Atomic-scale facet-defect coupling enables spatially confined electron accumulation in ZnIn(2)S(4) for reductive photocatalysis.

Preferentially exposing high-index {102} facets in ZnIn2S4 couples lower sulfur-vacancy formation energy with a more negative conduction band minimum, enabling spatially confined, long-lived electron accumulation.

• Why it matters: Highly reductive photogenerated electrons tend to recombine quickly and delocalize, and prior facet engineering and defect modulation have not clarified how their synergy governs electron accumulation and kinetics.
• What they did: Density functional theory compared {102} versus {110} facets, and an ethanol-glycerol-mediated solvothermal method stabilized {102} facets; crystallographic, spectroscopic, and ultrafast transient absorption tracked sulfur vacancies and carrier lifetimes.
• The result: Facet-induced sulfur vacancies function as long-lived electron-trapping centers that promote localization, suppress recombination, and prolong carrier lifetime, yielding substantially enhanced activity in H2O2 photosynthesis, H2 evolution, Cr(VI)/U(VI) reduction, and perfluoroalkyl substance defluorination.