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

Van der Waals (vdW) heterojunctions enhance photocatalyst efficiency but face electron transfer challenges at component interfaces due to large spacing and potential barriers. We introduce a novel wet chemistry approach to enhance the efficiency of photocatalysts by creating a functionalized graphene-modulated Z-scheme vdW heterojunction (xZnPc/yG-WO3) to eliminate interfacial potential differences, enabling better electron transfer for improved photocatalytic reactions and molecular dispersion. [Display omitted] 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.