In Situ Confined Growth of Co3O4–TiO2/C S-Scheme Nanoparticle Heterojunction for Boosted Photocatalytic CO2 Reduction

Abstract

An S-scheme nanoparticle heterojunction of Co₃O₄–TiO₂/C has been designed to enhance CO₂ adsorption and accelerate interfacial electron transfer, thereby boosting photocatalytic CO₂ reduction. Co²⁺-loaded MXene nanosheets are used as a single precursor for in situ confined growth of Co₃O₄–TiO₂/C. The in situ confined growth of the nanoparticle heterojunction enables good particle dispersion and a small particle size, which makes the surface and active sites highly exposed and accessible for CO₂ molecules. In addition, p-type Co₃O₄ and n-type TiO₂ build an S-scheme heterojunction. As a result, the Co₃O₄–TiO₂/C nanoparticle heterojunction exhibits a higher specific surface area, larger CO₂ adsorption capacity, and faster charge transfer compared to pure Co₃O₄ and TiO₂/C. The gas generation rate over Co₃O₄–TiO₂/C is as high as 33.21 mmol g^–1 h^–1, which is 8.34 and 1.69 times higher than that of pure TiO₂/C and Co₃O₄, respectively. 3 h photocatalysis affords a remarkable turnover number of 15.53 that is comparable to state-of-the-art photocatalysts.