Operando Investigation of Heterogeneous Photocatalysis by Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

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Photocatalytic reactions use only sunlight as energy source and are therefore valuable elements in our current economic transition away from fossil fuels. For realistic insights into the ongoing process, photocatalytic transformations should ideally be studied in real time. While MAS NMR spectroscopy is a powerful tool for investigating interfaces and catalytic processes, the operando investigation of heterogeneous photocatalysis is still a great challenge. The goal of this project is the development of light irradiation solid-state NMR spectroscopy under Magic Angle Spinning for the in situ and operando investigation of model photocatalytic reactions over titania. A custom-built MAS NMR probe will allow to irradiate a sample slurry inside a transparent rotor with light of variable wavelengths and intensity. The potential of this methodology will first be demonstrated on the photocatalytic oxidation of small alcohols. Combination of operando techniques with advanced NMR techniques will yield new insights into the structure of the catalyst surface and its interface with the liquid, into reaction mechanisms and deactivation processes. In the last part of the project, we will implement the operando MAS NMR investigation of the photocatalytic reduction of carbon dioxide.