Preparation Of Copper-doped Ceria Composite Material And Its Electrocatalytic CO₂ Performance

During the development of modern society,the use of fossil fuels such as coal,oil,and natural gas has increased dramatically,causing the concentration of CO₂ in the atmosphere to increase year by year,resulting in an intensified greenhouse effect.On the one hand,the carbon dioxide electric reduction technology driven by the electric energy produced by renewable energy can realize the efficient storage of electric energy.On the other hand,it is an important way to solve the current energy and environmental problems by using high-value-added industrial carbon dioxide while reducing carbon emissions.Compared with C₁ products,the reduction of CO₂ to multi-carbon products above C₂ has greater research value and application prospects.Among them,metal Cu is currently the only catalyst that can reduce CO₂ to multi-carbon products,however,the catalytic effect of Cu currently has the following shortcomings:The product has low selectivity,poor stability,and high over-potential.This thesis mainly solves the problem of Cu selectivity and stability in the electrocatalytic CO₂ reduction process.By doping Cu into the stable CeO₂ lattice,the stability of the catalyst and the selectivity of the product are improved.The main research contents of this paper are as follows:（1）Constructed a complete electrocatalytic CO₂ reduction reaction system,using cerium nitrate as a precursor,cerium oxide is obtained by air firing,and Cu-CeO_2-X catalyst is prepared by doping copper ions into the cerium oxide crystal lattice by a precipitation method.A series of characterization and electrocatalytic CO₂ reduction performance tests were carried out on the composite catalysts of cerium dioxide and Cu doped amount obtained at different calcination temperatures.The results showed that the composite material obtained with CeO₂calcined at 450℃as the carrier and the Cu doping amount was 7.78 wt.%has the best performance for the electrocatalytic reduction of CO₂.At-1.3 V（vs.RHE）potential,the highest Faraday efficiency of ethylene is 27.14%.（2）One-step hydrothermal synthesis of carbon spheres using glucose solution,and then use the carbon spheres as a template to obtain hollow spherical cerium oxide.The copper ion-doped hollow spherical cerium oxide(Cu-CeO_2-X-TC)is prepared by precipitation method.The experimental results show that,compared with the copper ion-doped cerium oxide(Cu-CeO_2-X)prepared without a template,the composite material obtained by introducing a carbon template shows more excellent catalytic selectivity and stability for the electroreduction of CO₂to ethylene.The Faraday efficiency of ethylene is as high as 38.15%,which is mainly due to the carbon template method which improves the uniformity of CeO_2-X structure.（3）Using cerium nitrate as the precursor,a two-dimensional flake cerium oxide was prepared by adding P123 triblock copolymer in the hydrothermal process.Then copper ions are doped into cerium oxide by precipitation method to prepare copper-doped flake cerium oxide composite material(2D Cu-CeO_2-X),the research results show that the addition of surfactant P123 induces cerium oxide to form a two-dimensional flaky structure,which increases the specific surface of cerium oxide,which is more conducive to the doping and dispersion of copper,the Faraday efficiency of ethylene is further improved to 42.01%at a voltage of-1.3 V（vs.RHE）.