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O: Fachverband Oberflächenphysik

O 88: Poster Session VII: Oxides and insulators: Adsorption and reaction of small molecules I

O 88.8: Poster

Thursday, March 4, 2021, 10:30–12:30, P

Interaction of formic acid with magnetite surfaces – the DFT perspective — •Kai Sellschopp¹, Marcus Creutzburg^2,3, Björn Arndt^2,3, Heshmat Noei², Andreas Stierle^2,3, Stefan Müller¹, and Gregor Vonbun-Feldbauer¹ — ¹Institute of Advanced Ceramics, Hamburg University of Technology — ²DESY NanoLab, Deutsches Elektronen-Synchrotron, Hamburg — ³Fachbereich Physik, Universität Hamburg

Formic acid (HCOOH) molecules are present in atmospheric conditions and furthermore, can be seen as the smallest representative of the carboxylic acid family. Magnetite (Fe₃O₄) nanoparticles are utilized in various applications, such as waste water treatment, single-atom catalysis or hybrid materials. Therefore, studying the interaction of formic acid with the major facets of magnetite nanoparticles, namely the {111} and {001} facets, is highly interesting for improving their performance. Here, we present results on the adsorption of formic acid on both magnetite (111) and (001) studied through Density Functional Theory (DFT) calculations. In agreement with surface science experiments, the formation of a (√3×√3)R30^∘ superstructure and two different binding modes, a quasi-bidentate and a chelating mode, are found on the (111) surface, and the observed restructuring of the (001) surface is explained. In all studied cases, the dissociation of formic acid into formate and hydrogen is energetically favourable. Calculated surface phase diagrams give further insights in the processes involved under experimental conditions and indicate a stabilisation of iron vacancies on the (111) surface upon formic acid dissociation.