Decomposition of Hydrogen Bromide or Iodide by Gas Phase Electrolysis

Abstract

Abstract Gas phase electrolysis of HBr or HI was studied by using a fuel-cell-type electrolyzer provided with graphite gas diffusion electrodes and liquid film electrolyte of H3PO4. Current efficiency 100% may be achieved at decomposition voltages of 0.73 V (at 100 mA cm−2 and 150 °C) for HBr and 0.28 V (at 100 mA cm−2 and 145 °C) for HI. Both bromine and iodine produced may smoothly be evolved out of the anode in the gas or liquid form without being dissolved into the electrolyte H3PO4, causing no trouble on the separation of products. This electrolytic method may be incorporated in the bromine or iodine cycles for thermochemical hydrogen production to constitute an effective hybrid system.