Localized NiS2 Quantum Dots on g-C3N4 Nanosheets for Efficient Photocatalytic Hydrogen Production from Water

Developing high-efficiency yet low-cost photocatalyst for solar hydrogen production by avoiding the use of noble metals has received adequate interest but remains a great challenge to date. This work reports a seed-mediated hydrothermal approach for the synthesis of NiS2 quantum dots (QDs) anchored two-dimensional graphitic carbon nitride (g-C3N4) nanosheets. This hybrid shows superior performance toward photocatalytic H-2 evolution from water. The highest H-2 evolution rate reaches 4.841 mu molh(-1), with an apparent quantum efficiency of 2% at 425nm, which is even much higher than that of Pt-modified g-C3N4 photocatalyst (2.865 mu molh(-1)). Moreover, the composite presents good stability without notable activity decay after several cycled tests. It is found that NiS2 QDs are essential for this improvement. These small nanoclusters not only benefit rapid and vectorial diffusion of photogenerated electrons from g-C3N4 to NiS2, but also promote H-2 evolution by decreasing the thermodynamic overpotential for proton reduction. This work thus marks an important step toward designing good-performance and low-cost photocatalytic materials for solar H-2 conversion.