Electrode optimization for efficient hydrogen production using an SO2-depolarized electrolysis cell

The hybrid sulfur (HyS) cycle offers an alternative route to hydrogen and sulfuric acid production using the SO2-depolarized electrolysis (SDE) cell. This work reports the most efficient SDE operation to date at high sulfuric acid concentrations (∼60 wt%) achieved through the optimization of operating conditions and cell components. We observed that open porosity in the porous transport media (PTM) plays a significant role in SDE performance as it enables efficient acid removal from the catalyst layer. The combination of membrane electrode assembly (MEA) components, such as Sulfonated Diels Alder Poly (phenylene) (SDAPP) membranes and electrodes prepared using SGL 29BC PTM, and operating conditions (103.4 kPagauge at 125 °C) yielded electrolysis potentials <700 mV at 500 mA/cm2 and acid concentrations >60 wt%.