Iridium-cobalt mixed oxide electrode for efficient chlorine evolution in dilute chloride solutions

In wastewater treatment, the dimensionally stable anodes (DSAs) based on costly metals are currently being used for electrochlorination due to their superb chlorine evolution reaction (CER) performance. However, owing to their low OER overpotential, DSAs show poor current efficiency for CER in dilute chloride solutions (< 50 mM), which are common wastewater conditions. Therefore, this study aimed to fabricate a novel anode for efficient chlorine evolution in dilute chloride solutions. To control the OER overpotential, cobalt oxide was selected as an electrode material and iridium was added as a cocatalyst with a small content (< 3% atomic percent) to improve stability. Iridium-cobalt mixed oxide (ICO) electrode showed a sevenfold improvement in CER efficiency (15%) in 1 mM NaCl concentration compared to pristine IrO2 (2%). In addition, above a 50 mM NaCl concentration, ICO exhibited an excellent CER efficiency close to unity. Furthermore, superiority as a CER anode was also demonstrated with high stability (> 200 h) in the accelerated stability test (0.5 M H2SO4 solution at 0.1 A cm(-2)) as well as superior ammonium degradation performance in dilute aqueous conditions. These results suggest that ICO can be a promising anode with its high CER efficiency, low cost, and notable stability.& nbsp;(C) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, a novel anode material for efficient chlorine evolution in dilute chloride solutions was fabricated. The iridium-cobalt mixed oxide (ICO) electrode exhibited a significantly improved chlorine evolution reaction (CER) efficiency compared to the pristine IrO2 electrode. ICO also demonstrated excellent stability and ammonium degradation performance. These results suggest that ICO is a promising and cost-effective anode material for various applications.