Atomic species identification at the (101) anatase surface by simultaneous scanning tunnelling and atomic force microscopy

Abstract

<div> Anatase is a pivotal material in devices for energy-harvesting applications and catalysis.</div> <div> Methods for the accurate characterization of this reducible oxide at the atomic scale are</div> <div> critical in the exploration of outstanding properties for technological developments. Here</div> <div> we combine atomic force microscopy (AFM) and scanning tunnelling microscopy (STM),</div> <div> supported by first-principles calculations, for the simultaneous imaging and unambiguous</div> <div> identification of atomic species at the (101) anatase surface. We demonstrate that dynamic</div> <div> AFM-STM operation allows atomic resolution imaging within the material&rsquo;s band gap. Based</div> <div> on key distinguishing features extracted from calculations and experiments, we identify</div> <div> candidates for the most common surface defects. Our results pave the way for the understanding</div> <div> of surface processes, like adsorption of metal dopants and photoactive molecules,</div> <div> that are fundamental for the catalytic and photovoltaic applications of anatase, and</div> <div> demonstrate the potential of dynamic AFM-STM for the characterization of wide band gap</div> <div> materials.</div>