CdMnS/Ag2W2O7 S-scheme heterojunction boosting charge separation via built-in electric field for efficient hydrogen evolution

Heterojunction engineering is an effective strategy for optimizing carrier transport pathways. In this study, a CdMnS/Ag2W2O7 S-scheme heterojunction photocatalyst was successfully constructed via a physical stirring mixing method. Under the optimal component ratio, the hydrogen evolution rate of the as-prepared CdMnS/Ag2W2O7 composite reached 4.84 mmol·h−1·g−1, corresponding to a 3.24-fold increase relative to pristine CdMnS. Additionally, it retained excellent catalytic stability throughout a 30-hour reaction period. By combining the characteristic evolution of •OH and •O2- species in EPR spectra with the shifts in elemental binding energies observed during in-situ XPS analysis, the migration of photogenerated charge carriers in this system was confirmed to follow an S-scheme mechanism. This mechanism enables photogenerated electrons with strong reduction capability to accumulate in the conduction band of CdMnS, where they actively participate in the hydrogen evolution reaction (HER), consequently boosting the hydrogen production efficiency. Experimental investigations and theoretical calculations confirmed that such a tight interfacial contact between the two components enables efficient charge separation and transfer, thereby underpinning the remarkable photocatalytic performance.