Synthesis of ruthenium oxide nanosheets with fourth-period elements for alkaline oxygen evolution reaction.

A comprehensive series of Ru-based bimetallic oxide nanosheets with fourth-period elements (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, and Ga) was synthesized via a unified puffing-template combustion method and systematically evaluated for the alkaline oxygen evolution reaction (OER). As revealed by X-ray diffraction, among the examined metals, Cr and Ga exclusively induced chemically selective solid-solution formation within the rutile RuO2 lattice, a structural prerequisite for modulating the electronic structure of the active Ru sites and enhancing the OER activity. The OER activity of the optimal compositions Ru0.38Ga0.62Ox and Ru0.71Cr0.29Ox surpassed that of pristine RuOx. However, a 50 h chronopotentiometric study revealed a decisive shift in the activity-stability relationship, with Ru0.71Cr0.29Ox maintaining a nearly constant operating potential, whereas Ru0.38Ga0.62Ox rapidly deactivated due to Ga3+ leaching. X-ray photoelectron spectroscopy and electron microscopy confirmed that Cr3+ acts as a valence-pinning agent, suppressing Ru oxidation, thereby reducing the density of oxygen vacancies and number of stable covalent Ru-O bonds. The results demonstrate that Ru0.72Cr0.29Ox is a promising and durable anode for the alkaline OER and highlight the importance of durability testing in concurrence with overpotential benchmarking.