Zn-doping defect engineering toward high-performance chlorine evolution reaction and its mechanism study by <i>in situ</i> Raman spectroscopy

Chlorine, a key industrial chemical, is primarily produced through the chlor-alkali process using mixed-metal oxides (MMOs) like dimensionally stable anode (DSA). These anodes face challenges of high overpotential and poor selectivity due to competing oxygen evolution reaction (OER) pathways. This work presents a Zn-doped, defect-engineered RuTiSnZnO<em>_x</em>&nbsp;catalyst on Ti foam to address these issues. The introduction of low-valence Zn creates lattice defects and induces a charge-deficient state at Ru sites. Critically, <em>in-situ</em>&nbsp;electrochemical Raman spectroscopy revealed that this Zn doping facilitates a decisive shift in the key reaction intermediate from Ru-O-Cl to Ru-Cl. This change in the intermediate species directly suppresses the competing OER pathway, thereby enhancing chlorine evolution reaction (CER)&nbsp;selectivity. The catalyst achieves a remarkably low overpotential of 45 mV at 10 mA·cm^–²&nbsp;and exhibits excellent stability with only 13 mV decay after 1000 hours of operation at 100 mA·cm^–². Density functional theory (DFT) calculations further demonstrate that Zn incorporation optimizes the electronic structure by shifting the Ru d-band center closer to the Fermi level. This study elucidates how defect engineering through doping can selectively modulate reaction intermediates, providing a new strategy for developing high-performance, cost-effective CER electrocatalysts.