SILD-preparation of nanostructured Rux0-RuO2•nH2O thin films: Effect of deposition cycles on electrocatalytic properties

Ru-x(0)-RuO2 center dot nH(2)O nanocomposite thin films have been synthesized on the surface of nickel through facile and precise Successive Ionic Layers Deposition (SILD) for the first time. Aqueous solutions of RuCl3 and NaBH4 were used as reagents for the synthesis. It is shown that the thin films synthesized as a result of 10-60 SILD cycles are formed by flat globules of a hydrated Ru (IV) oxide with a planar size of about 100 nm and Ru-0 nanoparticles with a size of 5-9 nm. Based on the experimental data obtained, schemes are designed of the sequence of chemical reactions occurring on the surface of the substrate during synthesis. A study of the electrochemical properties of the thin films showed that nickel foam electrodes with Ru-x(0)-RuO2 center dot nH(2)O layers synthesized as a result of 10, 20, 40 and 60 SILD cycles exhibited overpotential values equal to 49, 36, 32 and 31 mV at 10 mA/ cm(2) and Tafel slope values equal to 75.4, 65.2, 54.5 and 53.9 mV/dec, respectively, in hydrogen evolution reaction during water electrolysis in alkaline medium. A comparison of these values indicates that the values of the overpotential and Tafel slope for the samples synthesized after 40 and 60 SILD cycles are approximately equal, but the sample obtained after 40 SILD cycles contains a smaller amount of the electrocatalyst, which makes it possible to choose the latter sample as optimal in terms of composition and electrocatalytic properties. It is important that the overpotential value for the sample increased only by 4 mV after 500 potential cycling, which indicates a relatively high stability of its properties.