In Situ Fabrication of NiS₂‑Decorated\nGraphitic Carbon Nitride/Metal–Organic Framework Nanostructures\nfor Photocatalytic H₂ Evolution

Abstract

Photocatalytic\nwater splitting for hydrogen production is an effective\nway to solve energy crisis. However, the challenge of how to solve\nthe problem of short exciton lifetime of the catalyst still remains.\nIn this work, a g-C₃N₄/UNiMOF/NiS₂ (GUN) ternary heterojunction (TH) has been successfully constructed\nusing two-dimensional (2D) UNiMOF as a precursor by the partial hydrothermal\nsulfidation method. As expected, the optimized GUN-40 heterojunction\ncontaining 40 mg of UNiMOF (GUN-40) exhibited higher H₂ evolution (572 μmol h^–1 g^–1) and a longer exciton recombination lifetime (τ = 12.12 ns)\nthan those of pure g-C₃N₄ (0.67 μmol h^–1 g^–1, 7.87 ns) under visible light.\nIn addition, the apparent quantum yield (AQY) of GUN-40 was up to\n1.54 % at 450 nm. Apparently, the GUN TH structure effectively promotes\nelectron transfer to the NiS₂ active site, allowing a long\nrecombination lifetime, and reduces the probability of recombination\nof electron holes, thus obviously improving photocatalytic efficiency.\nThis work provides insights into the preparation of a cocatalyst using\n2D MOF as a template and construction of the TH structure with good\ncharge separation for efficient photocatalysis.