Construction And Oxygen Evolution Performance Of Electrocatalyst For Cobalt-based Phosphide

With the depletion of fossil energy and environmental pollution becoming more and more serious,it is urgent to develop and utilize green renewable energy.Hydrogen energy is regarded as a sustainable green new energy,which is attributed to its advantages such as zero pollution,less consumption,reduce greenhouse effect,high calorific value,convenient storage and transportation.Due to its advantages of environmental friendliness,high purity and no carbon emission,electrocatalytic decomposition of water has become one of the most prospective hydrogen production strategies among many hydrogen production technologies.However,the slow kinetics of anodic oxygen evolution（OER）for hydrogen production by electrolysis of water is a bottleneck problem that restricts its application.So far,precious metal oxides（Ir O₂and Ru O₂）have been considered as the most advanced OER catalysts due to their low overpotential.Unfortunately,their high cost and scarcity limit their large-scale use in industry.Transition metal phosphide electrocatalysts（Cu-Co-P and Co Fe P/Co Fe₂O₄）were prepared by low temperature phosphating calcination using layered bimetal-hydroxide（LDH）materials prepared by electrodeposition and hydrothermal method as precursors.The composition,structure and OER properties of the catalysts were systematically studied.The main research contents are as follows:（1）Co Cu-LDHs/NF precursors were obtained by electrodeposition,and then annealed in argon at low temperature to successfully prepare nanosheets Co-Cu-P/NF catalyst.The open network structure of Co-Cu-P/NF has a large surface area and a short diffusion path,which can provide a large number of exposed active sites for rapid mass transfer and gas release.In alkaline solution,on the one hand,the Co-Cu-P/NF exhibited excellent electrocatalytic perform,which can drive the current density of 10m A cm^-2with only 240 m V overpotential.On the other hand,the Co-Cu-P/NF was only a loss of activity of about 3%in long-term stability tests.Therefore,Co-Cu-P/NF was superior to most recently reported TMPs catalysts.（2）Nano-flower-like heterogeneous Co Fe P/Co Fe₂O₄ heterojunction was successfully prepared on nickel foam by hydrothermal and double cruciible selective phosphating methods.Due to its unique three-dimensional nano-flower-like structure and layered void,the synthesized Co Fe P/Co Fe₂O₄ exhibits outstanding OER electrocatalytic performance.The synergistic effect of Co Fe P and Co Fe₂O₄ plays a role in these four aspects:accelerating the electron/ion migration process;the electrochemical active area was enhanced;exposed a large number of active sites;accelerate the release of gases formed in the OER process.In the electrolyte of 1 M KOH,the overpotential of Co Fe P/Co Fe₂O₄ heterojunction can reach a high current density of 50 m A cm^-2with only 280 m V,which is superior among the most recently reported transition metal phosphates/oxide catalysts.