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O: Fachverband Oberflächenphysik
O 87: Focus Session: Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation III
O 87.8: Talk
Thursday, March 21, 2024, 17:00–17:15, HE 101
NC-AFM characterization of single-atom catalytic sites within metal-coordinated supramolecular networks — Bertram Schulze Lammers1, Nieves López-Salas2, Julya Stein Siena2, Hossein Mirhosseini3, Damla Yesilpinar1, Julian Heske3, Thomas D. Kühne3, Harald Fuchs1, Markus Antonietti2, and •Harry Mönig1 — 1Physikalisches Institut, Universität Münster — 2Max Planck Institute of Colloids and Interfaces, Potsdam — 3Theoretical Chemistry, Universität Paderborn
For the development of single atom catalysts, non-noble metal-organic layers combine functional variability with cost efficiency. Here we investigated reacted layers of melamine and melem on a Cu(111) surface by NC-AFM with CuOx-functionalized tips [1]. Upon deposition and subsequent heat treatments, the molecular units are completely deprotonated and adsorb flat and strongly chemisorbed. We observe a particularly extreme interaction of the deprotonated N- with single Cu atoms located at intermolecular sites. The NC-AFM measurements and ab-initio simulations indicate a pronounced interaction of O-species at these N-Cu-N sites. To study potential catalytic properties, we performed cyclic voltametry experiments on our samples at ambient pressure within a drop of electrolyte in a controlled O2 or N2 environment. Both Cu-nitride structures show a robust activity in irreversibly catalyzing the reduction of oxygen. The activity is assigned to the intermolecular N-Cu-N sites or corresponding oxygenated versions (N-CuO-N, N-CuO2-N) [2]. [1] H. Mönig, ChemComm 54, 9874 (2018); [2] B. Schulze Lammers et al., ACS Nano 16, 14284 (2022).
Keywords: Single atom catalysis; ORR; Cyclic voltametry; NC-AFM