Embedded Epitaxial Growth of RuO _x on Co ₃ O ₄ With Strong Interaction for Efficient and Robust Acidic Water Oxidation

ABSTRACT Constructing an intimate interface in supported catalysts for the acidic oxygen evolution reaction is an effective way to enhance the catalytic activity and durability. However, precisely regulating the supported interface still poses significant challenges. Herein, we propose a versatile two‐step drop‐casting approach to construct a RuO _x ‐Co ₃ O ₄ catalyst, in which RuO _x is embedded‐type supported on Co ₃ O ₄ oxides with an intimate dual‐oxide hetero‐interface to enhance the electronic interaction and construct robust Co‐O‐Ru motifs as electronic transfer channels. The timely replenishment of electrons on active Ru sites supplied by the Co ₃ O ₄ substrate prevents the formation of high‐valence Ru species and maintains the robust structural stability during the OER process. The embedded‐type structure strengthens the Co‐O‐Ru motifs and lowers the formation energy barrier of the ^* OOH intermediate. The embedment of RuO _x on Co ₃ O ₄ transfers the mechanism of coexisting adsorbate evolution mechanism (AEM) and lattice oxygen reaction (LOM) into the dominant AEM pathway. As a result, RuO _x ‐Co ₃ O ₄ exhibits an ultralow overpotential of 181 mV to achieve the current densities of 10 mA cm ⁻² , and operating durability for over 1000 h. This work proposes a versatile strategy for constructing intimate interfaces, which provides a perspective for the development of low‐noble‐metal mass‐loading supported catalysts in water electrolysis.