Nanotubular TiO x N y -Supported Ir Single Atoms and Clusters as Thin-Film Electrocatalysts for Oxygen Evolution in Acid Media

Luka Suhadolnik; Marjan Bele; Miha Čekada; Primož Jovanovič; Nik Maselj; Anja Lončar; Goran Dražić; Martin Šala; Nejc Hodnik; Janez Kovač; Tiziano Montini; Michele Melchionna; Paolo Fornasiero

doi:10.1021/acs.chemmater.3c00125

Nanotubular TiO _x N _y -Supported Ir Single Atoms and Clusters as Thin-Film Electrocatalysts for Oxygen Evolution in Acid Media

Chem Mater. 2023 Mar 9;35(6):2612-2623. doi: 10.1021/acs.chemmater.3c00125. eCollection 2023 Mar 28.

Authors

Luka Suhadolnik¹, Marjan Bele², Miha Čekada³, Primož Jovanovič², Nik Maselj^{2

4}, Anja Lončar^{2

5}, Goran Dražić², Martin Šala⁶, Nejc Hodnik^{2

5

7}, Janez Kovač⁸, Tiziano Montini¹, Michele Melchionna¹, Paolo Fornasiero¹

Affiliations

¹ Department of Chemical and Pharmaceutical Sciences, CNR-ICCOM Trieste and INSTM Trieste Research Units, University of Trieste, via L. Giorgieri 1, 34127 Trieste, Italy.
² Department of Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
³ Department of Thin Films and Surfaces, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
⁴ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.
⁵ University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia.
⁶ Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
⁷ Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia.
⁸ Department of Surface Engineering, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.

Abstract

A versatile approach to the production of cluster- and single atom-based thin-film electrode composites is presented. The developed TiO _x N _y -Ir catalyst was prepared from sputtered Ti-Ir alloy constituted of 0.8 ± 0.2 at % Ir in α-Ti solid solution. The Ti-Ir solid solution on the Ti metal foil substrate was anodically oxidized to form amorphous TiO₂-Ir and later subjected to heat treatment in air and in ammonia to prepare the final catalyst. Detailed morphological, structural, compositional, and electrochemical characterization revealed a nanoporous film with Ir single atoms and clusters that are present throughout the entire film thickness and concentrated at the Ti/TiO _x N _y -Ir interface as a result of the anodic oxidation mechanism. The developed TiO _x N _y -Ir catalyst exhibits very high oxygen evolution reaction activity in 0.1 M HClO₄, reaching 1460 A g^-1 _Ir at 1.6 V vs reference hydrogen electrode. The new preparation concept of single atom- and cluster-based thin-film catalysts has wide potential applications in electrocatalysis and beyond. In the present paper, a detailed description of the new and unique method and a high-performance thin film catalyst are provided along with directions for the future development of high-performance cluster and single-atom catalysts prepared from solid solutions.