Heterojunction construction by a coordination bond between metal-organic frameworks and CdIn₂S₄ for improved photocatalytic performance

Photocatalytic water splitting using a semiconductor is one of the most effective ways to obtain clean energy. However, a pure semiconductor exhibits a poor photocatalytic performance because of its harsh charge carrier recombination, limited light harvesting ability and deficiency of surface reactive sites. Herein, the hydrothermal method is employed to synthesize a new UiO-66-NH2/CdIn2S4 (NU66/CIS) heterojunction nanocomposite, constructed via a coordination bond between NU66 and CIS. Benefitting from the great specific surface area, the UiO-66-NH2 provides abundant reactive sites on its surface to boost the water reduction. Moreover, the amino groups in the UiO-66-NH2 are supplied as coordination sites to establish strong interactions between NU66 and CIS, thus forming the heterojunction with intimate connections. Therefore, the electrons produced by photoexcitation of CIS can be more effectively promoted to transfer to NU66, and then react with H+ in water to produce H-2. Accordingly, the optimized 8% NU66/CIS heterojunction exhibits a considerable photocatalytic efficiency for water splitting, in which the H-2 production rate is 7.8 times higher than that of bare CIS, and 3.5 times as high as that of the two materials combined by simple physical mixing. This research offers a creative and innovative idea for the construction of active MOF-based photocatalysts for H-2 evolution.