Enhanced visible-light-driven photocatalytic hydrogen generation using NiCo2S4/CdS nanocomposites.

• NiCo 2 S 4 /CdS showed excellent HER with lactic acid under visible light irradiation. • Ultrafast dynamics studies showed that NiCo 2 S 4 /CdS had more efficient charge separation. • The mechanism enhanced performance of the NiCo 2 S 4 /CdS nanocomposites were revealed. One-dimensional NiCo 2 S 4 /CdS nanocomposites are constructed using a two-step hydrothermal method and used for photocatalytic hydrogen generation with visible light. The nanocomposites are characterized using a combination of techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), positron annihilation lifetime measurement, spectroscopy techniques, and femtosecond transient absorption (TA) spectroscopy. In comparison to bare CdS NWs, the NiCo 2 S 4 /CdS nanocomposites exhibit enhanced visible light hydrogen production, with an optimal rate reaching 20.0 mmol·h−1·g−1. The experimental results, in conjunction with theoretical electronic structure calculations, reveal that the enhanced hydrogen evolution reaction activities can be attributed to the formation of Schottky junction between NiCo 2 S 4 NPs and CdS NWs that facilitates photogenerated electron transfer from CdS to NiCo 2 S 4. Meanwhile, the NiCo 2 S 4 , as a metallic cocatalyst, increases the electron density and active sites desired for H 2 evolution. [ABSTRACT FROM AUTHOR]