Friday, 23 Julyl 10:00

The title of this webinar is: “The surface chemistry of colloidal nanocrystals”

ABSTRACT

Colloidal nanocrystals are hybrid objects in which the properties of core and surface both determine the characteristics of the entire nanocrystal. The surface is often capped by (in)organic ligands which determine colloidal stability and the physical and chemical properties. As a result, nanocrystal surface chemistry, i.e., the understanding of and control over the ligand shell, has become one of the central themes in nanocrystal research.

The study of organic ligands through solution NMR spectroscopy;  first, the various NMR tools which provide information specific to nanocrystal surfaces are introduced. We will discuss the origin of the NMR line broadening of nanocrystal-bound ligands. Next we go over several general issues with solvents that are commonly used in nanocrystal synthesis at high temperatures (> 240 °C). In particular, 1-octadecene (ODE) and trioctylphosphine oxide (TOPO) are popular solvents but they tend to polymerize or decompose, respectively. The formed impurities are hard to remove from the nanocrystal product. I will show how surface chemistry can be used to enable nanoribbon memristors and photon upconversion. This truly means we have access to a surface chemistry on-demand.

As such, we establish surface chemistry as a key enabler in a variety of applications and NMR as the method of choice for characterizing the surface. This is a versatile field, with fundamental chemistry and spectroscopy leading to exiting innovations in physics and engineering and finally solving real-life problems.

ABOUT THE PRESENTER

Jonathan De Roo was born in 1989 in Belgium. He studied chemistry at Ghent University and obtained his PhD on the surface chemistry of metal oxide nanocrystals in 2016 under supervision of Prof. Isabel Van Driessche, Prof. Zeger Hens and Prof. José Martins. During his PhD, he conducted a three-month research stay in the lab of Prof. Maksym Kovalenko to study the surface of CsPbBr3 nanocrystals. He was a postdoctoral researcher at Columbia University (USA) for 2 years, working on crystallization mechanisms and custom-made ligands under supervision of Prof. Jonathan Owen. Before assuming his position at the University of Basel as assistant professor in September 2019, he spent one more year as post-doctoral researcher at Ghent University.