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 μmol g⁻¹ _catalyst over 8 hours of visible light illumination, which is superior to the Bi₂WO₆ standalone.