Preparation And Photothermal Catalytic Activity Of Iron-based Perovskite For CO₂ Reduction

The concentration of pollutants in the atmosphere was increasing with the rapid development of modern industry.Carbon dioxide as the main gas source of greenhouse effect leading to rising global temperatures has resulted in a series of environmental problems which were widely concerned by mankind.Many scholars in the world racked their brains about how to solve this problem.For conventional physical treatment method,a more environmentally robust and promising solution is convert CO₂ into new energy that can be recycled again by using chemical methods.In this paper,base on lanthanum ferrite material,the LaCo_x Fe_1-x-x O₃?x=0,0.2,0.4,0.6,0.8?nanopowders with different doped ratio were prepared using sol-gel method by doping transition metal element cobalt in B site,the crystal structure,microstructure,specific surface area,oxygen vacancy,band structure and catalytic performance were characterized in detail.Under the conditions of photothermal and thermal conditions?350?+vis-light?for 6 hours.the experimental results show that the average yield of CH₄ and CH₃OH can reach 361.01 and 72.04?mol g^-1 respectively,the yield increased by 3.0 and 4.8 times respectively compared with LaFeO₃ perovskite with no Co-doping.This is mainly due to the doping elements has a certain influence on t he band structure of the sample,which makes the dopant material has great application prospects in photothermal reduction of CO₂ to hydrocarbon fuel.Based on the development of lanthanum ferrite,doped with another transition metal element Ni in B-site,the LaNi_x Fe_1-xO₃ nanopowders using the sol-gel method were investigated by using XRD,SEM,TEM,BET and UV-vis characterization methods and focusing on its catalytic activity.The results show that when the doping amount of Ni is0.4,the sample exhibits the best photothermal catalytic performance.Under the same catalytic conditions,the LaNi_x Fe_1-x-x O₃ obtained average maximum methane and methanol levels of 383.02 and 76.27?molg^-1 after 6 hours with visible light irradiation.In this study,The effects of doping on the band gap of the sample were investigated,it was found that different doping elements and proportion has a certain regularity in adjusting the band structure of the sample,which increase the catalytic activity due to reduce the band gap and optimize the position of the conduction band and valence band.Finally,the specific effects of three different elements and different doping ratios on the photocatalytic performance were investigated by the doping of cobalt and nickel based on the ternary phase diagram of three adjacent elements of iron,cobalt and nickel.We successfully synthesized LaCo_x Fe_1-x-x O₃?x=0,0.2,0.4,0.6,0.8,1?nanoparticles using the sol-gel process and depth study of its band structure.The experimental results show that the doping between different transition metal elements has a certain influence on the catalytic activity of the material.Finally,it found that the average yield of methane and methanol were 493.14 and 92.43?molg^-1 respectively by a series of experiments at the best combination of cobalt and nickel,the best catalytic performance can be obtain by finding the most suitable combination of elements.In addition,a new method has been developed by combining the optical,thermal and chemical processes in this paper,which reduction CO₂ to hydrocarbon fuels to optimize its photocatalytic properties.