Preparation Of Low Dimensional Metal Oxides And Their Electrocatalytic Properties For CO₂ Reduction And Water Decomposition

In today’s world,the use of non-renewable energy is increasing year by year,which makes fossil energy face the danger of exhaustion.At the same time,there is a large amount of greenhouse gas carbon dioxide emissions.Therefore,using clean energy such as solar energy and wind energy to provide electric energy and reducing carbon dioxide gas to usable fuel and chemical supplies,electrocatalytic carbon dioxide reduction has become an effective solution to energy and environmental problems.However,the high C=O bond energy inCO₂,the close theoretical potential of various carbon-containing products and the existence of competitive hydrogen evolution reactions lead to low activity and poor selectivity of electrocatalytic carbon dioxide reduction reaction.In addition,the energy efficiency of the reaction system is low due to the high energy barrier and slow kinetic process of oxygen evolution reaction.Therefore,the design and development of high performance electrocatalyst for carbon dioxide reduction and oxygen evolution reaction is an effective method to solve the problem of energy shortage and environmental damageBased on metal oxides as the research object,this paper through morphology and heterogeneous elements doping,construct various,some low dimensional nanostructures regulate the geometric structure and electronic structure of materials,the catalytic performance of carbon dioxide reduction and oxygen evolution reaction was studied in order to reveal the structure,performance and structure-activity relationship of the catalyst,and to provide a new idea and basis for the development of high-performance catalysts.Based on this,the main research contents of this paper are as follows:1.Adoping solvothermal-calcination method,A series of Cu,Mo,W doped SnO₂two-dimensional ultra-thin nanosheets were prepared.The results show that the electron configuration and doping amount of doped metals have important effects on the electron structure of the catalyst,such as the d-band center.Among them,the Faraday efficiency of W-doped SnO₂ nanosheets to produce C1 and HCOOH products reached95.7%and 86.9%at-0.9V,respectively,due to their moderate D-band center and adsorption energy for intermediates in carbon dioxide reduction reaction,and the performance remained unattenuated for 10 h.2.Adoping solvothermal method,SnO₂ nanoparticles with a diameter of 5 nm were synthesized by adjusting the temperature and solvent of the feeding molar number system.The low dimension and small size of the nanostructure are helpful to improve the specific surface area of the catalyst,increase the active site of the reaction,and enhance the contact with the electrolyte.Benefit from this,its Faraday efficiency of producing C1 and HCOOH products at-0.9V electrocatalytic reduction of carbon dioxide reached 91%and 76%,respectively,and its performance remained unattenuated for 40 h.3.Adoping solvothermal-calcination method,MnCo₂O₄-Wiener wire with spinel structure was prepared.The morphology and electronic structure of the catalyst were controlled by changing the type of reactants,feed ratio and calcination temperature.When the current density is 10 mA cm^-2,the overpotential of the electrocatalytic oxygen evolution reaction is 276 mV and the Tafel slope is 105 mV dec^-1.The results show that the synergistic effect of Mn and Co helps to improve the flexibility of the catalyst,optimize the electronic structure of the catalyst and the adsorption energy of intermediates,and thus improve the performance of the catalyst.