Persistent Charge‐Carrier Transfer Enables Decoupled Light and Dark Photocatalysis in ZnIn ₂ S ₄ /Phosphor Heterojunctions

Photocatalytic water splitting represents a promising approach for solar‐to‐hydrogen energy conversion. However, conventional photocatalysts suffer from solar intermittency owing to the short‐lived charge carriers. Herein, we demonstrate a heterostructure catalyst capable of decoupling light and dark reactions through persistent charge‐carrier transfer enabled by the in situ growth of ZnIn 2 S 4 (ZIS) on Sr 2 MgSi 2 O 7 :Eu 2+ ,Dy 3+ (SMSED), a long‐afterglow phosphor. Taking advantage of SMSED's ultra‐long afterglow, photogenerated electrons with lifetimes extending over several hours continuously drive hydrogen evolution even in the absence of light. The SMSED/ZIS heterojunction achieves a hydrogen evolution rate of 18.78 mmol·g −1 ·h −1 under light irradiation and sustains 8.37 mmol·g −1 of hydrogen generation over 5 h in darkness. Mechanism studies provide direct evidence of dark‐state electron transfer from SMSED to ZIS. This work offers a general strategy for rational design of highly efficient all‐weather photocatalysts that overcome solar intermittency through persistent charge storage and release.