The Solid-Polymer-Electrolyte Coelectrolysis of O 2 and Water to Pure 26 wt % H 2 O 2 Aqueous Solutions with 81% Current Efficiency

Hydrogen peroxide is one of the essential chemicals in the industry. The H 2 O 2 manufacture process using the anthraquinone method has a serious disadvantage of a large amount of energy consumption. Direct synthesis of pure H 2 O 2 aqueous solutions with an 8.4 mol L –1 (26.2 wt %) concentration and 81% current efficiency was achieved by coelectrolysis of O 2 and water by solid-polymer-electrolyte electrolysis. The cathode catalyst used was Ketjen black (KB)-supported 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (Co-TPP), which was activated in inert gas at 1023 K, abbreviated as Co-TPP/KB(1023K), and the anode was Ti-mesh-supported IrOx. The active site of the Co-TPP/KB(1023K) catalyst (0.05 wt % Co loading) was confirmed as CoN 2 C x by extended X-ray absorption fine structure (EXAFS). Essential factors for the production of H 2 O 2 were revealed as (i) the effects of washout by water diffused from the anode compartment on the H 2 O 2 formation at the cathode, (ii) water diffusion through the vehicle mechanism induced by the anode without ionomer modification, and (iii) the increase in activity of O 2 on the cathode under pressure conditions of 11∼21 atm of pure O 2 .