Porphyrin layers at metal-electrolyte interfaces monitored by EC-STM and CV

Title : Porphyrin layers at metal-electrolyte interfaces monitored by EC-STM and CV

Abstract:

Porphyrin derivatives play a crutial role in biochemical processes like chlorophyll in the photosynthesis of plants, heme of red blood cells in the transport and storage of oxygen, and vitamin B-12 in the metabolism of creatures. Porphyrin derivatives are materials for electrocatalysts, drug production and cancer chemotherapy, sensors, solar cells, optoelectronic, data storage devices, and molecular electronics. We used electrochemical scanning tunneling microscopy (EC-STM) [1,2] and cyclic voltammetry (CV) to investigate these organic compounds at solid-liquid interfaces [3,4]. In particular the coadsorption of porphyrin molecules (TMPyP: Tetra(N-methyl-4-pyridyl)-porphyrin), sulfate and copper on Au(111), as well as iodine on Au(111), Au(110), and Au(100) was investigated with atomic resolution. With decreasing electrode potential the following sequence of phases was found: ( 3  7 )R19.1  SO 2 on Au(111)-(11), disordered SO42--layer on Au(111)-(11), ( 3  3)R30 coadsorption structure of 2/3 ML Cu and 1/3 ML SO 2-, 1 ML Cu covered by a layer of mobile SO 2-, a coadsorption layer of disordered porphyrin molecules and still mobile SO42-, overpotentially deposited Cu-multilayers terminated by the Moiré-type ( 3  7 )R19.1  SO 2 structure [5-8] and covered by a dense layer of flat lying TMPyP molecules showing a growing square and hexagonally ordered arrangement, and at even more negative potentials and low Cu concentrations in the solution a pseudomorphic Cu-monolayer covered by a ( 3  7 )R19.1  SO 2 layer and ordered porphyrin layer on top [9]. The formation of CuTMPyP-metalloporphyrins and the Cu-Au alloy at multilayer copper deposits is suggested. The growth of long-range ordered two dimensional porphyrin layer was found on iodine precovered Au(111) and Au(100) [10]. STM images reveal planar adsorption of molecules. High resolution images reflect ligands and empty molecular cores. Tunneling at different bias voltages enabled to reveal the orientation of porphyrins with respect to the crystalline electrode. [1] M. Nowicki, K. Wandelt, Scanning Probe Microscopy, in: Handbook of Solid State Chemistry, R. Dronskowski, S. Kikkawa, A. Stein (Eds), Wiley-VCH Verlag GmbH & Co., Vol. 3 (2017) 183-243, ISBN 978- 3-527-32587-0. [2] M. Nowicki, K. Wandelt, Electrochemical Scanning Tunneling Microscopy, in: K. Wandelt (Ed.), Encyclop. Interf. Chem.: Surf. Sci. Electrochem. , Vol. 1 (2018) 108-128, ISBN: 9780128097397. [3] M. Nowicki, K. Wandelt, Metal-Electrolyte Interfaces: An Atomic view, Surface and Interface Science. Interfacial Electrochemistry, Wiley-VCH Verlag GmbH, Weinheim, Vol. 8 (2020) 517, ISBN 978-3- 527- 41159-7. [4] M. Nowicki, K. Wandelt, (2018), Surfaces at metal-electrolyte interfaces in: Physics of Solid Surfaces, Eds. G. Chiarotti, P. Chiaradia, Landolt-Börnstein: Numerical Data and Functional Relationships in Science and Technology - New Series, Springer-Verlag GmbH Germany, Subvolume B, Series Vol. 45B (2018) p. 853, ISBN 978-3-662-53906-4. [5] B. Madry, K. Wandelt, M. Nowicki, Surf. Sci. 637-638 (2015) 77. [6] B. Madry, K. Wandelt, M. Nowicki, Electro. Acta 217 (2016) 249. [7] B. Madry, K. Wandelt, M. Nowicki, Appl. Surf. Sci. 388 (2016) 678. [8] B. Madry, K. Wandelt, M. Nowicki, in: K. Wandelt (Ed.) Encyclop. Interf. Chem.: Surf. Sci. Electrochem., 5 (2018) 281. [9] B. Madry, I. Morawski, T. Kosmala, K. Wandelt, M. Nowicki, Topics in Cat. 61 (2018) 1335. [10] T. Kosmala, R. Wasielewski, M. Nowicki, K. Wandelt, J. Phys. Chem. C 128 (2024) 1773. What will audience learn from your presentation? • Application of electrochemical scanning tunneling microscopy (EC-STM) and cyclic voltammetry (CV) in investigations of solid-liquid interfaces, • Potential induced assembly of organic and inorganic molecules on crystalline electrodes in solutions, • Determination of adsorption/desorption and/or oxidation/reduction processes at solid-liquid interfaces, • Identification of surface structures with atomic resolution, • Applications of porphyrins as two dimensional materials in future technology

Biography:

Prof. Dr. Marek Nowicki studied Physics at the University of Wroclaw, Poland and graduated as MS in 1992. He joined the group of Prof. S. Mroz at the Institute of Experimental Physics of the University of Wroclaw. He received his PhD in 1996 at the same institution. From 1998 till 2002 he worked as an Alexander von Humboldt Fellow and postdoc at Forschungszentrum Jülich GmbH, Germany (Prof. H.P. Bonzel). Then he joined the Department of Chemical Physics of the FHI-MPG in Berlin, Germany (prof. H.J. Freund). In 2006 he received habilitation and in 2016 professorship at the University of Wroclaw.