Design,Preparation And Electrochemical Properties Of Iridium-Based Catalysts

Proton exchange membrane cell(PEM)has the advantages of fast hydrogen production rate,high purity and good safety coefficient.However,it requires more for electrode materials,because some commonly used electrode materials,such as metal oxides and metal hydroxides,can not exist stably under acidic conditions.Therefore,some precious metal catalysts are used in industry.For example,the catalyst of hydrogen evolution reaction(HER)at cathode mostly used platinum(Pt)base material.Catalysts of oxygen evolution(OER)at anode mostly use ruthenium(Ru)and iridium(Ir)based materials.These metals are expensive because of their low reserves in the earth’s crust.Therefore,it limits its large-scale application.Through specific means,a certain amount of non-precious metals and Pt,Ru,Ir and other precious metals are integrated to form compounds that can exist stably under acidic conditions,while maintaining the catalytic activity and stability of these precious metals.Such a material can reduce the cost of the electrode material.Based on this idea,we designed,synthesized two iridium based material catalysts and performed a series of characterization.The related OER performance of these catalysts has been tested.The main results can be summarized as following:1.A nanoparticle of iridium nickel oxide has been synthesized by a simple solve thermal method.The optimal synthesis conditions were determined by controlling the reaction time and temperature.The great OER performance of this particle was tested in 0.5 M H2SO4 electrolyte.When the current density is 10 mA cm’2,after iR corrected,the over-potential of iridium oxide is only 232 mV.The stability of the iridium nickel oxide was proved by cyclic voltammetry test of 2000 cycles and time-voltage test of 35 hours.In addition,it exhibits excellent electrochemical performance in acidic,neutral,and alkaline electrolytes.2.A kind of cobalt tetroxide nanosheet doped with the metal iridium has been synthesized on commercial carbon paper by a simple two-step chemical reaction of electrochemical deposition and high-temperature decomposition method.The oxidation temperature was regulated for the controllable synthesis.Through the electrochemical tests on the materials synthesized under optimal conditions in a highly acidic electrolyte of 0.5 M H2SO4,we found that when the current density was 10 mA cm-2 and 100 mA cm-2,the overpotential of the iridium-doped cobalt tetroxide nanosheet material was only 220 mV and 270 mV.Moreover,this synthesis method is very simple and does not require extreme conditions such as high pressure and vacuum,providing a reference for the synthesis of high-performance acidic OER catalysts.