(187g) Novel Synthesis of Maghemite Nanospheres on Nickel Foam As a Bifunctional Electrocatalyst for Alkaline Water Splitting

Hydrogen has shown promise as the future of zero-carbon energy storage. However, partly due to the cost of noble metal electrocatalysts for Alkaline Water Splitting (AWS), most hydrogen production continues to rely on fossil fuels. So, in recent years, tremendous effort has been dedicated to alternatives; however, many are hindered by synthesis procedures that are not operable at large scales and materials not globally accessible. Given these considerations, this work demonstrates the facile, industrially viable synthesis of an inexpensive, novel maghemite nanosphere electrode to increase the global accessibility of green hydrogen. The electrocatalyst was prepared via a layer-precursor method involving the aerobic transformation of an oxyhydroxide precursor using a novel hydrogen thermal AHC process and the oxidation of a magnetite intermediate. The electrode presented excellent activity in a KOH medium with low overpotentials, outperforming the standard RuO₂ noble metal electrode at high current densities in the Oxygen Evolution Reaction (OER) due to the effect of cation vacancies on anion intermediate binding energy. The electrochemically active surface area (ECSA) of the electrocatalyst was increased by 274% and 335% for the Hydrogen Evolution Reaction (HER) and the OER, respectively, reducing the bubble problem and thus dramatically increasing efficiency. Furthermore, the synthesized electrocatalyst demonstrated better stability over 120 hours than RuO₂ and Pt. Overall, this precursor method exhibits potential to be generalized to the synthesis of other transition metal oxide-based nanostructures for a wide variety of material applications. Similarly, the AHC process to produce magnetite from iron hydroxide in an aerobic environment has numerous applications in biomedical nanotechnology.