Novel ZnCdS Quantum Dots Engineering for Enhanced Visible-Light-Driven Hydrogen Evolution

Semiconducting quantum dots (QDs) engineering is considered as an effective approach to improve the light-harvesting ability of the devices for solar energy converting. Current routes for the construction of QDs from metal–organic frameworks (MOFs) always retain carbon materials to avoid particle aggregations, which could obstruct light harvesting process. Herein, novel ZnCdS QDs without carbon supporting are rationally designed and fabricated by controlled annealing and a sequential sulfidation and ion-exchange procedure by a zeolitic-imidazolate-framework-8 (ZIF-8)-templated method. Notably, the quantum size could be well controlled, and hence provide the ZnCdS QDs material with suitable band matching, strong electron coupling, uniform and abundant active sites, facilitated photoinduced charge kinetics, and shortened charge diffusion distances, which are vital merits for enhancing photocatalytic performance. The photocatalytic H2 production activity of these QDs can be optimized through adjusting the quantum sizes. Under the irradiation of visible-light and noble-metal cocatalyst-free, an optimal H2 production rate of 3.70 mmol h–1 g–1 could be afford without using noble metal cocatalysts, which is superior to those of bulk ZnCdS and most of the reported ZnCdS-based catalysts. The facile and efficient approach for ZnCdS QDs engineering could be extended to design other kinds of highly efficient metal-sulfide QDs in advanced applications.