Niels Ostyn

KU Leuven (KUL), Belgium

Title: Controlled graphite functionalization by photocatalytic oxidation for rationally engineered electrocatalysis

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Biography

Niels Ostyn is doctoral researcher at KU Leuven in the Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT). He graduated at the University of Leuven in bioscience engineering with magna cum laude. His research expertise focuses on carbon materials, photocatalysis and materials characterization for the chemical functionalization and activation of graphene, graphite and carbon black. In the past, he performed an industrial internship at Total Research & Technology Feluy, where he worked on the improved preparation of graphene oxide for hydrotreating catalysts. He continued working on chemical modification of carbon materials in the research group of professor Johan Martens, studying the potential of heterogeneous photocatalysis. In the Martens group, he published three peer?reviewed articles in high-impact international scientific journals. Niels is also an active member of The Young European Catalysis Network (YEuCat), in which he works together with young motivated researchers on challenging scientific themes.

Abstract

Graphene, graphite and graphite oxide are extraordinary carbon materials with superb physical and chemical properties such as thermal and electrical conductivity. These carbons are often described as the wonder materials of the 21^st century. The number of high-end technological applications is expanding very rapidly. Liquid-phase chemical oxidation of graphite is the most prominent route towards oxidized graphite which has many interesting applications. These common wet chemical methods are however hazardous, produce lots of waste and do not allow handy control over the oxidation process and product. Efficient carbon?based electrocatalyst design requires in particular a mild and controllable graphite oxidation process to provide a chemically tailored surface with moderate oxidation degree. Therefore, there is a need for a more sustainable oxidation enabling better control over the reaction, with spatial and temporal control, for fine tuning of the oxidized graphite. In this respect, we propose a vapor phase photocatalytic process for oxygen functionalization of graphite, presenting these technological advantages. Graphite is photocatalytically oxidized at low temperature using a TiO₂ photocatalyst, UV light and a gas mixture consisting of molecular oxygen and water vapor.

Our work aims at the best electrocatalysts design for energy-efficient electrochemical synthesis under mild conditions. A series of different carbon-based catalysts are investigated, since carbon materials often suppress undesired competing reactions while favoring charge transport. The electrocatalysts are prepared through a two-step synthesis process, in which the carbon support is first oxygen functionalized, using remote TiO₂ photocatalysis, and further activated by heteroatom doping. This highly controllable process enables to tune multiple catalyst design parameters (conductivity, metal loading etc.), enhancing the material’s activity for electrochemical synthesis of valuable chemicals. To reveal all important material properties, the prepared catalyst is deeply looked into using advanced tools like electron microscopy and Raman and X-ray photoelectron spectroscopy.