Intermediate-Temperature Electrolysis: Electrode Microstructure and Chemistries

Hydrogen from water electrolysis is essential to energy and industrial decarbonization. Beyond being a carbon-neutral fuel to stabilize the intermittent nature of the renewable grid, hydrogen also plays a key role in manufacturing including ammonia and steel production. Intermediate-temperature water electrolysis (>200 °C) has several advantages. First, the thermodynamic requirement for water splitting decreases as temperature increases. Second, reaction kinetics are more facile at higher temperatures. We present water electrolysis using an intermediate-temperature solid acid electrolysis cells (SAECs), with CsH 2 PO 4 (CDP) as an electrolyte. Inspired by Fujiwara et al., whose work demonstrated water electrolysis in SAEC 1 , we extend upon their work to understand the role of electrode materials on stability and efficiency. We analyze the microstructure of post-electrolysis SAFCs to understand the role of temperature and electrode composition on the degradation. We focus on the reaction kinetics of the oxygen evolution reaction (OER) on the anode and present the challenges that must be overcome by future materials. (1) Fujiwara, N.; Nagase, H.; Tada, S.; Kikuchi, R. Hydrogen Production by Steam Electrolysis in Solid Acid Electrolysis Cells. ChemSusChem 2021 , 14 (1), 417–427. https://doi.org/10.1002/cssc.202002281.