Electrodeposition at Highly Negative Potentials of an Iron‐Cobalt Oxide Catalyst for Use in Electrochemical Water Splitting

Earth‐abundant transition metal‐based catalysts have been extensively investigated for their applicability in water electrolysers to enable overall water splitting to produce clean hydrogen and oxygen. In this study a Fe−Co based catalyst is electrodeposited in 30 seconds under vigorous hydrogen evolution conditions to produce a high surface area material that is active for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). This catalyst can achieve high current densities of 600 mAcm−2 at an applied potential of 1.6 V (vs RHE) in 1 M NaOH with a Tafel slope value of 48 mV dec−1 for the OER. In addition, the HER can be facilitated at current densities as high as 400 mA cm−2 due to the large surface area of the material. The materials were found to be predominantly amorphous but did contain crystalline regions of CoFe2O4 which became more evident after the OER indicating interesting compositional and structural changes that occur to the catalyst after an electrocatalytic reaction. This rapid method of creating a bimetallic oxide electrode for both the HER and OER could possibly be adopted to other bimetallic oxide systems suitable for electrochemical water splitting. Electrodeposition of FeCo oxide type electrocatalysts at highly negative potentials results in the formation of a high‐surface‐area electrocatalyst that is active for both the oxygen evolution reaction and the hydrogen evolution reaction under alkaline conditions. @QUTSciEng #watersplitting