Drinking Water Purification by Electrosynthesis of Hydrogen Peroxide in a Power‐Producing PEM Fuel Cell

Abstract The industrial anthraquinone auto‐oxidation process produces most of the world’s supply of hydrogen peroxide. For applications that require small amounts of H 2 O 2 or have economically difficult transportation means, an alternate, on‐site H 2 O 2 production method is needed. Advanced drinking water purification technologies use neutral‐pH H 2 O 2 in combination with UV treatment to reach the desired water purity targets. To produce neutral H 2 O 2 on‐site and on‐demand for drinking water purification, the electroreduction of oxygen at the cathode of a proton exchange membrane (PEM) fuel cell operated in either electrolysis (power consuming) or fuel cell (power generating) mode could be a possible solution. The work presented here focuses on the H 2 /O 2 fuel cell mode to produce H 2 O 2 . The fuel cell reactor is operated with a continuous flow of carrier water through the cathode to remove the product H 2 O 2 . The impact of the cobalt–carbon composite cathode catalyst loading, Teflon content in the cathode gas diffusion layer, and cathode carrier water flowrate on the production of H 2 O 2 are examined. H 2 O 2 production rates of up to 200 μmol h −1 cm geometric −2 are achieved using a continuous flow of carrier water operating at 30 % current efficiency. Operation times of more than 24 h have shown consistent H 2 O 2 and power production, with no degradation of the cobalt catalyst.