Please use this identifier to cite or link to this item: https://physrep.ff.bg.ac.rs/handle/123456789/1340
Title: Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance
Authors: Krstajić Pajić, Mila N
Dobrota, Ana S
Mazare, Anca
Đurđić, Slađana
Hwang, Imgon
Skorodumova, Natalia V
Manojlović, Dragan
Vasilić, Rastko 
Pašti, Igor A
Schmuki, Patrik
Lačnjevac, Uroš
Keywords: density functional theory;galvanic deposition;mass activity;metal-support interactions;platinum group metals
Issue Date: 5-Jul-2023
Journal: ACS applied materials & interfaces
Abstract: 
Efficient cathodes for the hydrogen evolution reaction (HER) in acidic water electrolysis rely on the use of expensive platinum group metals (PGMs). However, to achieve economically viable operation, both the content of PGMs must be reduced and their intrinsically strong H adsorption mitigated. Herein, we show that the surface effects of hydrogenated TiO2 nanotube (TNT) arrays can make osmium, a so far less-explored PGM, a highly active HER electrocatalyst. These defect-rich TiO2 nanostructures provide an interactive scaffold for the galvanic deposition of Os particles with modulated adsorption properties. Through systematic investigations, we identify the synthesis conditions (OsCl3 concentration/temperature/reaction time) that yield a progressive improvement in Os deposition rate and mass loading, thereby decreasing the HER overpotential. At the same time, the Os particles deposited by this procedure remain mainly sub-nanometric and entirely cover the inner tube walls. An optimally balanced Os@TNT composite prepared at 3 mM/55 °C/30 min exhibits a record low overpotential (η) of 61 mV at a current density of 100 mA cm-2, a high mass activity of 20.8 A mgOs-1 at 80 mV, and a stable performance in an acidic medium. Density functional theory calculations indicate the existence of strong interactions between the hydrogenated TiO2 surface and small Os clusters, which may weaken the Os-H* binding strength and thus boost the intrinsic HER activity of Os centers. The results presented in this study offer new directions for the fabrication of cost-effective PGM-based catalysts and a better understanding of the synergistic electronic interactions at the PGM|TiO2 interface.
URI: https://physrep.ff.bg.ac.rs/handle/123456789/1340
ISSN: 19448244
DOI: 10.1021/acsami.3c04498
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