become an important research direction for future development and is highly sought after.In this thesis,a series of cobalt-phosphorus alloy electrodes（Co-P/NF）with different P-element contents were prepared with nickel foam（NF）as the substrate and transition metal cobalt as the core element,and a series of platinum/cobalt-phosphorus alloy electrodes（Pt/Co-P/NF）with different Pt contents were prepared by further introducing a small amount of precious metal Pt on Co-P/NF,and their HER performance was studied.The main contents of the paper include:Firstly,a series of Co-P/NF electrodes were prepared by electrochemical deposition of cobalt-phosphorus alloys with constant current method using nickel foam as the substrate,and the electrode materials were characterized by SEM,XRD and XPS,and their HER performance was investigated.The experimental results showed that the best HER performance was achieved when the atomic ratio of Co to P in the cobalt-phosphorus alloy was 2:1,with an overpotentialη₁₀of 49m V and a Tafel slope of 34.2 m V·dec^-1.It can be seen that the prepared amorphous cobalt-phosphorus alloy electrode catalyst has good stability while retaining the loose and porous structure of nickel foam,which forms a large number of active sites and facilitates the contact of solution and hydrogen release.Secondly,based on the Co-P/NF electrode,a small amount of Pt was further electrochemically deposited on the surface of the cobalt-phosphorus alloy by a constant voltage method to construct a Pt/Co-P/NF electrode,and the electrode material was characterized by SEM,XRD and XPS.The HER performance study showed that the introduction of a small amount of Pt element significantly improved the catalyst performance with an overpotentialη₁₀of 22 m V and a Tafel slope of 20.4 m V·dec^-1.It can be seen that the introduction of a small amount of Pt is beneficial to improve the HER performance of the catalyst without significantly increasing the cost.Finally,the HER comprehensive performance of the above two electrode catalysts,Co-P/NF and Pt/Co-P/NF,was compared with that of the commercial 20%Pt/C/NF electrode.The results show that after 1000 cycles,the overpotential changes?η₁₀₀of the three are 6,13 and 41m V,respectively,which shows that the prepared cobalt-phosphorus alloy catalysts have better durability.The Faraday efficiency of all three catalysts could be maintained above 93%in 50 min operation at a current density of 100 m A·cm^-2.The hydrogen evolution reaction rates of Co-P/NF,Pt/Co-P/NF and 20%Pt/C/NF electrodes were 1.02,1.18 and 1.23 m L·min^-1·cm^-2,respectively.