Interfacial Water‐Networks Regulate the Anodic Stability of Carbon Electrodes

Carbon-based materials are widely used in modern electrochemical technologies, yet their susceptibility to oxidation at positive electrode potentials poses a durability challenge. While this degradation has commonly been addressed through modification of the carbon material itself, the interfacial chemistry that activates carbon oxidation remains poorly understood. Here, we show that the hydrogen-bonding (HB) network of interfacial water strongly influences anodic carbon stability. Operando differential electrochemical mass spectrometry combined with in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy reveals that corrosion accelerates as the interfacial HB network becomes increasingly disrupted, implicating weakly H-bonded water as a reactive water population associated with carbon oxidation. Guided by this mechanistic insight, we modulate the local water structure using ionomer-defined interfaces. In a case study of chlorine evolution on a carbon-supported single-atom Pt catalyst, Sustainion-defined interfaces preserve a more ordered interfacial water-network and suppress carbon corrosion relative to Nafion-defined interfaces, whereas the latter promote surface charging favorable for chlorine evolution kinetics. By combining these functions in a mixed-ionomer layer, water-network-guided stabilization is implemented under anodic electrocatalytic operation with suppressed carbon corrosion. This work highlights interfacial water-network modulation as a promising design principle for extending the anodic stability of carbon-based electrodes.