Interface engineering of RuO2/Ru–Co3O4 heterostructures for high-efficiency oxygen evolution in acid

Abstract

Proton exchange membrane water electrolysis (PEMWE) powered by renewable electricity is a promising technology for green hydrogen production. Ru-based catalysts are a cost-effective alternative to Ir-based counterparts for the oxygen evolution reaction (OER), yet achieving balanced activity and stability remains challenging. In this study, we optimize the performance of RuO₂ by constructing RuO₂/Ru–Co₃O₄ heterogeneous interfaces. Our results indicate that RuO₂/Ru–Co₃O₄ catalyst pyrolyzed at lower temperatures exhibits uniformly small particle sizes with abundant heterointerfaces and strong interfacial electronic interactions. Elevated pyrolysis temperatures enlarge catalyst particle sizes, simultaneously decreasing heterointerfaces and weakening the interfacial interactions. In rotating disk electrode experiments, the mass activity of the RuO₂/Ru–Co₃O₄ catalysts is significantly improved compared to the commercial RuO₂. This improvement is attributed to the heterogeneous interfaces, which offer greater utilization of active sites and enhanced charge transfer capabilities. Furthermore, the mass activity of the RuO₂/Ru–Co₃O₄ catalysts decreases with increasing pyrolysis temperatures due to the reduction in heterogeneous interfaces. Additionally, the stability of the RuO₂/Ru–Co₃O₄ catalysts is notably superior to that of commercial RuO₂, owing to the interfacial electronic interactions. However, this stability is negatively impacted by higher pyrolysis temperatures as the interfacial electronic interactions weaken. In preliminary membrane electrode assembly tests, the RuO₂/Ru–Co₃O₄ catalyst with low Ru loading shows higher activity than commercial RuO₂. Further triple-phase boundary optimization of the catalyst layer is needed. These findings contribute to advanced RuO₂-based catalyst design for PEMWE.