Experimental Study On Photocatalytic CO₂ Reduction By Pt And Cu Metal Modified TiO₂

The rapid increase in human demand for energy has brought the potential problems of energy shortage,and the large-scale use of fossil energy has brought about environmental problems such as air pollution and climate warming.CO₂ photocatalytic reduction technology converts greenhouse gases into usable organic fuels through the resource utilization of solar energy.It is a renewable energy technology that can alleviate the pressure on energy sources and reduce greenhouse gas emissions.This process has the advantages of zero pollution,low cost,and mild reaction conditions.In this paper,the Ti O₂ modification technology is controlled by metal deposition and doping,and the characteristics and mechanism of CO₂ photocatalytic reduction are analyzed in detail.This research has guiding significance for the future industrialization of CO₂.In recent years,due to the excellent properties and low cost of copper,copper-modified Ti O₂ has attracted widespread attention.In order to explore the effect of copper-based catalysts on the photocatalytic reduction of CO₂,the highly dispersed Cu⁺was incorporated into the Ti O₂ lattice by flame spray pyrolysis（FSP）.The synthesized Cu Ti catalyst showed much higher photocatalysis than the original Ti O₂.Activity and better stability,and obtain the highest yield of CO and CH₄ on Cu Ti-1.In addition,XPS and PL analysis confirmed that highly dispersed Cu⁺ions in the Ti O₂ lattice are very stable and effectively slow down the recombination of light-induced charges.The single metal modified catalyst can effectively improve the photocatalytic activity,but it cannot improve the selectivity of the catalyst at the same time.In order to increase the photocatalytic reduction activity of CO₂ and selectively reduce CO₂ to the target product,different Pt/Cu proportion alloy was deposited on the surface of Ti O₂,and a Ti O₂-Ptx Cuy photocatalyst was synthesized.The results show that alloy deposition with a certain Pt/Cu ratio significantly improves the photocatalytic activity of the catalyst and achieves selective reduction of the catalyst.The deposition of Cu significantly promotes the formation of CO and methane,and the deposition of Pt significantly inhibits the formation of CO.When the Pt/Cu deposition ratio is 0.4:0.6,the yield of methane is the highest and the selectivity of CH₄ products reaches 100%The corresponding quantum efficiency is also the highest.Finally,using in-situ diffuse reflection infrared Fourier transform spectroscopy,the reaction path of Ti O₂ photocatalytic reduction of CO₂ and the adsorption effects of the deposition of single metals Pt and Cu and alloys on the photocatalytic reduction of CO₂ And its mechanism of action.The analysis results show that the deposition of single metal Cu is favorable for the adsorption and conversion of CO₂,but not conducive to the adsorption of water vapor,that is,there is a competitive relationship between the adsorption of CO₂ and H₂O.The deposition of single metal Pt is favorable for the adsorption of H₂O,but not for the adsorption of CO₂.The deposition of platinum-copper alloy with a certain Pt/Cu ratio promotes the adsorption of CO₂ and H₂O at the same time,so that it can be selectively converted into the target product.