3D self-supported Fe O P film on nickel foam as a highly active bifunctional electrocatalyst for urea-assisted overall water splitting

Abstract Replacement of oxygen evolution (OER) by the more readily oxidized urea is considered to be a promising strategy for electrocatalytic water-splitting. In this work, we report a Fe O P film on nickel foam (Fe O P/NF) via atomic layer deposition (ALD) of iron oxide and a subsequent phosphonation process, which acts as a superior bifunctional electrocatalyst for both urea evolution reaction (UOR) and hydrogen evolution reaction (HER). Benefiting from the synergetic effects, the Fe O P/NF exhibits a low potential of 1.34 V (vs. RHE) at 10 mA cm−2 and a low Tafel slope of 57.2 mV dec−1 for UOR. Combined with the high HER activity of Fe O P/NF, the urea-based overall water splitting can be performed with an low voltage of 1.43 V to deliver 10 mA cm−2 in 1.0 M KOH with 0.5 M urea, which is 200 mV lower than that for pure water splitting.