Preparation And Photocatalytic CO₂ Reduction Performance Of In₂O₃-based Complexes Rich In Oxygen Vacancies

As a wide-band gap n-type semiconductor,indium oxide(In₂O₃)has a good application prospect in photocatalytic CO₂reduction due to its suitable band structure,unique chemical stability,and relatively high CO₂adsorption capacity.Nevertheless,traditional In₂O₃photocatalysts materials still have disadvantages such as poor selectivity,low reactivity,poor light absorption,and low charge separation efficiency.This severely limits the large-scale application of In₂O₃photocatalysts.In view of the existing problems of In₂O₃photocatalyst,In₂O₃was modified in this study by combining the introduction of oxygen vacancy with the construction of heterojunction structure,co-catalyst modification and morphology control,which improved the visible light utilization rate,CO₂adsorption capacity and photogenerated charge separation and transmission efficiency of the material,leading to significntly enhanced photocatalytic CO₂reduction activity and selectivity.The main content of the paper is as follows:(1)Hollow hexagonal In₂O₃-CeO₂catalysts doped with S and coated with C were prepared.The oxygen vacancy concentration in S-C/In₂O₃-CeO₂samples was adjusted by doping S powder during calcination.The formation of heterojunction,the doping of S,the introduction of oxygen vacancy and the formation of carbon coating promoted the effective separation of charge carriers,light absorption and CO₂absorption of the photocatalyst.Under the synergistic effects of these factors,the efficient gaseous phase photocatalytic reduction of CO₂was achieved with a CH₄yield of 60.6?mol g^-1h^-1and 92.4%selectivity.(2)Vo-In₂O₃-SnS₂heterojunction photocatalyst was designed and prepared.The introduction of oxygen vacancies and the formation of a unique 2D-2D heterojunction structure improve the light absorption and the efficiency of photogenerated charge transfer separation.The effect of SnS₂loading on photocatalyst performance was also studied.When the loading amount of SnS₂is 10%,Vo-In₂O₃-SnS₂has the highest activity and selectivity in photocatalytic CO₂reduction with a CO yield of 85.19?mol g^-1h^-1and 78%selectivity.(3)Co₃O₄cocatalyst decorated Nitrogen-doped In₂O₃with oxygen vacancies(N-In₂O₃-Co₃O₄)was synthesized by two-step pyrolysis using Co-In-ZMOF as precursor.The synthesized N-In₂O₃-Co₃O₄has a unique hollow porous dodecahedron shape.The synergistic effects of N doping,abundant surface oxygen vacancies,and proper amount of cocatalyst modification accelerated the charge transfer rate,increased the light absorption,and improved the reaction selectivity.The photocatalytic CO₂reduction activity of N-In₂O₃-Co₃O₄is significantly improved.The CO yield of N-In₂O₃-Co₃O₄is 4 times that of pure In₂O₃.