Facile synthesis of a novel full-spectrum-responsive Co2.67S4 nanoparticles for UV-, vis- and NIR-driven photocatalysis

Sparked by growing pollution issues, research aiming at a better harvesting of solar energy in photocatalysts for environmental remediation has been thriving. In this study, a novel mixed valence state of Co2.67S4 nanoparticles with full-spectrum-responsive photocatalytic activity had been fabricated via a facile solvothermal route. The as-synthesized samples were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis-NIR diffuse reflection spectroscopy (UV–vis-NIR DRS). The photocatalytic performance of as-obtained samples had been investigated by the degradation of methylene blue (MB) in aqueous solution. The Co2.67S4 nanoparticles with the particle size of 5–20 nm could degrade MB with the efficiency of 64%, 84% and 68% under the UV light, visible light and near-infrared light exposure, respectively. Furthermore, a possible photocatalytic mechanism toward the near-infrared region had been proposed to be that the Co2+/Co3+ redox couple played vital parts in the photocatalytic activity of Co2.67S4. This study provides a novel full solar spectrum-responsive photocatalyst for solar-light utility and environmental remediation.