Achieving Direct Z‑Scheme Charge Transfer through Constructing 2D/2D α‑Fe2O3/CdS Heterostructure for Efficient Photocatalytic CO2 Conversion

Heterostructure construction is an effective performance regulation method for photocatalytic field, while its application in solar-driven CO2 conversion is highly restricted by inevitably sacrificing the stronger redox ability of photoinduced charges. Herein, a well-designed α-Fe2O3@CdS bilayer heterostructure with ultrathin two-dimensional (2D) shape and sufficient interface contact is deliberately constructed by a two-step solvothermal method. Effective interfacial electronic coupling as well as highly enhanced photoinduced charge separation and elongated photoelectron lifetime are implemented in this nanohybrid. Such 2D/2D heterostructure exhibits much more efficient photocatalytic CO2 conversion than bare CdS and α-Fe2O3. The direct Z-scheme charge transfer path and dynamics achieved by favorable internal built-in electric field (IEF) at heterointerface mainly contribute to the excellent photocatalytic CO2 reduction performance. The evident work function difference as well as the large heterointerface area and short carrier diffusion distance to interface between 2D CdS and 2D α-Fe2O3 contribute to the favorable IEF. This work provides a deep understanding of the construction and interface electronic mechanism of the direct Z-scheme heterostructure for application in future solar energy conversion.