Advances in RuO₂-based heterostructures as high-performance electrocatalysts toward electrochemical water splitting

The global pursuit of carbon neutrality has deepened people's understanding of green hydrogen, thereby accelerating the growing demand for this clean energy carrier. Among the existing production strategies, water electrolysis remains the only commercially viable way to produce zero-carbon-emission green hydrogen. Ru-based materials, especially ruthenium oxide (RuO₂), exhibit great potential in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of water electrolysis due to their high intrinsic activity and comparative cost advantages. However, RuO₂ is prone to oxidative dissolution during water electrolysis, leading to structural instability and activity decay. This stability issue has become a key bottleneck restricting its practical application. Constructing heterojunction catalysts provides a feasible path to surpass the performance limitations of single-component materials. By forming interfacial coupling between RuO₂ and functional materials, including metals, metal oxides, and nonmetallic compounds, the adsorption energy of reaction intermediates is optimized, thereby enhancing catalytic activity while inhibiting the dissolution of active components and improving structural stability. This review provides a systematic overview of recent advances in RuO₂-based heterojunction electrocatalysts for water electrolysis across both acidic and alkaline environments. This review specifically elucidates the design and synthesis strategies and discusses the related mechanisms for performance improvement. Furthermore, this review analyzes the remaining challenges in the synergistic tuning of the activity and stability of RuO₂-based heterojunction catalysts and outlines prospective research directions to address these gaps.