Highly selective electrochemical synthesis of ClO2 from chlorite with Ti4O7 for rapid pollutants degradation and safe disinfection

Industrial synthesis of chlorine dioxide (ClO 2 ) is infrastructure-demanding and presents significant safety and transportation challenges. The electrochemical method, while offering an on-site ClO 2 production alternative, suffers from risky chlorate (ClO 3 − ) generation, even when using a widely-utilized noble metal-based dimensionally stable anode (DSA). In this study, we report that a Ti 4 O 7 anode can efficiently convert chlorite (ClO 2 − , 25 mmol L −1 ) to ClO 2 with an impressive selectivity of 99% at 10 mA cm −2 . Unlike DSA, which generates abundant free hydroxyl radicals (•OH) that over-oxidize ClO 2 − into ClO 3 − via a 2:1 stoichiometry, the Ti 4 O 7 anode confines •OH onto its surface, facilitating selective ClO 2 − oxidation through single-electron transfer reaction. With this novel Ti 4 O 7 anode, a portable ClO 2 gas generator was designed to continuously deliver high-purity and cost-effective ClO 2 at a rate of 3.30 g h −1 with high stability over 5-day operational period, and thus is very promising for rapid water pollutants (sulfamethazine, ciprofloxacin, cephalexin, tetracycline, and carbamazepine) degradation and safe disinfection against pathogens ( E. coli, S. aureus , and AR E. coli ) in minutes with minimal chlorinated byproducts.