Preparation Of Organic-Inorganic Composite Electrode And Its Application In Carbon Dioxide Reduction

In the 21st century,mankind faces the use of unsustainable fossil energy and theconsequent carbon emissions.Carbon dioxide,as one of greenhouse gases for human beings,is converted into different carbon-based compounds through chemical methods,which not only reduces the concentration of CO2,but also achieves the purpose of storing energy.Electrochemical and photochemical catalytic reduction of carbon dioxide have been widely studied,but the researchs of photocatalysis or electrocatalysis alone also reflect their deficiencies.Electrocatalytic processes require high external voltages,while photocatalytic materials demonstrate low absorption in visible light.Therefore,the photoelectrocatalytic system is designed to combine the advantages of photo-and electro system to achieve the goal of photoelectric synegetic catalysis in the reduction of carbon dioxide.In this dissertation,the photocathodes were prepared by using the interaction between inorganic semiconductors and organic ligands in photoelectrocatalytic systems.The photoelectrocatalytic systems include the following two parts:（1）Preparation of photocathodes using foamed nickel and graphite sheets as substrates,using inorganic semiconductor surface OH^-groups as anchor points for formation of dense monolayers,and reaction of organosilanes(RSiX₃,where R is an alkane Base,X is a leaving group,such as chlorine,alkoxy.Using a monolayer of silane on the oxidized surface,the main advantage is the rapid formation of a covalent bond between the base and the anchor group.The bond forms a stable monolayer,but also allows easier chemical modification without compromising the integrity of the monolayer.（2）In this paper,two kinds of three-electrode systems were used.In the first system,we prepared the inorganic-organic composite electrode as the photocathode,the BiVO₄ electrode as the photoanode,and the calomel electrode as the reference electrode.We examined the organic ligands.Effect on CO₂ reduction;second system uses inorganic-organic composite electrode as photocathode,Pt electrode as photoanode,calomel electrode as reference electrode to investigate the effect of different organic ligands on semiconductor bandgap and CO₂ The effect of the selectivity of the reduction process product.（3）The light intensity of the light source is calibrated to 200 mW/cm² by standard solar cells.In addition,it was confirmed by ¹³CO₂ isotope labeling that the products produced by the photovoltaic system came from carbon dioxide.