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DS: Fachverband Dünne Schichten

DS 16: Focus Session: 2D Transition Metal Carbides, Nitrides and Carbonitrides III (joint session DS/MM/O)

DS 16.1: Hauptvortrag

Donnerstag, 21. März 2024, 15:00–15:30, A 053

Heterogeneous catalysis with MXenes: the role of the surface passivating groups and the structural defects — •Alexey Fedorov — Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland

Mo2CTx, two-dimensional (2D) molybdenum carbide of the MXene family (Tx are passivating surface groups), contains only surface Mo sites and is therefore a convenient model catalyst for structure-activity studies. For instance, the catalytic activity of Mo2CTx in Fischer-Tropsch (FT) synthesis increases when a Tx coverage is minimized, the latter achieved via reductive defunctionalization of Tx groups under H2. However, high temperature H2 treatment of Mo2CTx removes also ca. one third of the carbidic lattice carbon, yielding a 2D-Mo2C1-x material that is an active methanation catalyst. The removal of Tx species is also possible in the FT conditions (i.e., in the presence of CO), and this gives 2D-Mo2C without detectable carbon vacancies and Tx groups. 2D-Mo2C material, in contrast to 2D-Mo2C1-x, converts CO to diesel range alkanes. Other examples considered include dry reforming of methane, (reverse) water gas shift as well as electrocatalytic reactions (HER, NO3RR) of Mo2CTx:M, i.e., a material with dopant sites (M = Co, Fe) replacing Mo sites in the lattice of Mo2CTx.

Keywords: MXenes; Heterogeneous catalysis; Reductive defunctionalization; Structure-activity studies; Dopant and vacancy sites