Recent advances in electrocatalytic chloride oxidation for chlorine gas production

Abstract

Chlorine gas is one of the most basic chemicals produced through electrolysis of brine solution and is a key raw material in many areas of industrial chemistry. In the past half a century, the dimensionally stable anode (DSA) made of RuO₂ and TiO₂ coated on the Ti substrate is the most widely used catalytic electrode for chlorine oxidation. However, the drawbacks of the DSA such as high cost, inferior selectivity and detrimental effects on the environment cannot meet the demand of modern industries. Recently, tremendous progress has been achieved in developing low-cost and efficient electrocatalysts for the chlorine evolution reaction (CER). Herein, a concise, but comprehensive and critical review is provided to summarize the recent advances in the field of electrocatalytic CER. First, the history of the chlor-alkali process and the catalytic mechanism of CER are summarized and presented. Then, three categories, namely, noble metal-based, earth-abundant transition-metal-based, and carbon-based metal-free electrocatalysts, are reviewed together with strategies for improving the CER catalytic performance. Lastly, future opportunities in this exciting field are outlined in terms of materials design, structure–performance relationship, technical improvements for the reactor and application scenarios extension.