Enhancement in photocatalytic activity of CO2 reduction to CH4 by 0D/2D Au/TiO2 plasmon heterojunction

Abstract Photocatalytic CO 2 reduction is considered as an efficient approach to reduce greenhouse effect and overcome energy crisis. Herein, we successfully fabricated 0D/2D Au/TiO 2 plasmon Ohmic-junction composites, which exhibit excellent photocatalytic activity of CO 2 reduction to CH 4 . The main reduction products of the optimized 0D/2D Au/TiO 2 heterojunction are CH 4 and CO obtained at the rates of 70.34 and 19.75 μmol·g −1 ·h −1 , respectively, with 80% CH 4 selectivity. Transmission electron microscopy, UV–vis diffuse reflection spectra and photo-electrochemical tests along with density functional theory calculations confirm that the improved photocatalytic CO 2 reduction performance and high CH 4 selectivity are attributed to the synergistic effects between plasmonic Au NPs and Ohmic-junction of Au and TiO 2 , which can effectively enhance the separation and transportation of photo generated carriers and promote a multi-electron reduction reaction of CO 2 and H 2 O, resulting in high selectivity of CH 4 generation. These results also indicate that the Au/TiO 2 plasmon Ohmic-junction can act as a highly effective CO 2 reduction photocatalyst for future applications of energy conversion.