Anion intercalated nickel iron hydrogen phosphate hydrate for full water splitting application

Exploration of effective and earth abundant electrocatalysts is essential for various renewable energy conversion technologies. The electrolysis of water into oxygen and hydrogen is one of the most promising methods to produce clean hydrogen fuel from electricity supplied by renewable energy sources. However, the high cost and rarity of conventional noble metal−based catalysts limit their practical applications. Hence, anion (NO3−) intercalated iron hydrogen phosphate supported on nickel foam (NiFeHP/NF) is fabricated for the first time by the combined hydrothermal and followed electrodeposition methods. The anion intercalation modifies the surface and electronic structure, thereby enhancing the oxygen evolution reaction (OER) and hydrogen evolution rection (HER). The NO3− intercalation increased the wettability of the catalyst and the contact between the electrode and electrolyte, thereby improving the mass transfer capability. The electrochemical analysis demonstrates that the NO3− intercalated for about 20 min over the NiFeHP/NF catalyst (NiFeHP-6) needs an overpotential of 280 and 265 mV only at a high current density of 100 mA cm−2 to drive OER and HER, respectively, in an alkaline 1M KOH electrolyte and outperforms the benchmark RuO2 catalyst fabricated on NF in OER.