Research On Electrocatalysis Reduction Of Co₂ By The CoO,Ag,Pb ModifiedDy₂O₃

Since the Industrial Revolution,the burning of fossil fuels has caused a large amount of CO₂ emissions,and the content of CO₂ in the atmosphere has been increasing,which has brought a series of environmental problems,such as climate warming,sea level rise,and changed in water balance,which have an impact on the ecological environment.On the other hand,people's demand for fossil fuels such as petroleum is constantly increasing,and global energy shortages have threatened human survival and development.The catalytic conversion of CO₂ into reusable organics has become a hot topic for scholars.Among many catalysis methods,the electric power provided by solar energy,wind energy,and water energy for the electrocatalysis of CO₂ to organics is considered to be the most promising way to solve these two problems at the same time.Electrocatalytic reduction of CO₂ has its unique advantages,its potential is controllable,and its selectivity is high.The catalyst is a key factor for catalytic reaction.First of all,superior performance catalysts have a strong adsorption of CO₂.Adsorption is the first step in catalytic reactions.Secondly,the catalyst must have high catalytic activity.Metals and metal compounds are often used as active centers for catalytic reduction of CO₂,Different metals have different catalytic activities for CO₂ reduction,and the catalytic activity of different crystal planes of the same metal is also different.Generally,metals with high index crystal planes show higher catalytic activities.In response to the above issues,I have carried out four parts of work.1.An anodic oxidation method was used on rare earth metal dysprosium sheet to prepare the Dy₂O₃ that had strong adsorption of CO₂.By screening the anodic oxidation voltage and time for the preparation of Dy₂O₃,the material Dy₂O₃ prepared at an anodizing voltage of 15 V and an anodizing time of 2 h has a resistance of 7.5 k?.The adsorption amount of CO₂ was1.13nmol·cm^-2 and the adsorption of Ar is 0.32 nmol·cm^-2 on Dy₂O_3.The Dy₂O₃ had a strong adsorption of CO_2.The adsorption of CO₂ is 3.5 times that of Ar on Dy₂O₃.2.The net structure of CoO was deposited on the surface of the Dy₂O₃ by the method of pulse deposition.When the pulse deposition CoO cycle was 20,the prepared catalyst net shaped CoO modified Dy₂O₃ showed the highest CO₂ reduction efficiency at a voltage of-0.92V,with a maximum CO₂ current conversion efficiency of 61.6%.Compared with other pulsed deposition cycles,the prepared CoO modified Dy₂O₃ showed higher current conversion efficiency of reduction CO₂ at a lower reduction potential.After 7 hours of CO₂ electrocatalytic reduction reaction,the yield of methanol as main product was 326.9?mol^-1·L·cm^-2,and the yield of ethanol was 23.2?mol^-1·L·cm^-2.CoO modified Dy₂O₃ catalysts showed higher selectivity for methanol.The selectivity of methanol is as high as 93.4%.3.Regulate the crystal face of Ag deposited on the surface of Dy₂O₃ by the polyvinylpyrrolidone and sodium dodecylbenzene sulfonate.Ag electrodeposited without the addition of any surfactant exhibits?111??200??220?crystal plane.A single crystal plane?111?of Ag was exhibited by adding sodium dodecylbenzene sulfonate.The crystal planes of Ag regulated by polyvinylpyrrolidone are?111??200??220??311?.Compared with the other two catalysts,Ag/Dy₂O₃ with high index crystal plane?311?of Ag showed higher CO₂ reduction efficiency and faster reaction speed.The reduction of CO₂ to methanol by Ag/Dy₂O₃ with high index crystal plane of Ag is 6.8 times that of Ag/Dy₂O₃ with a single crystal plane?111?of Ag,and 3.7 times that of Ag/Dy₂O₃ with a low index crystal plane of Ag.4.Metal Pb was deposited on Dy₂O₃ by pulse deposition.The crystal planes of Pb regulated by sodium dodecylbenzene sulfonate showed higher index crystal planes?331??420?than these without the addition of surfactants.And It has the highest CO₂ current conversion efficiency at a voltage of-1.50V,and the current conversion efficiency of reduction CO₂ is 62.3%.After 7hours of measurement,the amount of the reduction of CO₂ to methanol on higher index crystal planes Pb/Dy₂O₃ was 561.5?mol^-1·L·cm^-2.The reduction of CO₂ to methanol by Pb/Dy₂O₃with a high index crystal plane?331?and?420?.of Pb is 2.4 times than that of Pb/Dy₂O₃ without high index crystal plane?331?and?420?of Pb.