Efficient suppression of charge recombination remains a central challenge in photocatalytic CO 2 reduction. Here, we report a rational source‐to‐design strategy to construct both direct and indirect Z‐scheme heterojunctions by integrating graphitic carbon nitride ( g ‐C 3 N 4 ), bismuth oxyiodide (BiOI), and Ag nanoparticles. A solvent‐free ball‐milling process combined with light‐driven Ag photodeposition enables intimate interfacial coupling while preserving the layered frameworks of both semiconductors. Among the resulting systems, the Ag‐bridged indirect Z‐scheme exhibits a CO evolution yield of 344.6 μmol g −1 under visible‐light irradiation, markedly outperforming pristine g ‐C 3 N 4 and the direct Z‐scheme counterpart. Mechanistic investigations reveal that Ag nanoparticles function as efficient electron mediators, facilitating directional electron transfer from BiOI to Ag and hole transfer from g ‐C 3 N 4 to Ag, thereby suppressing recombination and enhancing carrier mobility. This work establishes an effective design paradigm for indirect Z‐scheme photocatalysts and provides general insights into mediator‐assisted interfacial engineering for solar‐driven CO 2 conversion.
Tsai et al. (Tue,) studied this question.