Precision engineering of Z-scheme interfacial charge transfer in CoPc/Bi₂WO₆ through W-based bonds and internal electric field for efficient CO₂ photoreduction

The Z-scheme heterojunction offers hope for CO₂ reduction due to its unique charge migration, superior separation, and high redox capacity. Yet, regulating charge transfer in nanoscale heterostructure interfaces remains a significant challenge. Herein, we systematically engineered interfacial dual tungsten (W) bonds and built-in electric field (BIEF) modulated Z-scheme heterostructure composed by CoPc and Bi₂WO₆ (BWO), stimulate a Z-scheme charge shuttle cascade, channelling electrons from BWO to CoPc, thereby optimizing charge separation and upholding a high redox potential. The optimized photocatalyst exhibits high CH₄/CO₂ rate of ∼2.5 compared to pure BWO under vis-light for efficient CO₂ reduction. The improved photoactivity is confirmed through theoretical/experimental evidence, highlighting the significance of newly formed W-O-C and W-Co bonds and BIEF. These components function as atomic-level interfacial channels, efficiently accelerating Z-scheme interfacial electron shuttle and shortening the electron-shuttle distance. Furthermore, the extended visible-light range, enabled by the molecular dispersion of CoPc, and the favourable catalytic function of its central metal cation (Co²⁺) for CO₂ activation, significantly contribute to the overall enhancement. This work offers a new platform to design emerging modulated CO₂ photoreduction systems based on Z-scheme charge shuttle by regulating atomic-level interface and BIEF to remarkably encourage photocatalytic CO₂ photo-reduction performance.