Mechanism insights into H2O2 in situ generation and activation for ciprofloxacin degradation by electro-peroxidation using the ACF@RuO2/Ti cathode

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