Successive ionic layer deposition of NiP_x nanolayers on the surface of nickel foam and their electrocatalytic properties for oxygen evolution reaction upon water splitting in alkaline medium

Synthetic conditions of obtaining nickel phosphide nanolayers by Successive Ionic Layer Deposition (SILD) method are described. The samples were characterized via XRD, SEM, EDX and XPS. We demonstrate that NiP_x amorphous nanolayers are formed on the surface and they include oxygen atoms forming Ni-OH and P-OH groups. Investigation of the electrocatalytic properties showed high activity of oxygen release during the electrolysis of water in the alkaline medium. Moreover, it was shown that the characteristics of such electrocatalysts changed in the series of samples synthesized after different number of SILD cycles. The best electrocatalytic properties belong to the sample which was acquired as a result of 10 cycles. It is characterized by overpotential values of 305, 390 and 418 mV, at currents of 20, 50 and 100 mA, respectively, as well as Tafel slope of 75 mV/dec. On the basis of the experimental results, it is suggested that the SILD method can be used to synthesize a wide range of nanocomposites that have improved electrocatalytic properties.