Generating clean drinking water is an emerging global challenge, especially in remote locations, areas encountering natural disasters, or where environmental pollution is unchecked. Water purification strategies must often address the removal or mitigation of many types of contaminants, including salts, organic pollutants, and pathogens. One avenue to sanitize water harnesses the chloride content of seawater or brackish water to electrochemically generate hypochlorite species that provide disinfecting function. A major challenge to this approach is that the thermodynamic potential to oxidize chloride to molecular chlorine (1.36 V vs SHE) is higher than water oxidation (1.23 V vs SHE). Thus, electrocatalysts should be chosen based on their ability to kinetically favor chloride oxidation. Ruthenia-based electrodes show promise in such regard, but conventionally in the form of microns-thick coatings that do not efficiently utilize this precious-metal oxide. As an alternative, we vapor-deposit RuO₂ onto the surface of acid-etched titanium mesh, resulting in RuO₂ coatings that are < 10 nm thick. Preliminary results reveal that these RuO₂/Ti electrodes are effective at preferentially oxidizing chlorine over water, even at such ultralow mass loadings of RuO₂. We investigate the impact of deposition parameters and post-deposition thermal treatment on the electrocatalytic activity, selectivity, and stability of RuO₂/Ti electrodes and compare their performance to state-of-the-art electrocatalysts for hypochlorite generation. The efficacy of these RuO₂/Ti electrodes is further demonstrated in test cells where electrogenerated hypochlorite species are used to kill E. coli.
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Meghanne Tighe

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