Electrosynthesis of Neutral H ₂ O ₂ Solution from O ₂ and Water at a Mixed Carbon Cathode Using an Exposed Solid-Polymer-Electrolyte Electrolysis Cell

An improved solid-polymer-electrolyte (SPE) electrolysis method was applied for direct electrosynthesis of neutral H 2 O 2 solution from O 2 and water. The exposure of a cathode prepared from activated carbon (AC), vapor-grown carbon fiber (VGCF), and polytetrafluoroethylene (PTFE) in the O 2 stream was essential for the electrosynthesis of the neutral H 2 O 2 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 H 2 O 2 formation. The active site of the reduction of O 2 was characterized using TPD-Mass and FT-IR techniques; then, the concentration of phenol groups on the AC surface corresponded to the H 2 O 2 formation. The reaction mechanism was proposed that O 2 electrochemically reduced to HO 2 • at the active site of the phenol groups on the AC and in which HO 2 • immediately reduced to H 2 O 2 or disproportioned to H 2 O 2 on the VGCF surface.