Heterogeneous Oxidation Catalysis in the Liquid Phase

C01: Synthesis of Transition Metal Oxides with Controlled Mesostructure

Prof. Dr. Malte Behrens • PD Dr. Harun Tüysüz

The project aim is the development of pristine mesostructured cobalt oxide with tunable morphology as well as preparation of iron, vanadium and manganese incorporated in its crystal structure via hard templating and post-treatment processes. This synthesis concept is complemented by the crystalline precursor decomposition approach, which focuses on precursor deposition on surfaces to make well-defined powder layers accessible for surface science studies. The project builds upon the results of the first funding period, where the effects of morphology and iron doping/substitution have been successfully established. Vanadium and manganese have ability to adopt multiple high oxidation states and their combination with cobalt oxide is expected to tune its crystal, electronic and band structures among other physicochemical properties. The influence of this kind of alteration will be investigated for liquid phase catalytic transformation reactions by focusing on oxygen evolution half reaction of water electrolysis on the one hand, and on aerobic 2-propanol oxidation on the other hand. The electrocatalysts alteration will be monitored under working condition by coupling Raman Microscopy with Inductively Coupled Plasma Optical Emission Spectrometry (ICP-​OES). The thermal catalysis tests will be conducted in the presence of steam to study the effect of solvents.

This study will allow gaining insights about phase transformation and compositional change of electrocatalysts and thermal catalysts, their activation or deactivation as well as determination of active centers. This synthesis project will play a central role within the consortium; the prepared and well-characterized selected samples will be delivered to partners in Areas A and B for in-deep structural analyses and catalytic investigations. At the same time, the successful materials basis of the first funding period, e.g., the Co-Fe systems, will remain accessible for in-depths studies.

(Figure: Scheme for the co-precipitation synthesis of unique mesostructures. The platelet morphology of the layered precursor is maintained during mild calcination and porous oxide platelets shown on the right crystallize in a topotactic manner with crystalline ordering over the whole platelets).