Mechanism insights into H2O2in situ generation and activation for ciprofloxacin degradation by electro-peroxidation using the ACF@RuO2/Ti cathode

Abstract

Electrocatalytic H2O2 production via the two-electron oxygen reduction reaction on the cathode surface plays a crucial role in the electro-peroxidation (EO-H2O2). In this work, the H2O2 generation potential of the EO-H2O2 process using an activated carbon fiber attached RuO2/Ti cathode (ACF@RuO2/Ti) was evaluated by simulation experiments with a high-precision syringe pump. Results shown that the actual average H2O2 accumulation rate reached up to 4.92 mg h−1 cm−2, while more than 95 % of the electrogenerated H2O2 was decomposed quickly. Electron paramagnetic resonance and quenching tests confirmed that the primary oxidant •OH was produced from H2O2 activation by ACF, RuO2 catalyst and their synergistic effect, while RuO2 played dominant role. The production of •OH in the EO-H2O2 process was also confirmed by the degradation and mineralization of antibiotic ciprofloxacin. The characterization results indicated that heterogeneous catalysis of cathode was due to both the pyridinic nitrogen and oxygen-containing groups of ACF, along with RuO2 catalyst on the RuO2/Ti surface. This study provides new insights into the mechanisms of the in situ H2O2 generation and activation in the EO-H2O2 process.