Tailoring the ZnO/RuO2 ratio in composite electrocatalysts for efficient HER and OER

Abstract

The increasing demand for efficient catalysts has raised concerns about the limited availability and high cost of platinum group metal (PGM) catalysts. Ruthenium dioxide (RuO2) has shown remarkable catalytic activity; however, its extensive use is hindered by its high cost. To tackle this challenge, we investigated the utilization of zinc oxide (ZnO) as a promising alternative to reduce reliance on expensive RuO2 catalysts while maintaining catalytic performance by synthesizing ZnO/RuO2 composites in various mass ratios (1:1, 2:1, 10:1) through microwave processing of a precipitate, followed by calcination at temperatures of 300 and 600 °C. The crystallinity and phase purity of the particles were analyzed using Xray powder diffraction (XRD) and Raman spectroscopy. Surface chemistry was examined by Fourier-transform infrared (FTIR) spectroscopy. Field emission scanning electron microscopy was employed to investigate the morphology and particle size. Photoluminescence and UVVis diffuse reflectance spectroscopy were utilized for analyzing the optical properties. The electrocatalytic activity of the materials were evaluated via linear sweep voltammetry in both acidic (0.1 M H2SO4) and alkaline (0.1 M NaOH) electrolytes. The ZnO/RuO2 composites exhibited outstanding catalytic performance for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in both types of electrolytes.