Fe‐Regulated Amorphous‐Crystal Ni(Fe)P2 Nanosheets Coupled with Ru Powerfully Drive Seawater Splitting at Large Current Density

Water electrolysis is an ideal method for industrial green hydrogen production. However, due to increasing scarcity of freshwater, it is inevitable to develop advanced catalysts for electrolyzing seawater especially at large current density. This work reports a unique Ru nanocrystal coupled amorphous-crystal Ni(Fe)P2 nanosheet bifunctional catalyst (Ru-Ni(Fe)P2 /NF), caused by partial substitution of Fe to Ni atoms in Ni(Fe)P2 , and explores its electrocatalytic mechanism by density functional theory (DFT) calculations. Owing to high electrical conductivity of crystalline phases, unsaturated coordination of amorphous phases, and couple of Ru species, Ru-Ni(Fe)P2 /NF only requires overpotentials of 375/295 and 520/361 mV to drive a large current density of 1 A cm-2 for oxygen/hydrogen evolution reaction (OER/HER) in alkaline water/seawater, respectively, significantly outperforming commercial Pt/C/NF and RuO2 /NF catalysts. In addition, it maintains stable performance at large current density of 1 A cm-2 and 600 mA cm-2 for 50 h in alkaline water and seawater, respectively. This work provides a new way for design of catalysts toward industrial-level seawater splitting.