Energy Platform for Directed Charge Transfer in the Cascade Z‐Scheme Heterojunction: CO2 Photoreduction without a Cocatalyst

A universal strategy is developed to construct a cascade Z‐Scheme system, in which an effective energy platform is the core to direct charge transfer and separation, blocking the unexpected type‐II charge transfer pathway. The dimension‐matched (001)TiO2‐g‐C3N4/BiVO4 nanosheet heterojunction (T‐CN/BVNS) is the first such model. The optimized cascade Z‐Scheme exhibits ≈19‐fold photoactivity improvement for CO2 reduction to CO in the absence of cocatalysts and costly sacrificial agents under visible‐light irradiation, compared with BVNS, which is also superior to other reported Z‐Scheme systems even with noble metals as mediators. The experimental results and DFT calculations based on van der Waals structural models on the ultrafast timescale reveal that the introduced T as the platform prolongs the lifetimes of spatially separated electrons and holes and does not compromise their reduction and oxidation potentials. A cascade Z‐Scheme system composed of a dimension‐matched (001)TiO2‐g‐C3N4/BiVO4 heterojunction is proposed, in which the energy platform (001)TiO2 is used to direct charge transfer and separation, thus blocking the unexpected type‐II charge transfer pathway. The role of TiO2 is thus not only to facilitate the Z‐Scheme charge transfer but also to maintain the strong redox potentials for CO2 photoreduction and water splitting.