Enhanced photocatalytic activity of Zn-doped dendritic-like CdS structures synthesized by hydrothermal synthesis

• Low Zn2+ doping concentration can keep the dendritic-like structures of CdS.
• Doping Zn2+ can improve the absorbing capability of dendritic-like CdS for the visible light.
• The content of Zn2+ affects the band gap of Zn-doped CdS structures.
• Doping Zn2+ is conducive to improve the photocatalytic efficiency to methylene blue.
• Photocatalytic mechanism of Zn:CdS to methylene blue is reasonable, clear and concise.

In this work, a series of Zn-doped dendritic-like CdS structures have been synthesized by a simple hydrothermal method. The as-prepared samples have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), ultraviolet-visible (UV–vis) and room temperature photoluminescence (PL). Their photocatalytic activities have been evaluated by the photocatalytic degradation of methylene blue (MB) under simulated visible-light irradiation. XRD results indicate that the phase of Zn:CdS was hexagonal phase. XRD and EDS results indicate that Zn2+ was successfully introduced into CdS. FESEM results indicate that low Zn2+ doping concentration can keep the dendritic-like CdS structures, but the morphologies of Zn:CdS are flower-like structures at high Zn2+ doping concentration. UV–vis results indicate that doping Zn2+ can be used to improve the absorbing capability of dendritic-like CdS for visible light, and the content of Zn2+ affects the band gap. PL results indicate that doping Zn2+ can be used to improve the luminescence property of dendritic-like CdS. Photocatalytic results indicate that doping Zn2+ is conducive to improve the photocatalytic efficiency of dendritic-like CdS to MB, and the highest degradation rate is 92.8%. And the photocatalytic mechanism of Zn-doped dendritic-like CdS to MB is also described.