Preparation And Photocatalytic CO₂ Reduction Performance Of BiOBr/Fe_xO_y@ACSs Catalyst

Photocatalytic reduction of CO₂ using solar energy to decrease CO₂ emission is a promising clean renewable fuel production technology.Recently,Bi-based semiconductors with excellent photocatalytic activity and carbon-based carriers with large specific surface area and strong CO₂ adsorption capacity have attracted extensive attentions.However,for a single BiOBr photocatalyst,there existed the low separation efficiency of electron-hole pairs and the weak CO₂ adsorption capacity limiting its development and application in the photocatalytic CO₂reduction.Therefore,it is urgent for us to construct an ideal photocatalyst system with excellent light absorption,efficient separation of photogenerated e^--h⁺pairs and high CO₂ adsorption capacity.According to above-mentioned problems,the selection of materials with the higher adsorption capacity and larger specific surface area as well as stronger charge transfer ability to load high-efficiency photocatalysts should be very significant and interesting issues about the research and development of photocatalytic CO₂ reduction.?1?In this work,activated carbon spheres?ACSs?were obtained via carbonization and steam activation at 850°C through as-synthesized phenolic resin-based carbon spheres by suspension polymerization.Then,BiOBr/ACSs sample was successfully prepared via a simple impregnation method.As-prepared samples were characterized by XRD,SEM,EDX,DRS,PL,EIS,XPS,BET,CO₂adsorption isotherm and CO₂-TPD.BiOBr and BiOBr/ACSs samples exhibited the high CO selectivity for photocatalytic CO₂ reduction,and BiOBr/ACSs achieved rather higher photocatalytic activity(23.74?mol·g^-1·h^-1)than one of BiOBr(2.39?mol·g^-1·h^-1)under simulated sunlight irradiation.Moreover,analysis results indicate that,for such photocatalyst system,the higher micropore surface area and larger micropore volume of ACSs provide enough physical adsorption sites for CO₂ adsorption step,and the intrinsic structure of ACSs could offer the effective electron transfer ability for a fast-efficient separation of photo-induced electron-hole pairs.Finally,a possible enhanced photocatalytic mechanism of BiOBr/ACSs was investigated and proposed.Our findings should provide new and important research ideas for the construction on the high-efficient photocatalyst system of CO₂ reduction to solar fuels and chemicals.?2?Fe_xO_y@ACSs were successfully prepared by adding Fe salt during the preparation of ACSs and simultaneously undergoing high temperature carbonization and steam activation.Then,BiOBr/Fe_xO_y@ACSs samples were prepared by a simple impregnation method.It was found by XRD analysis that Fe element exists in ACSs in the form of Fe₂O₃ and Fe₃O₄.Photocatalytic experiments showed that BiOBr/Fe_xO_y@ACSs had higher photocatalytic activity,and the corresponding rate was 43.85?mol·g^-1h^-1.After a series of characterization analysis,the enhanced photocatalytic activity is attributed to the existence of Fe,which will cause the interface charge transfer effect,so that the charge can be transferred more quickly and the recombination of photogenic e^--h⁺pairs can be avoided.In addition,the remarkable light absorption properties of Fe_xO_y@ACSs improve the absorption of BiOBr in the visible region.The stronger CO₂ adsorption capacity of Fe_xO_y@ACSs makes the BiOBr supported on the surface in a CO₂-enriched environment,which is more conducive to the photoreaction of e^-and CO₂.Finally,the possible photocatalytic mechanism of BiOBr/Fe_xO_y@ACSs samples was proposed.