Construction of sandwich-like Ag/UiO-66@g-C3N4 Z-scheme ternary heterojunction for photocatalytic CO2 conversion to CH3OH and CO

Photocatalysis technology to convert CO2 into fuels is considered as one promising strategy to mitigate the greenhouse effect and energy crisis. Herein, the Z-scheme Ag/UiO-66@g-C3N4 (AUiO@CN) composites exhibit an improved CO2 photoreduction activity owing to the increased specific surface area, strong redox capacity, rapid separation of photoinduced h+/e− pairs and fast transfer of e− at the interface. As a result, CH3OH and CO evolution rates of AUiO@CN composite are roughly 3.09 and 2.40 times higher than those of g-C3N4, respectively. The Quantum yield (QY) of CO and CH3OH for AUiO@CN are 0.0217 % and 0.0986 %. The ESR characterization and a series of electrochemical results confirmed the Ag NPs acted as e− mediator, which could promote the photogenerated charge separation and transport and CO2 reduction ability. This work not only provides a simple photo-deposition assisted grinding calcination method to prepare ternary composites, but also shows that the prepared ternary heterojunction photocatalyst can realize an efficient photocatalytic CO2 conversion to methanol and CO.