A superhydrophilic NiFe electrode for industrial alkaline water electrolysis

NiFe-based materials are among the most promising alkaline oxygen evolution reaction (OER) catalysts because of their high intrinsic activities and abundance. Although many advanced NiFe-based catalysts have been developed, few exhibit simultaneous high ac-tivity, stability, good mass transfer, and cost-effective large-scale preparation. Further-more, NiFe-based catalysts have rarely been studied in alkaline water electrolyzers (AWE) where the catalysts work under a large current density in an alkaline electrolyte at high temperatures and high concentrations with tight assembly pressure. This study success-fully developes robust and highly active NiFe nanocone array (NA) catalysts that exhibit both fast and cost-effective mass production capabilities. Benefiting from the in situ -formed OER-active NiFe layered double hydroxide (LDH) and the superhydrophilic structure-induced fast mass transfer, the optimized NiFe NA sample presentes a low OER overpotential of 269 mV at 500 mA cm-2 in a 30 wt% KOH solution. The NiFe core-NiFe LDH shell structure and metallic bond between NiFe nanocones and the substrate are crucial for enabling the NiFe electrode to maintain a minimal potential increase of only 4% even after 250 h of testing at 500 mA cm-2 in a 30 wt% KOH solution. Moreover, the AWE using NiFe NA anodes and NiMo cathodes (NiFe//NiMo) works stably at 500 mA cm-2 under 80 degrees C in 30 wt% KOH solution and presents a power energy consumption of 4.0 kWh Nm-3 H2, much lower than that of the Ni mesh//Ni mesh counterpart and most commercial AWEs. This study, for the first time, evaluates the performance of NiFe electrodes in AWE and dem-onstrates their industrial application prospects in alkaline water electrolysis.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.