ZnO/RuO2 nanostructured composites with enhanced bifunctional photo-electro catalytic activity toward water splitting

Abstract

The demand for affordable and accessible catalysts to replace the expensive and scarce resourced platinum group metals (PGMs) has become increasingly vital. Since they combine different properties such as electrochemical activities, chemical and photochemical stability, non-toxicity, etc. ZnO-based materials have been examined for potential applications in electronics, optoelectronics, sensing in environmental applications as well as catalysis. This study focused on cost reduction of PGM materials by introducing RuO2 as a substitute for Ru and decreasing the amount of RuO2 through the incorporation of abundant and versatile ZnO. A composite of ZnO/RuO2 in a 10:1 molar ratio was synthesized using a microwave processing of a prepcipitate. To enhance its catalytic properties, the composite was subsequently annealed at 300 and 600 C. The physicochemical characteristics of the ZnO/RuO2 composites were analyzed using X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Furthermore, the electrochemical activity of the samples was assessed through linear sweep voltammetry in both acidic (0.1 M H2SO4) and alkaline (0.1 M NaOH) electrolytes. Remarkably, the ZnO/RuO2 composites exhibited excellent bifunctional catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both types of electrolytes.