Quantum Size Effect of Cadmium-Doped Titanium Dioxide Photocatalysts Towards Methylene Blue Degradation and Electrooxidation

Abstract

At present, titanium dioxide supported cadmium catalysts were prepared at 0.5-5% cadmium loading by impregnation method. 0.5% Cd/TiO2 catalyst was characterized with scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Characterization results revealed that by cadmium doping to titanium dioxide, surface electronic properties and crystal structure of Cd/TiO2 catalysts changed as obtained from SEM-EDX, XRD, and XPS. Following this, methylene blue degradation and electrochemical oxidation measurements were examined under UV light. Electrooxidation measurements were investigated to determine the methylene blue electrooxidation activities of titanium dioxide supported cadmium catalysts prepared at 0.5-5% cadmium loading with the cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in 1 M KOH + 0.1875 M Methylene blue solution at 100 mV s(-1) in the dark and under UV light. Methylene blue oxidation measurements revealed that 0.5% Cd/TiO2 had the highest catalytic activity and stability in the dark and under UV illumination. 0.5% Cd/TiO2 electrode exhibited enhanced electrocatalytic activity under UV illumination. Photocatalytic methylene blue oxidation enhanced for 0.5% Cd/TiO2 by altering the surface electronic structure and crystal properties of titanium dioxide, assigned to structure sensitivity. As a result, this electrode production method is promising for the photocatalytic water remediation.