- Ruhr-Universität Bochum

The CRC/TRR 247 „Heterogeneous Oxidation Catalysis in the Liquid Phase – Mechanisms and Materials in Thermal, Electro-, and Photocatalysis” started in 2018 and is currently applying for its second funding period. The first funding period is devoted to the establishment of experimental structure–activity correlations and theoretical modelling of the active site candidates. In the second funding period, we will converge theory and experiment and address the reaction mechanisms. Additionally, we will start to generalize the results to other oxide catalysts. The CRC/TRR 247 includes 21 projects, which are divided into four categories.

The investigated catalysts are cobalt oxides promoted with other metal ions such as iron, which are applied as nanoparticles (NPs) in suspensions or deposited on electrodes. The focus is on spinels (Co₃O₄, CoFe₂O₄) and perovskites (LaCoO₃, LaFeO₃), which allow systematic substitution studies (Co_3-xFe_xO₄, La_1-xSr_xCo_1-xFeO₃). Sophisticated synthesis methods in area C such as spray flame synthesis or colloid-based methods are applied to obtain phase-pure uniform nanoparticles with narrow size distribution. By using liquid-phase based methods also, the NP morphology can be controlled. The overarching aim is to establish structure-activity correlations, which are strongly influenced by the defect structure characterized in area B. For example, oxygen vacancies play a major role in the thermal oxidation of alcohols, and the oxygen evolution reaction (OER) catalyzed by the cobalt oxide NPs involves additional structural changes including the formation of hydroxides. It is the task of the projects in area A to determine the catalytic properties of the various samples. A matrix consisting of reactants to be oxidized and of oxidizing agents has been established as basis of a comprehensive comparative study.