Design of CoSbyOx/Ti electrocatalyst via facile thermal decomposition method for durable and high temperature chlorine evolution reaction in acidic media

Abstract

Developing stable and cost-effective electrodes for the anode compartment of chlor-alkali process to drive the chlorine evolution reaction (CER) has remained as a challenge. This study introduces CoSbyOx/Ti as a durable and non-precious anode electrocatalyst synthesized via facile and scalable thermal decomposition method. This novel electrode permanently conducts CER for 240 h under 100 mA.cm−2 at 70 °C in 4 M NaCl (pH=2) with an overpotential of only 498 mV and a high selectivity of 92.2 % toward CER. From XRD results, crystalline CoSb2O6 forms above 600 °C and acts as active and stable phase during CER. From XPS analysis, a combination of Co3+ and Co2+ forms on the surface of the electrode; the content of Co3+ species increases after CER which can reduce structural defects and hence improve the stability of the structure. We further shed more light on the degradation mechanism of this type of electrodes by performing additional 240 h durability test under accelerated condition of 1000 mA.cm−2. Observations indicate a failure mechanism that is probably a combination of deactivation of the electrode and catalyst detachment in accelerated conditions.