Insight into NiCo-based nanosheets modified MnS/Mn0·2Cd0·8S hybrids for enhanced visible-light photocatalytic H2 evolution

Bimetallic compounds nanocrystals exhibited great potential in catalysis due to the synergistic effects and encouraging performance. Herein, a series of NiCo-based nanosheets, including NiCo LDH/NiCo(OH)₂, NiCo, and NiCo₂O₄, have been developed to modify MnS/Mn_0·2Cd_0·8S (MMCS) nanoparticles for photocatalytic H₂ production under visible light (λ > 420 nm). The two-dimensional (2D) NiCo₂O₄ and NiCo were derived from the oxidation and reduction process of the as-prepared NiCo LDH/NiCo(OH)₂ nanosheets, respectively. MMCS nanoparticles were prepared using a one-pot solvothermal method and then integrated into three different NiCo-based nanosheets through a simple hybridization approach. Compared to pure MMCS, the resultant NiCo-based nanosheets/MMCS hybrids show dramatically improved visible-light photocatalytic activities. Moreover, among the three types of composites, NiCo₂O₄-MMCS (7%NiCo₂O₄-MMCS) displays the highest H₂ production rate of 3.31 mmol g^?1 h^?1 with the apparent quantum efficiency of 6.42% at 420 nm, approximately 22 and 5 times that of pure MMCS (0.15 mmol g^?1 h^?1) and Pt/MMCS (0.67 mmol g^?1 h^?1), respectively. The remarkably enhanced photocatalytic activities of the NiCo LDH/NiCo(OH)₂-MMCS, NiCo-MMCS, and NiCo₂O₄-MMCS are mainly ascribed to the formed type-II, Schottky, and p-n heterojunctions, respectively, which efficiently boost photogenerated charge carrier separation and migration. In this paper, we intensively investigate the roles of three different NiCo-based nanosheets in the Mn_xCd_1-xS-based system. This work provides an effective strategy to design and construct the innovative 2D bimetallic compounds-based catalysts for high-efficiency photocatalytic H₂ production.