Construction of S-scheme Co₃O₄/g-C₃N₄ heterojunctions with boosted photocatalytic H₂ production performance

The key step of photocatalytic technology using light energy to split water for hydrogen production is to prepare high performance and environmentally friendly stable photocatalysts. In this study, Co3O4 was loaded onto polymeric carbon nitride (PCN) to construct S-scheme heterojunctions by an impregnating method. The successful construction of S-scheme Co3O4/PCN heterojunctions was proved by the various characterizations, the constructed S-scheme Co3O4/PCN heterojunctions have favorable photoelectric effect and exhibit better H-2 evolution performance than the single Co3O4 and PCN. Construction of S-scheme Co3O4/PCN heterojunctions can elevate active sites induced by N-deficient formation. Therein, 3% is the optimal molar ratio of Co/PCN, and the corresponding sample (3CoO/CN) exhibits the highest H-2 evolution efficiency (105.06 mu mol.g(-1).h(-1)) via simulated solar light illumination for 4 h, which is about 41 folds higher than the single PCN (2.48 mu mol.g(-1).h(-1)). In short, the conspicuously boosted water splitting efficiency is mainly due to the strong light responsiveness and rapidly separation and migration of photoexcited charge pairs. The cyclic experiment results show that the Sscheme Co3O4/PCN heterojunction photocatalysts have high stability. The apparent quantum efficiency (AQE) of H-2 generation on 3CoO/CN is 0.053% under 420 nm monochromatic light irradiation. This study strongly verifies that construction of S-scheme Co3O4/PCN heterojunctions is a feasible route to boost the photocatalytic activity of g-C3N4, providing an interesting reference for design highly efficient and environmentally friendly C3N4-based photocatalysts.