Study On Catalytic Reduction Of CO₂ By Bi-based Composites With Photo-Thermal Synergetic Effects

The fossil fuel what human needed for production and life has increased dramatically with the rapid development of economic,the large-scale use of fossil fuels will cause a large amount of carbon dioxide(CO2)and other greenhouse gases to be emitted,which will lead to energy shortages and the greenhouse effect.At present,the catalytic reduction of carbon dioxide by photothermal syner gistic catalytic can effectively convert carbon dioxide into carbon monoxide,methane and other renewable energy fuels,and it is also an effective way to alleviate the greenhouse effect.In this paper,the preparation of Bi/Bi2O3-x and 0.93%-Bi/RuO2 and the photothermal catalytic reduction of CO2 performance was studied based on metal bismuth.We concentrate our study on preparation,structure and photothermal synergistic catalytic reduction of CO2 of these composites by X-ray diffraction,SEM,TEM,Fourier Transform Infrared and the measurements of photocatalytic activities.The main research of this article can be summarized as the following two points:Here,cost-effective Bi/Bi2O3-x with oxygen vacancies was formed in situ on commercial bismuth powder by calcination at 453.15 K in atmosphere.SEM images are found that the sample is comprised of microspheres with diameters ranging between 20 μm to 80 μm.Interestingly,defects introduced into Bi/Bi2O3-x simultaneously induced a localized surface plasmon resonance(LSPR)in the wavelength range of 600-1400 nm and enhanced the adsorption for CO2 molecules,which enabled efficient photocatalysis of CO2-to-CO(～100%selectivity)even under low-intensity near-IR light irradiation.Significantly,the apparent quantum yield for CO evolution at 940 nm reached 0.113%,which is approximately 4.0 times that found at 450 nm.We also showed that the unique LSPR allows for the realization of a nearly linear dependence of photocatalytic CO production rate on light intensity and operating temperature.Finally,based on an IR spectroscopy study,an oxygen-vacancy induced Mars-van Krevlen mechanism was proposed to understand the CO2 reduction reactions.Bi/RuO2 composites with different amount ruthenium(Ru)were fabricated by a simple impregnation reduction method.And the Ru content in the Bi/RuO2 catalyst is 0.1-2%,and the UV-Vis-NIR test shows that the absorption edge of the photocatalyst is 1400 nm.From the SEM images and mapping test results of the sample,it can be seen that the ruthenium is uniformly dispersed on the surface of the metallic bismuth microspheres.The results of photothermal reduction of CO2 show that metal ruthenium has the best performance when the content of Bi/RuO2 is 0.93%.The average yield of carbon monoxide could reach to 28.12 μmol·g-1·h-1 at 473.15 K and 420 nm of LED light irradiation,which was 5.88 times of metallic Bi.This is mainly due to the fact that 0.93%-Bi/RuO2 had the high charge separation efficiency and the least charge transfer resistance.Moreover,the specific surface area of the material had been significantly increased,which can provide more sites for carbon dioxide adsorption to improve the activity of the photocatalyst.