Keeping water molecules connected reduces carbon electrode corrosion

Carbon electrodes are widely used in technologies like fuel cells and water electrolyzers, but they corrode over time under strongly oxidizing conditions. Researchers at the University of Osaka discovered that water molecules directly adjacent to the electrode play a crucial role in this degradation process. By monitoring carbon corrosion and the interfacial water network during operation, they found that as the network connecting nearby water molecules became more disrupted, corrosion accelerated.

Weakly connected water appeared to be more involved in the oxidation of carbon to carbon dioxide. To address this issue, the team experimented with reorganizing the water environment around the electrode using ion-conducting polymers called ionomers. They found that Sustainion, a new type of ionomer, created a more strongly connected water network compared to the commonly used Nafion and reduced carbon corrosion by approximately 51%.

In a chlorine-producing system, combining Sustainion with Nafion retained high initial catalytic activity, with only a 19% performance loss after 500 cycles. The researchers conclude that designing the environment surrounding an electrode, in addition to the electrode material itself, could significantly improve its durability. This finding highlights control of interfacial water as a promising design principle for carbon electrodes, potentially leading to longer-lasting electrochemical technologies including green hydrogen production, chlorine manufacturing, and fuel cells.