Application Of Non-noble Metal Compounds In Electrocatalytic Oxygen Evolution Reaction And Formate Electro-synthesis

With the rapid development of economic and the dramatic increase of population,the energy that human beings required is increasing day by day.Human beings continue to mine and consume fossil fuels,leading to serious environmental problems and energy crises.With the burning of fossil fuels,the concentration of carbon dioxide in the atmosphere will increase sharply,which will lead to global warming,polar glacier melting and other adverse effects.The development of new clean energy storage and conversion technology or electrochemical reduction of carbon dioxide into high value-added liquid fuel or chemical substances can effectively alleviate the increasingly serious energy crisis.In this paper,non-noble metal catalysts were used as research objects,combined with SEM,XRD,XPS and other material characterization techniques,two studies have been carried out on electrocatalytic oxygen evolution reaction and electrochemical carbon dioxide reduction coupled with formaldehyde oxidation to realize the electrosynthesis of formate.The details are as follows:（1）A high-entropy oxide（Fe,Co,Ni,Mn,Zn）₃O₄ HEO-Origin with high specific surface area,abundant oxygen vacancies,low crystallinity was synthesized by the sodium borohydride reduction strategy at room temperature.The results show that HEO-Origin with low crystallinity exhibits excellent OER performance with an overpotential of 265 m V at a current density of 10 m A cm^-2,which is much lower than that of HEO-500℃-air.The excellent OER performance of HEO-Origin can be attributed to large surface area provides plenty of active sites and promotes the infiltration of electrolyte into the interior of catalyst.Abundant oxygen defects activate the surface atoms of the catalyst,regulate the electron distribution around the catalytic sites,optimize the adsorption and desorption of intermediates,and improve the electrocatalytic performance.Activating surface atoms of catalyst provides an opportunity to discover novel properties of high-entropy oxides and promotes its application in the field of electrocatalysis.（2）Using nanosheets Bi OCl synthesized by hydrothermal reaction as CO₂RR catalyst,using oxygen plasma treatment and then situ electrochemically reduced copper foam（R-P-CF）as the formaldehyde oxidation catalyst to realize formate electro-synthesis.The results show that the Faradaic efficiency of CO₂RR to produce formate catalyzed by Bi OCl is higher than 90%at the potential range from-0.86 to-1.16 V vs.RHE in 0.5 M KHCO₃ electrolyte.Onset potential of formaldehyde oxidation is-0.1 V vs.RHE in 1 M KOH electrolyte.At the potential range from-0.05 to 0.35 V vs.RHE,the Faradaic efficiency of formaldehyde oxidation to produce formate is higher than 90%.The voltage required for CO₂RR coupling FOR to reach a current density of 10 m A cm^-2 is only 1.004 V.Electrolysis for 2h at different voltages,the sum of Faradaic efficiencies of anode and cathode to produce formate is higher than180%.Electrooxidation of small molecules is an efficient and versatile strategy to reduce energy input and promote the synthesis of high value-added chemicals or fuels.