Chlorella-assisted enhancement of photocatalytic hydrogen evolution over ZnIn₂S₄ from Water Splitting

Modulating the electronic structure of inorganic semiconductors using biomass is an emerging strategy for developing highly efficient photocatalysts. In this study, Chlorella (Ch) was used as a biological carrier and electron donor, and a bio-inorganic hybrid photocatalyst, Chlorella@ZnIn₂S₄ (ZIS-Ch), featuring bio-induced sulfur vacancy formation, was successfully synthesized via a one-step hydrothermal method. Experimental and characterization results indicate that nitrogen- and oxygen-containing functional groups (–NH 2 , –OH, –COOH) on the Ch surface form interfacial covalent bonds (M–N/O) with Zn 2+ /In 3+ in ZnIn₂S₄, inducing the directed injection of electrons from Ch into the ZnIn 2 S 4 lattice. Concurrently, EPR spectroscopy detected the formation of sulfur vacancies (V S ). Under simulated sunlight and under optimal conditions, the photocatalytic hydrogen production rate of ZIS-Ch40 reached [7.969 mmol⋅g −1 ⋅h −1 ], which is 1.59 times and 5.6 times higher than that of pure ZIS and Ch, respectively, and it maintained good activity even after five cycles. This study provides a new approach for utilizing intact cells to regulate inorganic semiconductor defects and band structures, thereby enabling highly efficient solar hydrogen production.