Ni-Fe Alloy Nanostructured Electrodes for Water Splitting in Alkaline Electrolyser

ABSTRACT ElectrochemicalhydrogenproducedbywatersplittingisaninterestingenergycarrierwithoutCO 2 emission.Thehighenergyrequiredbyelectrolysersandtheuseofhigh-qualitycatalystsarecertainlythemostrelevantproblemstobesolved.Toovercometheseproblems, In this work, theopportunitiesofferedbytheemploymentof nickel-iron alloy nanostructured electrodes obtained by template electrosynthesis method havebeen are investigated for both hydrogen and oxygen evolution reactions. Such Electrodes consist of nanowire arrays with high surface area that are able to ensures a high electrolytic activity. To obtain different alloy compositions, the concentration of the elements in the deposition baths was is appropriately tuned. Themorphologicalandchemicalcharacterizationshaveshowntheformationofregularanduniformarraysofnanowireswellanchoredtothecurrentcollector.Theexperimentalobtained Results show that the composition of nanowires does not change linearly with the composition of deposition bath but inallthecasesanalysed,theelectrodeswerefoundtobe are richer in Fe. Nanostructured electrodes werestudied are tested as both cathodes and anodes in alkalineconditions,in 30 wt% KOH aqueous solution, at room temperature to determine the best alloy composition. Furthermore,mid-andlong-termstabilitytestswereconductedingalvanostaticcondition. In all electrochemical tests, the electrodes that performed best are those with iron content of 78.95 at%. Particularly, the results are very promising for the oxygen evolution reaction, with a Tafel's slope of 40 mV and a potential of 1.532 V vs. RHE after 6 h at constant current of 50 mA cm−2. Besides, preliminary tests in 0.5 M NaCl alkaline aqueous solution are also reported showing very promising results.