Zn-Doped Ca Germanate Nanowires and Their Photocatalytic Activity for the Degradation of Methylene Blue

Zn-doped Ca germanate nanowires have been prepared by the hydrothermal method from 180 °C for 24 h. X-ray diffraction (XRD) shows that the Zn-doped Ca germanate nanowires with the rhombohedral Ca₃GeO₅ and rhombohedral ZnGeO₃ phases have been obtained. Scanning electron microscopy (SEM) shows that the Zn-doped Ca germanate nanowires have the average diameter and length of 50–200 nm and several dozens of micrometers, respectively. Zn-doping causes the red shift of the band gap of the Ca germanate nanowires based on the UV-vis diffuse reflectance spectroscopy measurements. The photocatalytic activity of the Zn-doped Ca germanate nanowires for the degradation of methylene blue (MB) solution under UV light irradiation depends on the Zn-doping mass percentage. The photocatalytic activity is best enhanced in the Zn-doped Ca germanate nanowires with the Zn-doping mass percentage of 10%.