Fabrication of Bi2WO6/Cu/WO3 All-Solid-State Z-Scheme Composite Photocatalyst to Improve CO2 Photoreduction under Visible Light Irradiation

Photocatalysis has been widely explored to alleviate the high atmospheric CO2 content by converting CO2 into energy-rich fuels. Bi2WO6 shows great potential in photocatalysis due to its high chemical stability, non-toxicity and appropriate band position. However, the CH4 yield from CO2 photoreduction over bulk Bi2WO6 is relatively low ascribed to its single-component structure. Inspired by natural photosynthesis, Z-scheme system with photosystem I (PS I)-photosystem II (PS II) coupling via an electron mediator can improve charge separation and at the same time, renders large overpotential, attributed to the vectorial electron transfer from PS II to PS I. In this contribution, an all-solid-state Z-scheme photocatalyst that is composed of 2D Bi2WO6 nanosheets coupled with WO3 along with the incorporation of copper foil sheet as the electron mediator is designed to improve the CO2 reduction efficiency. The Bi2WO6/Cu/WO3 composite demonstrated a remarkable CH4 yield of 8.80 mu mol g(catalyst)(-1) over 8 hours of visible light illumination, which is superior to the Bi2WO6 standalone.