Atomically Dispersed Ru-doped Ti₄O₇ Electrocatalysts for Chlorine Evolution Reaction with a Universal Activity

Chlorine has been supplied by the chlor-alkali process that deploys dimensionally stable anodes (DSAs) for the electrochemical chlorine evolution reaction (ClER). The paramount bottlenecks have been ascribed to an intensive usage of precious elements and inevitable competition with the oxygen evolution reaction. Herein, a unique case of Ru²⁺-O₄ active motifs anchored on Magnéli Ti₄O₇ (Ru-Ti₄O₇) via a straightforward wet impregnation and mild annealing is reported. The Ru-Ti₄O₇ performs radically active ClER with minimal deployment of Ru (0.13 wt%), both in 5 m NaCl (pH 2.3) and 0.1 m NaCl (pH 6.5) electrolytes. Scanning electrochemical microscopy demonstrates superior ClER selectivity on Ru-Ti₄O₇ compared to the DSA. Operando X-ray absorption spectroscopy and density functional theory calculations reveal a universally active ClER (over a wide range of pH and [Cl⁻]), through a direct adsorption of Cl⁻ on Ru²⁺-O₄ sites as the most plausible pathway, together with stabilized ClO* at low [Cl⁻] and high pH.