| Hydrogen has a very attractive application prospect as a green and environmentally friendly new energy source.Hydrogen production by electrolyzed water is considered to be the most promising technology because of its simple method,clear mechanism,and low cost.Reducing the energy consumption in the process of electrolyzing water has always been the goal pursued by scientific researchers.According to research,electrolyzed water reactions are divided into oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).Among them,the electron transfer process in the OER reaction is complicated and is restricted by the adsorption and desorption binding energy of the intermediate,resulting in the reaction usually requiring a high potential.The hydrogen evolution reaction is limited by the cost of precious metal catalysts and cannot be applied on a large scale.Therefore,it is necessary to further explore low-cost and high-activity water-splitting catalyst materials.In recent years,researchers have developed many transition metalbased hydrogen evolution/oxygen evolution catalysts,and these catalysts have shown excellent catalytic performance.However,due to the agglomeration effect of the metal catalyst during the preparation process,the catalytic performance is reduced.Therefore,the use of activated carbon as a metal catalyst carrier can not only effectively improve the catalyst dispersion,but also the good conductivity of the activated carbon and heteroatom doping also promote the electrocatalytic process effect.The preparation and OER performance of activated carbon supported Fe Ni alloy catalysts and the HER performance of heterogeneous nickel-based compound catalysts are discussed in this paper.Activated carbon(AC)prepared by polymer pyrolysis as a support for Fe Ni alloy can effectively improve the OER activity of the catalyst.XRD,XPS and TEM were used to deeply analyze the surface characteristics of the catalyst.Compared with monometallic(Fe or Ni)catalysts,binary alloy catalysts exhibited a low overpotential(η10 = 280 m V)comparable to precious metal catalysts(Ir O2).And Fe Ni@AC has a high conversion frequency of 0.019 s-1.It turns out that activated carbon supported alloy catalyst is one of the effective ways to develop low cost,efficient and environmentally friendly OER catalyst.Heterogeneous nickel catalysts were induced on activated carbon supports by pyrolyzing polymers in nitrogen.The experimental results show that the samples prepared in the alkaline solution(II-Ni@AC and III-Ni@AC)have a much higher SBET than the samples obtained in the neutral system(I-Ni@AC).Placing the sample in a strong alkaline solution after pyrolysis can effectively increase the mesoporous ratio of the activated carbon support.During post-treatment,it was observed that Ni(OH)2 and Ni O outer walls were formed around the metallic nickel,which induced the metallic nickel particles to aggregate to form hexagonal nanoflakes.The HER reaction has an overpotential of 152 m V at a current density of 10 m A cm–2 and a Tafel slope of 141.3 m V dec-1,which is superior to most carbon-based transition metal catalysts. |
