Facet-engineered ruthenium oxide on titanium oxide oxygen evolution electrocatalysts for proton-exchange membrane water electrolysis

Ruthenium oxide-based catalysts exhibit an active oxygen evolution reaction (OER) in acidic media but suffer from low stability, limiting their practical application in proton-exchange membrane water electrolyzers (PEMWEs). Herein, we present an effective acidic OER catalyst comprising RuO2 nanolayers on an isostructural rutile TiO2 support (NL-RuO2-250) that maximizes exposure to specific crystal orientations. RuO2 morphology and growth mechanism on the TiO2 surface were affected by the interfacial charge states during hydrothermal process, with the crystal structure similarity between the RuO2 catalyst and TiO2 support advantageous for maximizing compatibility at the interface. Density functional theory combined with experimental analyses revealed that NL-RuO2-250 is an optimized form for improving OER performance. As-prepared NL-RuO2-250 required a low overpotential (230 mV at 10 mA cm−2) and a PEMWE single cell assembled with NL-RuO2-250 exhibited an insignificant voltage drop for 24 h under 0.2 A cm−2, demonstrating a practical design strategy for acidic OER catalysts. © 2024 Elsevier B.V.