Theoretical and experimental studies of highly efficient all-solid Z-scheme TiO2–TiC/g-C3N4 for photocatalytic CO2 reduction via dry reforming of methane

摘要

An all-solid Z-scheme heterojunction TiO2–TiC/g-C3N4 was proposed and synthesized successfully by a facile calcination method and used for photocatalytic CO2 reduction in the presence of CH4. Under sub-atmospheric pressure and at room temperature, the Z-scheme heterojunction TiO2–TiC/g-C3N4 presented enhanced photocatalytic performance compared to g-C3N4, TiO2–TiC and TiO2/g-C3N4. Both in situ XPS results and DFT calculations results verified the formation of the Z-scheme heterojunction. The theoretical calculations showed that TiC acts as an electron mediator in which the electrons from the conduction band (CB) of TiO2 recombine with the holes in the valence band (VB) of g-C3N4. Therefore, higher redox potentials are preserved, achieving high photocatalytic reaction efficiency. Besides, the DFT calculations established a stable TiO2–TiC/g-C3N4 model. Orthogonal experiments were carried out to explore the optimal conditions, and under optimal conditions the TOF of CO and H2 reached 11.3 μmol g−1 h−1 and 2.15 μmol g−1 h−1, respectively.