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

Ni-Co hydroxide nanosheets sprouted from Ni-Co foam (NCF) using pure water, are further phospherized and doped in P + N2 plasmas. N-doped NiCoPx/NCF exhibits high HER (23 and 191 mV) and OER (298 and 410 mV) activity at j10 and j400, as well as ultra-stable HER and OER process with a j100, revealing the promising high-performance non-noble-metal electrocatalyst. [Display omitted] •The Ni-Co hydroxide nanosheets are sprouted from Ni-Co foam using pure water.•The N-doped Ni-Co phosphide is achieved by dry protocol of N2-P RF plasma.•The formed heterointerfaces and N doping rich the active sites of catalyst for water splitting.•The electrocatalytic performances exhibit potential application for industry-scale. 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 N2 + P plasmas. The resulting N-doped Ni-Co phosphide catalyst (N-NiCoPx/NCF) exhibits excellent electrocatalytic performance, heralded by the low overpotentials of N-NiCoPx/NCF for generating a current density of 10 and 400 mA cm−2 (j10 and j400) 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 (j100) 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.