Direct successive ionic layer deposition of nanoscale iridium and tin oxide on titanium surface for electrocatalytic application in oxygen evolution reaction during water electrolysis in acidic medium

In this paper, we propose a novel promising route for the direct synthesis of nanoscale iridium and tin oxide nanolayers by a successive ionic layer deposition method (SILD). The precursors for the synthesis included an aqueous solution of SnF2 with an equilibrium pH value and the colloidal solution of IrOx∙nH2O nanoparticles and Na2[Ir(OH)6] mixture with pH = 10.5, obtained by the alkaline hydrolysis of the H2IrCl6 solution. The synthesized nanoscale oxide exhibited electrocatalytic properties in the oxygen evolution reaction (OER) upon water splitting in the acidic medium. A series of samples were obtained, synthesized as a result of 10, 30, and 50 SILD processing cycles. It was found that the films obtained as a result of 30 SILD cycles and heated in argon at a temperature of 300 °C had the best electrocatalytic properties in the reaction of oxygen evolution in the HClO4 solution. For these films, the overpotential value at a current density of 10 mA/cm2 was 288 mV and the Tafel coefficient value totaled 56 mV/dec. Investigations by SEM, TEM, EDX, XRD, XPS and FTIR spectroscopy revealed that the samples were built of Ir0.7SnOx∙nH2O amorphous nanoparticles with a size of 10–20 nm. For this kind of electrode, estimation of the specific mass of iridium showed that its amount is about 0.02 mg/cm2. It is suggested that the new synthetic method may serve as the basis for creating a wide range of coatings for electrodes in electrochemical devices, including electrochemical sensors, electrical stimulators, electrochromic devices, etc. [Display omitted] •A new route for the direct synthesis of IrxSnOy∙nH2O nanolayers using the SILD method has been proposed.•A model of IrxSnOy∙nH2O nanolayers formation has been suggested.•Ir0.7SnOx∙nH2O nanolayers demonstrate a low overpotential value in the OER during water electrolysis in the acidic medium.