Electrogeneration of H2O2 on a composite acetylene black–PTFE cathode consisting of a sheet active core and a dampproof coating

•We fabricated a composite cathode comprising an active core and a dampproof coating.•The cathode had a 108 mA cm−2 of optimal working current and high current efficiency.•The cathode generated H2O2 highly effectively until–3.9 V vs. SCE cathode potential.•The cathode's 54.2 mg cm−2 h−1 of H2O2 production rate was the max. reported so far.•The mechanism was debated from hydrophile–hydrophobe balance on the cathode surface.

A composite acetylene black–PTFE cathode consisting of a sheet active core and a dampproof coating that mainly set up a hydrophile–hydrophobe balance on the cathode surface has been fabricated. The H2O2 was electrogenerated and the main factors affecting the H2O2 yield of the cathode were investigated using a three–electrode undivided cell fed with air as O2 source in Na2SO4 solution of 0.05 M. The experimental results showed that: (1) at the hydrophile–hydrophobe balance, the cathode could utilize not only O2 dissolved in the electrolyte but also O2 in air bubbles as O2 source for the electrogeneration of H2O2, which improved the O2 utilization and, as a result, increased the H2O2 yield; (2) the composite cathode with an optimal working current density of 108 mA cm−2 had a much higher current carrying capacity than the cathode without coating with an optimal working current density of 24 mA cm−2; (3) at the optimal current density of 108 mA cm−2 and pH 3 through 2.5 hour of electrolysis, the accumulation of H2O2 reached 677.5 mg L−1 with a H2O2 production rate of 54.2 mg cm−2 h−1 that was the maximum reported so far, a current efficiency of 79.1% and energy consumption of 27.5 kWh kg−1; (4) the cathode could electrogenerated H2O2 highly effectively until the cathode potential reached–3.9 V vs. SCE; (5) the dampproof coating could inhibit effectively the electrowetting of the cathode surface, and, as a result, increased greatly the useful life of the composite cathode.