Optimization of Mixed Metal Oxide Electrodes for Chlorine Generation: An Alternative to Conventional Platinum Group Metal Materials

Dimensionally stable anodes (DSAs) are widely used for the free chlorine evolution reaction (CER); however, their reliance on expensive platinum group metals limits their widespread adoption. This cost barrier has driven the search for alternative materials that are both effective and affordable. Cobalt antimonate (CoSb_xO_y) has been identified as a suitable low-cost and effective alternative for CER, but the synthesis parameters that maximize the Faradaic efficiency (FE) have not been elucidated. The FE of an electrode is influenced by its material properties, which are affected by the synthesis conditions. A factorial design study was used to investigate the effects of electrodeposition potential, charge, and the Sb:Co molar ratio of the plating solution on the CER for CoSb_xO_y electrodes; XRD, XPS, SEM-EDS, and SECM were used to analyze electrode composition. At a deposition potential of -1.005 V_Ag/AgCl, 2.5 mAh charge, and 4.28 Sb:Co, the greatest FE was achieved. Electrode surface morphology was likely the driving factor for maximizing the FE, which may be attributed to the rate of bubble liberation from the anode surface. In dilute chloride solutions at neutral pH, CoSb_xO_y anodes exhibited high stability and comparable FE to conventional Ru/Ir electrodes, highlighting their potential as a durable and cost-effective alternative.