Dimension-Matched Zinc Phthalocyanine/BiVO₄ Ultrathin Nanocomposites for CO₂ Reduction as Efficient Wide-Visible-Light-Driven Photocatalysts via a Cascade Charge Transfer

Cascade charge transfer was realized by a H-bond linked zinc phthalocyanine/BiVO₄ nanosheet (ZnPc/BVNS) composite, which subsequently works as an efficient wide-visible-light-driven photocatalyst for converting CO₂ into CO and CH₄, as shown by product analysis and ¹³C isotopic measurement. The optimized ZnPc/BVNS nanocomposite exhibits a ca. 16-fold enhancement in the quantum efficiency compared with the reported BiVO₄ nanoparticles at the excitation of 520 nm with an assistance of 660 nm photons. Experimental and theoretical results show the exceptional activities are attributed to the rapid charge separation by a cascade Z-scheme charge transfer mechanism formed by the dimension-matched ultrathin (ca. 8 nm) heterojunction nanostructure. The central Zn²⁺ in ZnPc could accept the excited electrons from the ligand and then provide a catalytic function for CO₂ reduction. This Z-scheme is also feasible for other MPc, such as FePc and CoPc, together with BVNS.