Electrosynthesis of Neutral H₂O₂ Solution from O₂ and Water at a Mixed Carbon Cathode Using an Exposed Solid-Polymer-Electrolyte Electrolysis Cell

Abstract

An improved solid-polymer-electrolyte (SPE) electrolysis method was applied for direct electrosynthesis of neutral H2O2 solution from O2 and water. The exposure of a cathode prepared from activated carbon (AC), vapor-grown carbon fiber (VGCF), and polytetrafluoroethylene (PTFE) in the O2 stream was essential for the electrosynthesis of the neutral H2O2 solution (Exp-SPE method). The oxidation treatment of the AC surface and the modification of the cathode using a Nafion solution enhanced the electrochemical activity of the cathode for the neutral H2O2 formation. The active site of the reduction of O2 was characterized using TPD-Mass and FT-IR techniques; then, the concentration of phenol groups on the AC surface corresponded to the H2O2 formation. The reaction mechanism was proposed that O2 electrochemically reduced to HO2• at the active site of the phenol groups on the AC and in which HO2• immediately reduced to H2O2 or disproportioned to H2O2 on the VGCF surface.