Cobalt oxide (CoOx) coated Ni foam anodes for high temperature (150 °C) and pressure (45 bar) alkaline electrolysis

CoO x -coated Ni foam (CoO x /NF) electrodes are evaluated as anodes for high temperature and pressure (HTP) alkaline electrolysis. The electrodes are tested for the oxygen evolution reaction (OER) from room temperature to 150 °C at 45 bar pressure in 45 wt% KOH and compared with commercially available pristine NF and Inconel-coated NF (Inconel/NF) electrodes. Although the Inconel/NF electrode shows the best performance at 25 °C and 45 bar pressure, the performance of CoO x /NF and Inconel/NF become comparable upon raising the operating temperature to 150 °C. During a long-term (108 h) stability test at 150 °C and 45 bar pressure, the CoO x /NF electrode maintained stable performance, requiring an overpotential of 185 mV at 500 mA cm −2 . In contrast, the Inconel/NF electrode experienced an increase in overpotential from 182 mV to 208 mV after 84 h of operation under identical conditions. The structural and chemical changes in these electrodes were investigated using post-mortem scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), comparing their evolution to that of the fresh electrodes. • Ni foam (NF), CoOx/NF and Inconel/NF electrodes are assessed as anodes for HTP-AE. • Increasing operating temperature reduces the overpotential of the anode. • Low current densities (10–100 mA/cm 2 ) are inadequate to assess electrode stability. • The CoO x /NF electrode showed remarkable activity and stability at 150 °C, 45 bar.