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

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.