CNT-modified CeO₂-ZnO Nanohybrid for superior photocatalytic and electrocatalytic activity

Photocatalysis and electrochemical analysis play a significant role in addressing energy and environmental challenges. In this study, we investigate the photocatalytic degradation of Rhodamine B (RhB) dye and the electrocatalytic properties of CeO₂, CeO₂-ZnO (binary) and CeO₂-ZnO-CNT ternary nanocomposites. While the synthesis and basic characterization of CeO₂ and CeO₂-ZnO (binary) have already been reported in earlier studies, the ternary composite was synthesized via a simple chemical route and characterized in detail using X-ray diffraction (XRD), Raman spectroscopy, UV–Vis spectroscopy, Transmission Electron Microscopy (TEM) and Energy-Dispersive Spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) studies were performed to determine the surface elemental composition and explain the oxidation states of the constituent elements. Photocatalytic performance was evaluated for all three composites under sunlight and UV light, with the ternary nanocomposite exhibiting the highest degradation efficiency (∼95 %) under UV light for RhB dye. Scavenger studies using triethanolamine (TEA), isopropanol (IPA), and benzoquinone (BQ) were carried out to determine the key reactive species involved in the photocatalytic process. The electrochemical properties of all three samples-CeO₂, CeO₂-ZnO and CeO₂-ZnO-CNT were examined for the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) in 1 M KOH electrolyte. The ternary composite exhibited significant electrocatalytic activity with onset potentials of 0.06 V for HER and 1.61 V for OER demonstrating its potential for renewable energy conversion. The combined photocatalytic and electrochemical analysis highlights the versatility of these nanocomposites, making them promising candidates for energy and environmental applications.