Preparation and application study of nickel-based metal-organic frameworks composite graphite flakes electrode materials for acidic electrolytic oxidized water

Abstract Electrochemical chlorine evolution reaction (CER) is a crucial practical application of electrochemical processes, particularly in the field of electrochemical disinfection. Acidic electrolytic oxidized water (AEOW), an effective electrochemical disinfectant, is produced by electrolyzing a very dilute chlorine solution within an ion-exchange membrane electrolyzer. During this process, hypochlorous acid is formed at the anode through the CER, showcasing significant sterilization activity. Due to the minimal presence of chloride ions, enhancing the selectivity of the electrode for CER is essential to boost the effectiveness of chlorine electrolysis. In addition, oxygen evolution reaction (OER) that occurs in the anode region impedes the electrode material's ability of CER. In this work, we successfully synthesized a nickel-based metal framework composite graphite flake electrode. This electrode demonstrates remarkable selectivity and activity in the context of the CER process, displaying an overpotential of 158.3 mV when a current density of 10 mA cm−2, and the voltage difference recorded between the CER and OER (ΔECER-OER) was found to be 488 mV. The optimal preparation conditions for the preparation of AEOW were explored to produce AEOW and carry out sterilization experiments. The experiments showed that when available chlorine content was 70 mg/L, the sterilization rate was 63.9% in 1 min, 90% in 5 min, and 99.9% in 15 min.