Durability of the FeNi3@Ni Material Designed for Water Electrolysis Enhanced by High Frequency Alternating Magnetic Field

This work aims to mimic in "model" conditions the influence of an electrochemical environment associated with an alternating magnetic field (AMF) exposure on FeNi3@Ni nanoparticles. These have been designed to perform alkaline water electrolysis (AWE) enhanced by AMF, the latter allowing to heat locally the catalyst by hysteresis and eddy current losses. The (electro)chemical effect of the aggressive alkaline environment (reducing/oxidizing potential and atmosphere) and of the temperature (mimicking the AMF-induced heating) are addressed by using dedicated (in situ) techniques. First, durability tests carried out in a rotating disk electrode setup without AMF are presented; they show the poor hydrogen evolution reaction durability but an acceptable oxygen evolution reaction durability of this material. Complementary identical location (IL) transmission electron microscopy enables us to track the associated morphology/composition changes experienced by the catalysts in these conditions. Second, IL scanning electron microscopy unveils the fate of electrodes having operated in AMF-enhanced AWE. Third, the influence of a reductive/oxidant atmosphere, combined with a high temperature exposition (up to 600 °C), indicates that this material undergoes crystallographic changes, which may alter the electrochemical activity in long-term experiments with repetitive AMF exposures. The combination of these tests provides insights into the possible long-term durability of this catalytic material in AMF-enhanced AWE.