ZnIn₂S₄ Heterojunctions Constructed with In-MOF Precursor for Photocatalytic Hydrogen Evolution without Cocatalysts

Znln₂S₄ has great prospects for photocatalytic water splitting to hydrogen by visible light. Herein, a novel Znln₂S₄-In-MOF (ZnIn_MS₄) photocatalyst is elaborately synthesized by in situ method with In-MOF as the template and In³⁺ as the source. ZnIn_MS₄ overcomes the fast interface charge recombination and a sluggish charge lifetime via the formed heterojunctions. Photoelectrochemical measurements reveal that the charge-transfer kinetics is enhanced since In-MOF is introduced to act as a reliable charge-transport channel. ZnIn_MS₄ exhibits outstanding cocatalyst-free H₂ evolution rate of 70 μmol h^-1 under irradiation (λ > 420 nm), which is 3.2-fold higher than that of Znln₂S₄. In addition, the ZnIn_MS₄ photocatalyst shows good stability in the 16 h continuous reaction. This work illustrates the feasibility of the MOF precursor instead of inorganic salts to directly synthesize photocatalysts with high performance.