Fabrication of Cd0·5Zn0·5S nanoparticles decorated TiO2 nanotube arrays electrode and its enhanced photoelectrocatalytic performance

Cd0·5Zn0·5S nanoparticles modified TiO2 nanotube arrays composite electrodes (Cd0·5Zn0·5S/TiO2 NTAs) were successfully synthesized by the combination of electrochemical oxidation and hydrothermal process under various thiourea concentrations. The as-prepared electrodes were systematically characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance absorption spectra techniques. The influence of thiourea concentrations on the morphology structure, photoelectrochemical properties, and hydrogen production of Cd0·5Zn0·5S/TiO2 NTAs electrodes was systematically investigated. The Cd0·5Zn0·5S/TiO2 NTAs electrode fabricated at 8 mM thiourea concentration exhibits the highest hydrogen production rate of 523.1 μmol/(h∙cm2) and the maximum photocurrent density of 26.73 mA/cm2 under visible light illumination. The corresponding apparent quantum efficiency (QE) and visible-photoconversion efficiency are 55.2% and 11.97%, respectively. Electrochemical impedance spectroscopy (EIS) analysis of Cd0·5Zn0·5S/TiO2 NTAs electrode further demonstrates the enhanced photoelectrochemical performance, which can be attributed to the favorable microstructure and enhanced charge transfer.