Molybdenum disulfide quantum dots decorated bismuth sulfide as a superior noble-metal-free photocatalyst for hydrogen evolution through harnessing a broad solar spectrum

Molybdenum disulfide quantum dots (MoS₂QDs) decorated bismuth sulfide (Bi₂S₃) photocatalyst was synthesized. Photoluminescence characterization showed that the as-developed MoS₂QDs possessed intriguing up-conversion and down-conversion properties, indicating their capability to harness energy from the light spectrum ranging from ultraviolet (UV) to near-infrared (NIR). In this study, the highest hydrogen yield of 17.7 mmol/g.h was achieved by 0.14MoS₂QD/Bi₂S₃, which was almost 4.5 folds higher than that of undoped Bi₂S₃ under stimulated solar light irradiation. Furthermore, examination of the 0.14MoS₂QD/Bi₂S₃ photocatalysts under NIR irradiation showed a significant photocurrent response and an accumulative H₂ yield of 53.6 μmol/g after 6 h reaction. This is a major breakthrough as most photocatalysts can only be activated under UV and/or visible light irradiation. This work provides new insights into the design of MoS₂QD/Bi₂S₃ for harnessing energy from a broad solar spectrum to photocatalytically split water to produce hydrogen.