Ruthenium dioxide (RuO2) is a highly active catalyst for the oxygen evolution reaction (OER) in acidic proton exchange membrane (PEM) water electrolyzers, essential for sustainable green hydrogen production. However, its practical application is severely limited by corrosion under operating conditions, where surface Ru atoms dissolve to form soluble species such as RuO4, compromising long-term durability. This thesis employs density functional theory (DFT) combined with the computational hydrogen electrode (CHE) model to elucidate the atomistic mechanisms governing RuO2 surface corrosion and to establish rational design principles for enhancing stability through heteroatom doping with Ir, Ti, and W. The first study establishes the thermodynamic stability landscape of RuO2 surfaces against corrosion, comparing multiple facets and identifying the (110) surface as the most stable. Systematic investigation of dopant sublayers and quasi-random dopant distributions reveals that dopants favoring low oxidation states (Ir, Ti, Pt) enhance corrosion resistance, while those favoring high oxidation states (Ta, W, Re) destabilize the surface. Critically, dopant position, particularly at neighboring bridge sites or directly underneath the dissolving Ru atom, plays a decisive role in stability. A key methodological contribution is the establishment of the total Gibbs free energy of RuO4 formation (ΔGtot) as a reliable descriptor for corrosion resistance, validated by a strong correlation (R2 = 0.96) with ΔGmax, enabling efficient computational screening. The second study extends the analysis to a broader potential window (0–2.0SHE), revealing a potential-dependent switch in dissolution mechanisms. At high anodic potentials (above 1.21 VSHE), direct oxidative dissolution to RuO4 dominates. At lower potentials, proton-coupled pathways lead to formation of hydroxylated species (Ru(OH)4 and RuO2(OH)2). Two key surface intermediates (e and i) are identified as thermodynamic basins that persist during potential cycling, rationalizing experimentally observed transient dissolution during device shutdown and potential cycling. Electrochemical stability windows are computed for pure and doped RuO2(110) surfaces, demonstrating that Ir, Ti, and W dopants widen the stability window by shifting dissolution onset potentials. The third study addresses the critical question of whether stability enhancements compromise catalytic activity. Free-energy analysis identifies *OOH formation at coordinatively unsaturated Ru sites as the rate-determining step across all configurations. Bader charge and crystal orbital Hamilton population (COHP) analyses reveal that bridge-site dopants modulate Obr basicity and M–Obr covalency, while cus-site dopants redistribute electron density within the Ru–O framework. Remarkably, Ti at bridge sites simultaneously increases intrinsic OER activity by ~200% while raising ΔGmax for corrosion by ~0.9 eV, corresponding to orders-of-magnitude reduction in corrosion rate. Ir at cus sites also improves activity with significant stabilization, while W provides only modest benefits. These findings demonstrate that the conventional activity–stability trade-off can be broken through rational, site-specific dopant placement. Together, these three studies provide a comprehensive mechanistic framework for understanding RuO2 corrosion under realistic operating conditions and establish design principles for optimizing both activity and stability. The key insight is that dopant identity alone is insufficient, precise control of dopant placement at cus versus bridge sites is essential for achieving optimal performance. This work provides a structural blueprint for the development of durable, high performance RuO2-based OER catalysts for acidic water electrolysis.
Badr Saleh Badr Mohamed Elkamash (Thu,) studied this question.