Molecular modulation of interfaces in a Z-scheme van der Waals heterojunction for highly efficient photocatalytic CO₂ reduction

The construction of van der Waals (vdW) heterojunctions is a key approach for efficient and stable photocatalysts, attracting marvellous attention due to their capacity to enhance interfacial charge separation/transfer and offer reactive sites. However, when a vdW heterojunction is made through an ex-situ assembly, electron transmission faces notable obstacles at the components interface due to the substantial spacing and potential barrier. Herein, we present a novel strategy to address this challenge via wet chemistry by synthesizing a functionalized graphene-modulated Z-scheme vdW heterojunction of zinc phthalocyanine/tungsten trioxide (xZnPc/yG-WO₃). The functionalized G-modulation forms an electron “bridge” across the ZnPc/WO₃ interface to improve electron transfer, get rid of barriers, and ultimately facilitating the optimal transfer of excited photoelectrons from WO₃ to ZnPc. The Zn²⁺ in ZnPc picks up these excited photoelectrons, turning CO₂ into CO/CH₄ (42/22 μmol.g⁻¹.h⁻¹) to deliver 17-times better efficiency than pure WO₃. Therefore, the introduction of a molecular “bridge” as a means to establish an electron transfer conduit represents an innovative approach to fabricate efficient photocatalysts designed for the conversion of CO₂ into valued yields.