Preparation And Study On The Electrocatalytic Performance Of Cu-Fe-O Catalysts

Excess consumption of various non-renewable energy sources and large amounts of industrial waste gas emissions have led to problems such as the greenhouse effect,energy crisis and environmental pollution.These challenges have made human society’s development face unprecedented obstacles.It is greatly important to solve current environmental issues and achieve the“dual carbon”goals as soon as possible by utilizing renewable power systems to replace fossil fuels for clean energy and chemical production.The catalyst electrode is the core component of the electrocatalytic process.Designing and preparing an efficient and stable catalytic electrode has become a crucial limiting factor in electrocatalytic technology development.Traditional precious metal materials（Ag,Pt,Pd,etc.）are favored in existing research and applications due to excellent efficiency and stability.However,high prices,scarce reserves and relatively slow catalytic processes have limited their development.Therefore,to further improve catalytic efficiency and reduce catalyst costs,it is urgent to design catalytic electrodes with high activity,stability and low cost.This paper studied the design and development of copper-based and iron-based binary transition metal oxide catalytic electrodes.The catalyst’s composition and structure were regulated.The relationships between preparation conditions and the morphology,electronic structure,exposed crystal surface,adsorption performance and active site distribution of the catalyst were studied in depth.The connections between catalyst structure and performance were explored.The primary research results are concentrated in the following three aspects:1.CuInS₂/CuFeO₂ thin film electrode with oxygen vacancy and S-O bond was prepared by introducing a surfactant in electrodeposition.It was used for photoelectrocatalytic CO₂ reduction to produce methanol and showed excellent methanol production performance.Introducing oxygen vacancy improved the composite film’s light absorption and photocatalytic activity.Introducing oxygen vacancy also optimized the adsorption energy barrier of the*CO intermediate,facilitating the reaction’s*CHO direction for methanol production and thus improving the electrocatalytic activity and methanol selectivity.The oxygen vacancy enabled a unique S-O bond formation at the CuInS₂ and CuFeO₂ interface,which enhanced the composite film’s photocatalytic activity by improving carrier lifetime.The S-O bond also reduced the average energy barrier required for each reaction step,improving electrocatalytic activity.Furthermore,the S-O bond stabilized the oxygen vacancy structure,enhancing catalyst stability.Through synergistic catalysis of the oxygen vacancy and S-O bond,efficient CO₂ reduction to produce methanol was achieved.The 12CIS/CFO-Vo-SO composite thin film electrode prepared with PVA dosage of 12 mg m L^-1 has a methanol concentration of 0.31m M at-0.700 V（vs.SCE）potential for 1 h,shows 90%Faradaic efficiency of methanol product,which is twice as high as that of the CIS/CFO thin film electrode.2.The boron-doped CuFe₂O₄ catalyst（CuFe₂O₄-B）was prepared by the solution combustion method for the electrocatalytic reduction of CO₂and N₂ to synthesize urea.Boron doping reduced the overpotential required for CO₂ activation,and the prepared CuFe₂O₄-B electrode exhibited good urea synthesis performance.Furthermore,organic fluorine was introduced into CuFe₂O₄-B also via the solution combustion method.The resulting CuFe₂O₄-BF catalyst surface had a unique carbon-fluorine coating structure.Introducing fluorine improved the electrode’s physical and chemical adsorption capacity for N₂ and CO₂,facilitating activation of the catalyst to the gases.This improved intermediate coverage on the electrode surface and promoted the C-N coupling reaction.The carbon-fluorine coating formed a superhydrophobic interface on the catalyst surface,enhancing electrode stability while limiting direct electrolyte contact with the catalytic electrode.This inhibited the side reactions of hydrogen evolution and ammonia production,steering the reaction towards C-N coupling.Boron doping and fluorine introduction respectively promoted the gas adsorption,activation and C-N coupling stages of urea synthesis.The CuFe₂O₄-BF catalyst prepared by adding0.234 g H₃BO₃ and 200μl 60%PTFE emulsion in solution combustion method exhibited excellent urea synthesis performance.At-0.800 V（vs.Ag/Ag Cl）potential,the urea formation rate was 5.32 mmol h^-1 g^-1,the Faradaic efficiency was as high as 46.25%,the structure remained stable after 20 h of reaction.3.By introducing KNO₃ in the solution combustion method for preparing CuFe₂O₄,the CFO-111 catalyst with（111）as the dominant crystal plane was successfully prepared.Furthermore,the CFO-111powder was made into a 3DCFO-111 electrode using 3D printing technology for alkaline electrolysis water hydrogen evolution reaction.KNO₃ induced microstructure and structural changes in the catalyst,inhibiting the inherent（311）crystal plane and generating a new（111）crystal plane.The catalyst’s microstructure was replaced by a porous skeleton structure.This KNO₃-induced porous skeleton improved the specific surface area,while 3D printing gave the active sites spatial distribution,both enriching exposed active sites.The CuFe₂O₄（111）crystal plane showed stronger H₂O adsorption capacity and larger H₂O dissociation enthalpy than the（311）plane,with more suitable*H binding strength,which is the source of the catalyst’s high intrinsic activity.The3D printed electrode has fewer phase compound interfaces,enabling higher charge transfer performance.The high intrinsic activity,abundant active sites and excellent charge transfer underpin the 3DCFO-111electrode’s high hydrogen evolution performance.The 3D printed and changed crystal face orientation 3DCFO-111 electrode prepared with0.095 g KNO₃,required only 39 and 160 m V（vs.RHE）overpotential at10 and 100 m A cm^-2 hydrogen evolution current density,with a Tafel slope as low as 33 m V dec^-1.The 3DCFO-111 electrode maintained excellent hydrogen evolution performance and structural stability during2000 cycles of linear voltammetry scan and 40 h of electroanalytical experiments.