Noble-Metal-Free CdS Decorated Porous Ni_xCo_1–xO Skeleton Derived from Metal–Organic Framework for Efficient Visible-Light H₂ Production

Noble-metal-free CdS@NixCo1–xO photocatalyst was synthesized for the first time using a metal–organic framework (MOF) to serve as the template for efficient visible-light photocatalytic H2 production. The entire preparation process mainly involved the calcination of NiCo-MOF and subsequent decoration of CdS nanoparticles (NPs) via hydrothermal treatment. The photoelectrical properties of pristine NixCo1–xO are optimized. With the introduction of CdS NPs, the H2 production of CdS@NixCo1–xO under visible light irradiation (λ > 420 nm) increased significantly from 0 to 2795.6 μmol g–1 h–1, thereby indicating an excellent synergistic effect between CdS and the NixCo1–xO skeleton. The band gap of CdS in the CdS@NixCo1–xO samples can be narrowed to ca. 1.54 eV. Compared with NixCo1–xO, CdS@NixCo1–xO presents an enhanced electron paramagnetic resonance (EPR) peak and low photoluminescence (PL) spectrum, directly proving its excellent charge carriers separation ability. Besides, the large specific surface area (703.27 m2 g–1) and mesoporous structure (ca. 3–4.5 nm in diameter) of CdS@NixCo1–xO can expose more active sites and serve as channels for the access of reactants, accelerating the water-cracking reduction reaction also. Furthermore, the H2 evolution performances of CdS@NixCo1–xO under visible light (λ > 400 nm) and full spectrum light are studied as well. On the basis of experiment and density functional theory (DFT) calculation results, a feasible mechanism is tentatively proposed. This work suggests the great application prospects of NiCo-MOF-based hybrid in water splitting.