Robust and efficient Iron-Based electrodes for hydrogen production from seawater at high current density above 1000 mA cm⁻²

The implementation of cheap iron-based catalysts for seawater electrolysis at high- current–density offers an economical and sustainable solution for industrial hydrogen production in near future. However, Fe-based electrodes suffer from poor intrinsic activity and corrosion resistance in seawater, resulting in unsatisfactory seawater splitting performance. Here, we reported the scale-up fabrication of whole-Fe-based electrodes (NiFe-X (X = O, P) NAs/Fe foam) by facile soaking-phosphating. Surface active layers exhibit enhanced corrosion resistance compared to bare Fe foam, and trace Ni modification lowers reaction energy barriers of cathodic NiFeP and in-situ generated anodic NiFeOOH, respectively. Thus, NiFe-P||NiFe-O pair only requires 1.93 V to deliver 3000 mA cm⁻² at 6 M KOH, 60 °C for overall seawater splitting, and works stably for 200 h at 1000 mA cm⁻². Furthermore, NiFe-X (X = O, P) NAs/Fe foam show impressive adaptation to fresh water/tap water/seawater and all kinds of renewable energies, presenting excellent flexibility for various environmental applications and scenarios.