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IBEC Seminar: Stijn Mertens
Wednesday, February 8, 2017 @ 12:00 pm–1:00 pm
Electrochemical surface science of TiO2 rutile (110), graphene and boron nitride
Stijn Mertens, TU Wien, Institute of Applied Physics / KU Leuven, Chemistry DepartmentThe rational design of catalysts and other functional materials requires an atomic-level understanding of their structure and of the interface to supporting surfaces. I will present an in situ electrochemical STM study of TiO2 rutile (110) with atomic resolution. This is achieved using a new wet-chemical cleaning procedure for the substrate and with Pt-Ir tips. If tungsten tips are used, WO3 is spontaneously formed at the tungsten–liquid interface and strongly adsorbs on oxide surfaces below their point of zero charge through an electrostatic mechanism. Under clean conditions, the TiO2 rutile (110) surface shows a bulk-like, unreconstructed structure, which resembles its appearance in vacuum, even though the surface is probably fully hydroxylated.
In the second part of my talk, I will focus on 2D materials graphene and hexagonal boron nitride. By combining electrochemical grafting of diazonium salts with tip-induced nanolithography, nanopatterned sp3 defects can be introduced, opening perspectives towards graphene band gap engineering [1,2]. Hexagonal boron nitride, isoelectronic with graphene, can be grown on Rh(111) and forms a so-called nanomesh superstructure [3], characterized by a 3.2-nm lattice constant and strong electronic corrugation, useful for trapping atoms and molecules. Electrochemical intercalation of hydrogen between the boron nitride layer and the rhodium substrate leads to microscopic flattening within the 2-dimensional material and a macroscopic 10% change in adsorption energy [4].
[1] Greenwood et al., ACS Nano 9, 2015, 5520.
[2] Huynh et al., Nanoscale 9, 2017, 362.
[3] Corso et al., Science 303, 2004, 217.
[4] Mertens et al., Nature 534, 2016, 676.
