Constructing electrospun spinel NiFe2O4 nanofibers decorated with palladium ions as nanosheets heterostructure: boosting electrocatalytic activity of HER in alkaline water electrolysis

Abstract

The development of efficient electrocatalysts for the water splitting process and understanding their fundamental catalytic mechanisms are highly essential to achieving high performance in energy conversion technologies. Herein, we have synthesised spinel nickel ferrite nanofibers (NiFe₂O₄-NFs) via an electrospinning (ES) method followed by a carbonization process. The resultant fiber was subjected to electrocatalytic water splitting reactions in alkaline medium. The catalytic efficiency of the NiFe₂O₄-NFs in OER was highly satisfactory. But it is not high enough to catalyse the HER process. Hence, palladium ions were decorated as nanosheets on NiFe₂O₄-NFs as a heterostructure to improve the catalytic efficiency for HER. Density functional theory (DFT) confirms that the addition of palladium to NiFe₂O₄-NFs helps to reduce the effect of catalyst poisoning and improve the efficiency of the catalyst. In an alkaline hybrid electrolyser, the required cell voltage was observed as 1.51 V at a fixed current density of 10 mA cm⁻².