Atomic Ru‐Mediated Spontaneous Heterointerface Phase Transition Enables Ampere‐Level Catalytic Performance in Paired Electrolysis

Abstract Phase transition regulation is a promising strategy to optimize the catalytic properties of catalysts, playing a crucial role in enhancing electrocatalytic efficiency. However, the intrinsic relationship between atomic‐scale interface phase transitions and catalytic performance remains unclear. Herein, we report a heteroatomic interfacial phase transition of Co 3 S 4 /Co heterostructured nanosheets to Co 9 S 8 /Co by anchoring single‐atom Ru under thermal treatment (Ru SA –Co 9 S 8 /Co–T), resulting in ampere‐level catalytic performance for the sustained paired electrosynthesis. Theoretical calculations and in situ spectroscopy confirm the spontaneous transition to a more stable structure triggered by atomic Ru, which synergistically optimizes the formation kinetics of key intermediates and reduces the energy barrier of the rate‐determining steps on Ru SA ‐Co 9 S 8 /Co–T. Impressively, this catalyst can be directly applied in membrane electrode assembly electrolyzers for nitrite‐glycerol co‐electrolysis. Within a wide potential window of 1.2–2.0 V, the average Faradaic efficiencies of NH 3 and formate exceed 90%, with the highest yields reaching 95.83 mg h −1 cm −2 and 567.38 mg h −1 cm −2 at 2.0 V, respectively, alongside stable operation for 100 h at an industrial current density of 500 mA cm −2 . Our work provides new insights into the development of high‐performance catalysts.