Surface-interface functionalized stainless steel enables supported NiFe-(oxy)hydroxides to operate robustly at 1 A cm−2

The stainless steel (SS) has big potential to become a valid catalytic substrate to supported the NiFe-(oxy)hydroxides (NiFe-OxHy) for alkaline water electrolysis. Here, a surface-interface functionalized strategy is proposed to fabricate supported NiFe-OxHy on andic etching SS (SS-A) with intermediate layer of amorphous spinel-like oxides (FeNiOx/SS-A). The synthesized NiFe/FeNiOx/SS-A requires an overpotential of only 265 mV to yield current densities of 100 mA cm−2 and gives a low Tafel slope of 36 mV dec−1. After operated under the current density of 100 mA cm−2 for 60 h, it without changed in surface main phase of (oxy)hydroxide and performed well in inhibiting the dissolution of Fe. More interestingly, it also exhibited the ability to self-healing the surface cracks. The overall water-splitting assembled by NiFe/FeNiOx/SS-A and Pt can run stably at an ultra-high current density of 1 A cm−2, which is the most stable NiFe-OxHy electrode reported so far. The strategy proposed here provides a promising opportunity for preparing efficient and robust NiFe-OxHy catalysts to better align with commercial applications.