In Situ Fabrication of NiS₂-Decorated Graphitic Carbon Nitride/Metal–Organic Framework Nanostructures for Photocatalytic H₂ Evolution

Photocatalytic water splitting for hydrogen production is an effective way to solve energy crisis. However, the challenge of how to solve the problem of short exciton lifetime of the catalyst still remains. In this work, a g-C3N4/UNiMOF/NiS2 (GUN) ternary heterojunction (TH) has been successfully constructed using two-dimensional (2D) UNiMOF as a precursor by the partial hydrothermal sulfidation method. As expected, the optimized GUN-40 heterojunction containing 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) than those of pure g-C3N4 (0.67 μmol h–1 g–1, 7.87 ns) under visible light. In addition, the apparent quantum yield (AQY) of GUN-40 was up to 1.54 % at 450 nm. Apparently, the GUN TH structure effectively promotes electron transfer to the NiS2 active site, allowing a long recombination lifetime, and reduces the probability of recombination of electron holes, thus obviously improving photocatalytic efficiency. This work provides insights into the preparation of a cocatalyst using 2D MOF as a template and construction of the TH structure with good charge separation for efficient photocatalysis.