Can dopants defend? Unraveling RuO2 corrosion and reinforcement strategies for enhanced stability

Abstract

To advance sustainable green hydrogen production through water electrolysis, where ruthenium dioxide (RuO₂) is a promising catalyst for the oxygen evolution reaction (OER), we investigate the stability of RuO₂, focusing on corrosion resistance – a key challenge limiting its practical application. Using density functional theory (DFT), we analyze the thermodynamic stability and reaction pathways across various RuO₂ surface orientations, with a primary focus on the (110) surface. Specifically, we assess the impact of doping with Ta, W, Re, Ir, Ti, and Pt on the thermodynamic stability of the RuO₂(110) surface against dissolution of Ru surface atoms in the form of RuO₄. Our findings reveal that dopants Ir, Ti, and Pt in low oxidation states significantly enhance the resistance of the RuO₂(110) surface against corrosion, while Ta, W, and Re in high oxidation states destabilize the surface, promoting degradation. We also identify specific dopant sites, such as those next to or directly underneath the dissolving Ru atom, that contribute significantly to surface stability, providing a roadmap for optimizing RuO₂ catalysts. Additionally, we extend the investigation to reaction pathways towards the dissolution of the Ru atom by incorporating the effects of dopants, revealing that dopants not only alter the thermodynamic stability but also the reaction mechanism due to their different termination preferences. We establish a strong linear correlation between the Gibbs free energy of RuO₄ formation (ΔG_tot) and the free energy of the highest intermediate (ΔG_max), proposing ΔG_tot as a reliable descriptor for predicting the thermodynamic stability of doped RuO₂ surfaces against Ru dissolution. This allows for efficient computational screening of surface modifications, including dopant selection and surface orientation tuning, without requiring detailed knowledge of the entire stepwise mechanism toward the formation and removal of RuO₄. This insight enables efficient computational screening of dopants and surface modifications, providing a framework for optimizing RuO₂ catalysts to improve durability in electrochemical applications.