CdS Nanospheres Decorated with NiS Quantum Dots as Nobel-Metal-Free Photocatalysts for Efficient Hydrogen Evolution

Noble-metal-free photocatalysts have attracted tremendous interest in recent years. Among them, cadmium sulfide (CdS) has been considered as one of the most important photocatalysts with potential applications in hydrogen evolution. However, its efficiency is relatively low due to the fast recombination of photogenerated charge carriers. In this work, defective CdS nanospheres were designed. NiS quantum dots were introduced to facilitate the efficient separation of photogenerated electrons and holes. Without noble metals, the hydrogen production of CdS nanospheres with NiS quantum dots is similar to 24 times higher than that of pure CdS nanospheres, demonstrating the key role of NiS quantum dots for highly efficient separation of the photogenerated carriers. Meanwhile, the designed photocatalysts have good stability. They can maintain similar to 90% of photocatalytic activity during stability measurements. A potential photocatalytic mechanism was proposed.