Electrogeneration of H₂O₂ by graphite felt double coated with polytetrafluoroethylene and polydimethylsiloxane

Efficient and steady electrogeneration of H₂O₂ is a significant step in the Electro-Fenton water treatment process. This study fabricates a polytetrafluoroethylene (PTFE) coated graphite felt cathode with a polydimethylsiloxane (PDMS) damp-proof coating to generate H₂O₂ in a flow-through system without an external oxygen supply. We evaluated the effect of PDMS content, current, flow rate, and pH on H₂O₂ production. PDMS coating inhibits electrowetting to extend the longevity of the modified graphite felt for electrogeneration of H₂O₂. However, increasing PDMS content can decrease H₂O₂ production due to reduction of active sites on the graphite felt. Graphite felt electrodes (surface area = 14.5 cm²) coated with 500 mg of PDMS can generate 10 mg/L of H₂O₂ under a flow rate of 3 mL/min with only 2% production reduction after 24-hour use. This modified graphite felt has better performance in a neutral or alkaline environment than in an acidic condition. Up to 38.5 mg/L of H₂O₂ will be generated at optimum current (120 mA) at the flow rate of 3 mL/min. Increasing the flow rate decreases the concentration of H₂O₂ in the electrolyte but enhances total production after 145 mins.