Electrosynthesis of chlorine from seawater-like solution through single-atom catalysts.

The chlor-alkali process plays an essential and irreplaceable role in the modern chemical industry due to the wide-ranging applications of chlorine gas. However, the large overpotential and low selectivity of current chlorine evolution reaction (CER) electrocatalysts result in significant energy consumption during chlorine production. Herein, we report a highly active oxygen-coordinated ruthenium single-atom catalyst for the electrosynthesis of chlorine in seawater-like solutions. As a result, the as-prepared single-atom catalyst with Ru-O moiety (Ru-O SAM) exhibits an overpotential of only ~30 mV to achieve a current density of 10 mA cm in an acidic medium (pH = 1) containing 1 M NaCl. Impressively, the flow cell equipped with Ru-O SAM electrode displays excellent stability and Cl selectivity over 1000 h continuous electrocatalysis at a high current density of 1000 mA cm. Operando characterizations and computational analysis reveal that compared with the benchmark RuO electrode, chloride ions preferentially adsorb directly onto the surface of Ru atoms on Ru-O SAM, thereby leading to a reduction in Gibbs free-energy barrier and an improvement in Cl selectivity during CER. This finding not only offers fundamental insights into the mechanisms of electrocatalysis but also provides a promising avenue for the electrochemical synthesis of chlorine from seawater electrocatalysis.