Lawrence Berkeley National Laboratory

Two simple processes for enhancing liquid alkaline water electrolyzer performance are demonstrated. Both enhance 3D Ni electrodes by introducing a micron-scale rough structure throughout the bulk of the electrode. Oxidation/reduction relies on a simple thermal treatment cycle to create surface roughening through the volumetric expansion during NiO formation and volume contraction during reduction back to Ni metal. Catalyst infiltration introduces a washcoat of additional metal particles throughout the electrode, by flooding the electrode with catalyst precursor and converting it to micron-scale particles via a reducing thermal treatment. The largest improvement in performance (211 mV at 1.8 A cm−2) is observed for infiltrated NiFe-3x catalyst. For Fe-free Ni-only electrodes, oxidation/reduction provides a larger improvement (157 mV at 1.8 A cm−2) than infiltrated Ni-3X (106 mV at 1.8 A cm−2). For both processes, the observed electrode surface structure and performance is quite sensitive to the thermal treatment temperature.