Carbon is an indispensable material in the electrochemical field, primarily due to its exceptional electrical conductivity and its role in the cost-effective development of sustainable energy systems. However, the performance of these systems is frequently impaired by carbon corrosion, which can result in the collapse of catalytic networks and disruption of electrical contacts in devices. Despite numerous studies reporting on the degradation phenomena induced by carbon corrosion, the underlying reaction mechanisms remain largely uncertain. Here, we elucidate that carbon corrosion is initiated by a covalent addition reaction that chemically breaks the sp² carbon network prior to the electrochemical oxidation steps. Specifically, online differential electrochemical mass spectrometry (DEMS) and post-mortem X-ray photoelectron spectroscopy (XPS) reveal that carbon corrosion reaction has a pseudo-zeroth and first-order reaction kinetics concerning proton concentration and oxygen coverage on the carbon surface, respectively. Our proposed mechanism was evidenced by the decreased corrosion rate in the presence of the carbocation scavenger, methanol, and by the evolution of the C¹⁸O¹⁶O product during the corrosion, pretreated in acid solution prepared with the ¹⁸O-isotope of water. This finding successfully explains previous empirical observations, including pH-dependent and site-specific (defect, edge, etc.) characteristics of carbon corrosion. The research provides valuable insights for refining strategies to prevent degradation induced by carbon corrosion and to effectively manage the performance of electrical devices.

Carbon is an indispensable material in the electrochemical field, primarily due to its exceptional electrical conductivity and its role in the cost-effective development of sustainable energy systems. However, the performance of these systems is frequently impaired by carbon corrosion, which can result in the collapse of catalytic networks and disruption of electrical contacts in devices. Despite numerous studies reporting on the degradation phenomena induced by carbon corrosion, the underlying reaction mechanisms remain largely uncertain. Here, we elucidate that carbon corrosion is initiated by a covalent addition reaction that chemically breaks the sp² carbon network prior to the electrochemical oxidation steps. Specifically, online differential electrochemical mass spectrometry (DEMS) and post-mortem X-ray photoelectron spectroscopy (XPS) reveal that carbon corrosion reaction has a pseudo-zeroth and first-order reaction kinetics concerning proton concentration and oxygen coverage on the carbon surface, respectively. Our proposed mechanism was evidenced by the decreased corrosion rate in the presence of the carbocation scavenger, methanol, and by the evolution of the C¹⁸O¹⁶O product during the corrosion, pretreated in acid solution prepared with the ¹⁸O-isotope of water. This finding successfully explains previous empirical observations, including pH-dependent and site-specific (defect, edge, etc.) characteristics of carbon corrosion. The research provides valuable insights for refining strategies to prevent degradation induced by carbon corrosion and to effectively manage the performance of electrical devices.