Asymmetric Ru–O–Co sites coupled adsorbate evolution and oxide pathway mechanisms for enhanced acidic water oxidation

While RuO 2 is a benchmark catalyst for acid oxygen evolution reaction (OER), its performance is constrained by the adsorbate evolution mechanism (AEM). Coupling AEM with the more efficient oxide pathway mechanism (OPM) could address this constraint, but the large Ru–Ru interatomic distance in RuO 2 (>3.1 Å) inherently suppresses OPM activation. Experiments and theory confirm that non-interface Ru–O–Ru and Co–O–Co sites with large interatomic distances favor the AEM by stabilizing the key *OOH intermediate, while the short asymmetric interfacial Ru–O–Co bridges (<2.4 Å) promote direct *O–*O coupling, thereby selectively triggering OPM and enabling a synergistic dual-pathway OER. This interfacial engineering also enhances the antioxidant capacity of Ru and accelerates reaction kinetics. As expected, the inter-RuO 2 /Co 3 O 4 demonstrates exceptional activity and stability, achieving overpotentials of only 196 mV and 370 mV at 10 and 500 mA cm −2 , respectively, and operating steadily for over 100 h at 500 mA cm −2 , far surpassing commercial RuO 2 . This work provides a general strategy for activating complementary reaction pathways by selectively triggering the OPM via short-range asymmetric Ru–O–Co sites.