Catalytically Active Cr2O3-Decorated Spinel MnCo2O4 Nanobelt for Bifunctional Electrocatalytic Water Splitting Reaction

Abstract

Electrocatalytic water splitting using nonprecious metal-based catalysts is significantly important for clean energy production and storage sectors. The existence of Mn and Co metals in the spinel MnCo2O4 structure may influence the electrocatalytic performance synergistically

hence, incorporating it with additional active species can further enhance the catalytic activity. Here, Cr2O3 nanoparticles are used to decorate the surface of a MnCo2O4 nanobelt, in which Cr2O3 acts as an active site for the electrocatalytic reactions. The Cr2O3 nanoparticles can be strategically distributed on the surface of the MnCo2O4 nanobelt, developing a highly efficient catalyst system. The Cr2O3-decorated MnCo2O4 electrocatalyst requires low overpotentials of 213 and 144 mV to achieve 10 mA cm–2 for OER and HER, respectively, facilitating faster electron transfer kinetics, and its enhanced performance may be attributed to two reasons. First, the Cr2O3 nanoparticles increase the surface area of the catalyst, providing more active sites, which leads to improved electrocatalytic efficiency and enhanced kinetics. Second, introducing Cr2O3 alters the electronic structure and surface properties of MnCo2O4, resulting in modified reaction pathways and reduced energy barriers for water-splitting reactions, which are confirmed by theoretical calculations. Furthermore, the Cr2O3-decorated MnCo2O4 nanobelt exhibits good stability and durability, making it suitable for long-term water-splitting applications. The turnover frequency (TOF) of Cr2O3/MnCo2O4 was calculated to be 5.79 × 10–2 s–1. The synergistic combination of MnCo2O4 and Cr2O3 results in a bifunctional catalyst that can efficiently facilitate oxygen and hydrogen evolution reactions, making it a promising candidate for overall water splitting. © 2026 American Chemical Society