Three-step fabrication of TiO2CdS spheres on SiO2 supports for enhanced hydrogen evolution performance

Abstract

Development of novel, low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER) is crucial for sustainable energy applications. In this study, a SiO₂-supported TiO₂CdS spherical composite is presented as a highly effective catalyst for enhanced hydrogen evolution performance. This composite material was synthesized through a three-step process of materials engineering. XRD analysis revealed reduced SiO₂ peak intensity (25°) while UV–vis data indicate a narrowed bandgap (from 2.63 eV to 2.11 eV) with CdS incorporation, confirming surface modification and visible-light responsiveness. FTIR identified Ti–O–Cd interactions and O–H bending vibrations, while TEM imaging demonstrated uniform SiO₂ spheres (200–250 nm) with dense CdS coverage, corroborating successful hierarchical integration. Finally, electrochemical measurements were performed to evaluate the material's electrocatalytic HER performance. The overpotential exhibited a notable decrease from 793 mV to 264 mV at a current density of 10 mA/cm², demonstrating the improved electrocatalytic efficiency as CdS concentration increased. Furthermore, Tafel slope analysis revealed enhanced hydrogen evolution kinetics, with the slope reducing from 189 to 127 mV/dec as CdS content increased. Electrochemical impedance spectroscopy (EIS) results revealed semicircular Nyquist plots for all samples, with the highest CdS-containing sample showing a smaller semicircle, indicating a substantial reduction in charge transfer resistance.