Noble-metal-free CdS/Ni-MOF composites with highly efficient charge separation for photocatalytic H2 evolution

Constructing semiconductor-based photocatalysts with high-performance and excellent stability is a promising approach to achieve optimum photocatalytic H2 production rate from water splitting. In this study, a novel effective visible-light-driven catalyst, namely, CdS/Ni-MOF, has been successfully synthesized by in-situ growth of CdS nanoparticles on the surface of hollow Ni-based metal-organic framework (Ni-MOF) spheres. The heterogeneous interface contact and matched band position promote charge separation. As a noble-metal-free catalyst, the obtained CdS/Ni-MOF composite having an optimal CdS loading of 40 wt.% exhibits a remarkable H2 production rate of 2508 μmol/g/h under visible light, which is about eight times higher than that of single CdS. Ni-MOF serves as a station for the rapid transfer of photo-induced electrons, leading to the high photocatalytic performance. Meanwhile, Ni-MOF comprising highly dispersed Ni2+ catalytic sites also acts as co-catalyst, which is beneficial for hydrogen evolution. Therefore, Ni-MOF functions as both an electron acceptor and a co-catalyst in the photocatalytic H2 production from water. This work highlights the advantages of combining semiconductor and MOF functionalities to fabricate a photocatalyst with enhanced catalytic activity.