Charging dynamics engineering: Quantum dots-induced full-space electric field cooperative Ag2S QDs/CoWO₄ S-scheme heterojunction boosting photocatalytic hydrogen evolution

Quantum dots (QDs) demonstrate significant potential in the field of photocatalytic hydrogen production due to their unique photoelectronic properties. In this study, based on the successful synthesis of Ag2S QDs, a rationally designed CoWO4/Ag2S S-scheme heterojunction was constructed by utilizing the band structure and Fermi level difference between CoWO4 and Ag2S QDs. Simultaneously, an efficient full-space electric field was engineered on the Ag2S QDs-modified CoWO4 photocatalyst through charge polarization strategy. Specifically, this robust full-space electric field was formed via cascaded coupling of the bulk electric field and the interface electric field. The successful establishment of both the CoWO4/Ag2S S-scheme heterojunction and the full-space electric field was confirmed through characterization techniques including femtosecond transient absorption spectra, Kelvin probe force microscopy and in-situ X-ray photoelectron spectroscopy, along with density functional theory calculation results. Under the synergistic effect of the continuously driven full-space electric field and the S-scheme heterojunction, the separation of photogenerated electrons and holes has been significantly enhanced, enabling substantial electron accumulation on the catalyst surface for reaction participation, thereby greatly improving charge utilization efficiency. Meanwhile, it greatly facilitates the participation of highly oxidizing-reducing capable photogenerated electrons and holes in the reaction, providing sufficient driving force for the hydrogen evolution reaction. Ultimately, the hydrogen production rate of CWAS-10 reached 1546.23 μmol·g–1·h–1 within 5 h. Compared with the original CoWO4 and Ag2S, the performance was improved by nearly 2.6 and 4.2 times, respectively. This study offers a novel strategy for constructing S-scheme heterojunctions via quantum dot modification and synergistically regulating charge dynamics, providing valuable insights for the design of efficient photocatalysts in the field of energy conversion.