Noble-Metal-Free CdS Decorated Porous NixCo1-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 H-2 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 H-2 production of CdS@NixCo1-xO under visible light irradiation (lambda > 420 nm) increased significantly from 0 to 2795.6 mu mol 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 m(2) 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 H-2 evolution performances of CdS@NixCo1-xO under visible light (lambda > 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.