Water-sprouted, plasma-enhanced Ni-Co phospho-nitride nanosheets boost electrocatalytic hydrogen and oxygen evolution

Chemical waste-free, in situ synthesis of customized earth-abundant-metal based catalysts for high-efficiency water splitting still remains a formidable challenge. Here, Ni-Co hydroxide nanosheets (NCHS) are sprouted from Ni-Co foam (NCF) using an eco-friendly, pure-water-based method, and then are phosphorized and nitrided in N 2 + P plasmas. The resulting N-doped Ni-Co phosphide catalyst (N-NiCoP x /NCF) exhibits excellent electrocatalytic performance, heralded by the low overpotentials of N-NiCoP x /NCF for generating a current density of 10 and 400 mA cm −2 ( j 10 and j 400 ) in 1 M KOH of only 23 and 191 mV for the hydrogen evolution reaction (HER), and 298 and 410 mV for oxygen evolution reaction (OER), as well as by the low decay of high current density ( j 100 ) in the HER (6.02%) and OER (3.07%) processes for 100 h. Ab inito numerical simulations confirm that Co atom bonded with N represents the active center for overall water splitting.