Research On The CO₂ Electrocatalysis By The Au,Pb Modified Sc₂O₃ Catalyst

The greenhouse effect,seawater acidification and various extreme weather have caused major damage to the balance of natural ecosystems and human society,and the origin of this series of serious hazards is excessive CO₂ emissions.But atmospheric CO₂ is the main carbon source of life on Earth.Plants,algae and cyanobacteria use light energy to synthesize carbohydrates from CO₂ and water and produce oxygen as waste.Therefore,CO₂ is the essential carbon source for the survival of plants and animals.In recent years,many scholars have converted CO₂ into usable chemicals by simulating the photosynthesis of green plants.Photocatalysis and electrocatalysis are considered to be the most promising methods of transformation in most processes.Photocatalysis converts the light energy in nature into chemical energy,using water as a hydrogen source,and powered by sunlight.It is a clean and environmentally friendly technology.Therefore,it has received extensive attention in the field of CO₂ reduction,but it is difficult to activate due to its inherent inertness.The catalyst has weak absorption for visible light,high recombination ratio of electrons and holes,poor adsorption performance to CO₂,low product selectivity,and a low conversion rate,which cause photocatalytic reduction of CO₂ to be full of challenges.Electrocatalysis is based on electrons as the main part of the reaction,and the whole process is green and clean.The process of catalyst is electrical energy to convert into chemical energy,which the energy can be converted from continuous renewable energy.The reaction is carried out under normal temperature and pressure,reaction conditions.The equipment requirements are simple,and the whole reaction process is easy to control,and only external parameters are controlled such as applied voltage,catalyst type,etc.So electrocatalysis is the preferred way to convert CO₂,and the choice of catalyst is the core for electrocatalysis.Of the many catalysts,rare earth catalysts are a good choice for strong anti-reduction ability at high negative potential,good stability,high low-temperature catalytic activity,few intermediate products and strong product selectivity,and are destined to become an excellent electrocatalyst.In this paper,the material particles modified Sc₂O₃ catalyst was selected as the research object,and the Sc₂O₃ NPs catalyst was prepared by electrochemical anodization on the metal scandium substrate.The SEM showed that the Sc₂O₃ NPs catalyst was the nanorod-like structure.The XRD data showed that the catalysts tend to grow on?222?and?222?crystal surfaces with high catalytic activity.The products were analyzed to find that the main product was ethanol.After 7 h,the yield was 195.78?mol·L^-1·cm^-2 with the applied voltage-1.6 V?vs SCE?and the selectivity to ethanol was 72.67%.The critical factor affecting of electrocatalysis is electron transfer,then the precious metal Au was deposited to the electrode surface to increase the electron transfer rate.Au nanoparticles were deposited by galvanostatic deposition method.The surface morphology of the electrode was detected by SEM,and the Au nanoparticles were spherical flower.The Au particles were uniformly distributed on the surface of the catalyst by EDS element distribution.By analyzing the products,after 7 h of reaction,the content of ethanol produced by the electrode modified with Au nanoparticles reached 284.12 mol·L^-1·cm^-2 with the applied voltage-1.6 V?vs SCE?,which was 31.10%higher than that of the catalyst of Sc₂O₃NPs alone(195.78 mol·L^-1·cm^-2).The amount of methanol produced was(172.25 mol·L^-1·cm^-2),which was 2.34 times higher than that of the Sc₂O₃ NPs catalyst alone(73.64 mol·L^-1·cm^-2).The selectivity of the catalyst to ethanol was reduced to 56.21%,and the selectivity to methanol was increased to 43.79%,indicating that the Au particles modified catalyst improved the selectivity to methanol and made the product more favorable for methanol.Pb metal particles were deposited on the Au-modified Sc₂O₃ NPs catalyst by pulse deposition method,and the products of the catalyst were detected as ethanol and methanol.After 7 h of reaction,the content of ethanol was 275.56 mol·L^-1·cm^-2.After the modification of Pb particles,the content of ethanol was only slightly reduced,while the content of methanol was greatly improved.The amount of methanol was 658.66 mol·L^-1·cm^-2,which was 3.8 times higher than that of Au-modified Sc₂O₃ NPs catalyst(172.25 mol·L^-1·cm^-2)and 9 times than that of the Sc₂O₃ NPs catalyst(73.64 mol·L^-1·cm^-2)alone.The selectivity of the electrode material to ethanol was29.50%and that to methanol was as high as 70.50%.In summary,the modified of metal particle not only affects the yield,but also affects the selectivity of the product.This study provides a theoretical reference for the electrocatalytic reduction of CO₂.