Non-noble Metal Bismuth Based Materials For Electrocatalytic Nitric Oxide Reduction To Ammonia

In recent years,NO emission caused by human activities and industrial production has caused serious environmental problems.In order to meet the NO emission standards set by various countries,the research on NO emission reduction methods has attracted much attention.Electrocatalytic NO reduction to NH₃（NORR）,which is driven by renewable electricity to generate chemically value-added NH₃,is green and environmentally friendly,and is a NO emission reduction method with broad research prospects.The key to NORR efficiency lies in electrocatalysts.Although existing noble metal materials,transition metal composites,and non-metallic materials have been shown to have high NORR activity,cost factors and competitive hydrogen evolution reaction（HER）inhibition make these catalysts have certain limitation.As a non-precious metal that is insensitive to HER,Bi has excellent performance in electrocatalytic CO₂reduction,N₂ reduction,and O₂ reduction.Therefore,the performance of Bi-based catalysts in NORR reaction is also worthy of exploration and research.We prepared two Bi-based catalysts by electrochemical reduction and high-temperature annealing,respectively.After physical and chemical characterization of the materials,the NORR performance was explored by electrochemical testing,and the density functional theory（DFT）calculation was further used.After analyzing the reaction path and mechanism,the research results obtained are as follows:1.A morphology control strategy is proposed to obtain Bi nanodendritic morphology with tip electron effect by electrochemical reduction.We determined its high-efficiency NORR performance in neutral media through electrochemical tests,reaching the highest NH₃ Faradaic efficiency of 89.2%at-0.5 V vs.RHE,while obtaining a maximum ammonia production rate of 1194μg h-~1 mg-~1_cat.,DFT calculated The NORR reaction path and electron transfer mechanism on the Bi（012）crystal plane were determined,and the hydrogenation of*NO to*NOH was determined as the rate-controlling step.At the same time,the competitive adsorption of H₂O and NO on the crystal plane was analyzed,and the lower free energy of NO adsorption It indicated that NO was more easily adsorbed and activated on the Bi surface,so HER was successfully inhibited.We successfully assembled a Zn-NO concept battery with Bi nanodendrites as the cathode,and obtained high power density and ammonia production rate.2.Based on the high performance of elemental Bi nanodendrites,the composite Bi@C of metallic Bi and non-metallic carbon materials was prepared by direct annealing of commercial bismuth citrate.High-density Bi@C core-shell nanoparticles are embedded in the carbon nanosheet framework.Bi@C can achieve higher NORR in neutral media,with the highest NH₃ Faradaic efficiency(FE_NH3)of 93%at-0.4 V vs.RHE and a maximum ammonia production rate of 1592.5μg h-~1 mg-~1_cat.at-0.7 V vs.RHE,while The Bi@C-based Zn-NO battery is also highly active for NORR in acidic media(FE_NH3:89.1%;NH₃ yield:761.16μg h^-1 mg^-1_cat.),and the Bi@C-based Zn-NO battery can stably discharge continuously for 6 h,and is When the discharge current was3 m A cm^-2,the maximum ammonia production rate was 355.6μg h^-1 cm^-2.