TiO2/MXene Ti3C2 composite with excellent photocatalytic CO2 reduction activity

Photocatalytic CO2 reduction for solar fuel production has received enormous attention due to its ability for solving both energy crisis and CO2 pollution. However, fabrication of cheap and efficient materials for photocatalytic CO2 reduction is still challenging. Herein, TiO2 nanoparticles (NPs) in situ grew on highly conductive MXene Ti3C2 through calcination method. And a unique rice crust-like structure was achieved through the uniform distribution of TiO2 nanoparticles on Ti3C2. This optimized TiO2/Ti3C2 composite exhibited a 3.7 times higher photocatalytic CO2 reduction performance for CH4-production (0.22 μmol h−1) than commercial TiO2 (P25). The detailed photocatalytic CO2 reduction mechanism using TiO2/Ti3C2 was confirmed through the 13CO2 isotopic test and in situ diffuse reflectance infrared Fourier transform spectroscopy. Experimental evidence along with preliminary calculation was also used to further elucidate the proposed photocatalytic enhancement mechanism. This extraordinary photocatalytic performance was due to the unique morphology and the features of individual components in the composite. Namely, fluffy rice crust-like structure of the prepared samples rendered the composite with large population of the surface-active sites. Ultrahigh conductivity of Ti3C2 facilitated the photogenerated electron transfer and suppressed its recombination with photogenerated holes. This work presents a simple method to prepare highly efficient TiO2/Ti3C2 composite for photoconversion applications.