From Iron, over Nickel to Zinc: X-Ray Absorption Spectroscopy on 1st Row Transition Metals

by Steffen Schlichter (Paderborn University) , Sven Wendtholt (Paderborn University)




Part 1: CO2 Methanation on Decomposed Ni-Metal Organic Frameworks (MOFs)
Part 2: CO Oxidation on Iron Oxide Catalysts
Part 3: Plasma Treatment of Zinc Oxide Nanostructures

Sven Wendholt & Steffen Schlicher
AK Prof. Matthias Bauer
Paderborn University

Long-term storage of energy from renewable resources is crucial in future sustainable power supply. Ni nanoparticles gained by decomposition and following activation of Ni-based MOFs can act as promising catalysts in CO2 methanation and thus for long-term storage of energy. To optimize the catalyst properties, the understanding of the decomposition processes is fundamental. Therefore, XAS investigations can be a useful tool for in depth knowledge of the precatalyst structure as well as the catalytic active species.

Besides search for new energy sources, emission reduction has never been more important and yet challenging. Large amounts of toxic carbon monoxide are emitted into the atmosphere, mostly by traffic. Usually noble metals such as platinum, palladium or rhodium are utilized in so called three-way-catalysts in which CO is oxidized to non-toxic CO2 but besides their controversially discussed effects on the ecosystem they are without any doubt very expensive. Iron oxides present a potent alternative but to get to the high activity of noble metals we have to understand the mechanisms behind CO oxidation on iron oxides and especially behind the formation of catalytically active species or unwanted agglomerates during the preparation. In-situ XAS experiments during the annealing procedure are performed to shed light upon these processes.

Atmospheric pressure plasmas offer a broad range of potential applications in the treatment of various materials. Especially zinc oxide nanostructures have gained great attention due to their wide range of applications as functional materials. Their electronic properties depend on their defect structure and density which can be altered by plasma treatment. Unfortunately the mechanisms behind this are poorly understood or completely unknown. To contribute here we designed a special setup for atmospheric-pressure DBD plasma to investigate the plasma modifications on different zinc oxide nanostructures in-situ with X-ray absorption spectroscopy.