Benchmarking accessible electrode materials for electrochemical sodium hypochlorite production

Electrochemical generation of sodium hypochlorite (NaOCl) from sodium chloride (NaCl) solutions provides a practical route for on-site disinfectant production in water treatment systems. However, meaningful comparison among electrode materials remains challenging because many studies employ different reactor configurations and operating conditions. In this work, five accessible non-dimensionally stable anode (non-DSA) materials, aluminum (Al), copper (Cu), graphite, stainless steel (SS), and platinum (Pt), were evaluated under identical electrolysis conditions in an undivided, stirred batch cell containing 20 g L −1 NaCl at near-neutral pH. Electrode spacing (4–10 cm) and applied voltage (6–12 V) were systematically varied, and free chlorine accumulation was quantified by iodometric titration over 40 min. Reducing the electrode spacing from 10 to 8 cm increased free chlorine formation by reducing ohmic losses and improving current delivery. Graphite produced the highest free chlorine concentrations and Faradaic efficiencies, whereas aluminum and copper showed lower net accumulation due to electrode instability and catalytic hypochlorite decomposition. Platinum sustained the highest current densities but comparatively low Faradaic efficiencies, indicating that increasing current alone does not guarantee higher net free chlorine accumulation under near-neutral conditions. These results provide a controlled benchmarking dataset for evaluating low-cost electrode materials in decentralized electrochlorination systems.