Enhanced photocatalytic hydrogen evolution from band-gap tunable Ag2S:X (X = Ni, Co, Zn, Mn) nanocrystals: Effect of transition metal ions

In the present work, Ni, Co, Zn and Mn doped Ag2S nanocrystal catalysts were prepared via the hot-injection technique which is one of the top-down approach. The nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), diffuse reflectance spectroscopy (DRS), UV - vis spectroscopy (UV) and cyclic voltammetry (CV) to illuminate the crystal properties and the photocatalytic mechanism. The presence of doping each of the transition metals on Ag2S nanocrystals were tested for their performance in the photocatalytic hydrogen evolution from water containing TEOA and EY as a hole scavenger and photoabsorber, respectively. The results demonstrated that Ni, Co, Zn and Mn doped Ag2S nanocrystals were showed higher photocatalytic activity as compared with the Ag2S under visible light irradiation source. In addition, transition metal consisting Ag2S catalysts, which in view of the limited literatures, provides new insights for expanding the application of chalcogenide catalysts.