Efficient Z-scheme Photocatalysts of Ultrathin g-C3N4-wrapped Au/TiO2-Nanocrystals for Enhanced Visible-Light-Driven Conversion of CO2 with H2O

Abstract Z-scheme-type photocatalysts with two photochemical systems of graphic-C3N4 (g-C3N4) and anatase TiO2 (A-TiO2) nanocrystals combined with Au nanoparticles (NPs) [(Au/A-TiO2)@g-C3N4] were successfully fabricated. The surface heterojunction between coexposed {001} and {101} facets in A-TiO2 nanocrystals improves separation efficiency of photoelectrons and holes. Supported Au NPs gather and transfer the stimulated electrons originated from A-TiO2 to g-C3N4. Wrapped g-C3N4 nanosheets can not only trap the photoelectrons, but also its surface π bond can improve adsorption capabilities for CO2. (Au/A-TiO2)@g-C3N4 catalysts with enriched surface photoelectrons and CO2 exhibit high photocatalytic activity for visible-light-driven conversion of CO2, i.e., the formation rates of CH4 and CO over (Au/A-TiO2)@C3N4-5 catalyst are 37.4 and 21.7 μmol g-1 h-1, respectively. The selectivity for CO2 reduction is higher than 99 %, and the selectivity of CH4 product increases from 1.4% to 63.3 %. The innovation of Z-scheme-type photocatalysts is expected to provide new inspiration for artificial simulation photosynthesis.