Tailored TiO₂(110) surfaces and their reactivity

Abstract

Electron bombardment from a filament as well as voltage pulses from a scanning tunnelling microscope tip have been employed to modify the surface of TiO2(110). Individual H atoms are selectively desorbed with electrical pulses of +3 V from the scanning tunnelling microscope tip, whilst leaving the oxygen vacancies intact. This allows us to distinguish between oxygen vacancies and hydroxyl groups, which have a similar appearance in scanning tunnelling microscopy images. This then allows the oxygen vacancy-promoted dissociation of water and O2 to be followed with the microscope. Electrical pulses between +5 and +10 V induce local TiO2(110)1 × 2 reconstructions centred around the pulse. As for electron bombardment of the surface, relatively low fluxes increase the density of oxygen vacancies whilst higher fluxes lead to the 1 × 2 and other 1 × n reconstructions.

The 2×1 reconstruction of the rutile TiO2(011) surface: A combined density functional theory, X-ray diffraction, and scanning tunneling microscopy study

“…STM measurements can give intricate details of surface processes [31,32]. However, a theoretical interpretation of atomically-resolved images is critical for such experiments, in particular in systems where electronic effects can offset geometrical height variations [33], and different species are only distinguished by small changes in image contrast [34][35][36]. At first sight, the comparison between simulated STM plots of the 'brookite (0 0 1)-like' model with previously-published STM data is not fully convincing.…”

A surface science perspective on TiO2 photocatalysis

“…Fundamental studies of the chemistry of water (and hydroxyls) on single crystal TiO 2 surfaces provide a starting point for understanding the photochemical properties of this process [853]. Extensive experimental [138,192,194,195,199,527,566,580,792,795,797,799,803,804,807,810,843,852,1681,1683,[1712][1713][1714][1715][1716][1717] and theoretical [193,522,527,792,810,824,826,830,831,1660,1682,1684,1711,1712,[1717][1718][1719] work has been invested in understanding the molecular-level interactions of water with single crystal TiO 2 surfaces. This author is unaware of any reports to date in which photochemical water splitting (in either half reaction) was performed on a single crystal TiO 2 surface under UHV conditions.…”

Understanding image contrast formation in TiO2with force spectroscopy

“…5,6 At variance with STM, atomic force microscopy with true atomic resolution [known as noncontact (nc)-AFM 7 ] has revealed a number of qualitatively different contrast modes. [8][9][10][11][12] Most images show either a contrast similar to STM with Ti 5c rows and defects imaged bright and O b rows imaged dark (protrusion mode), or its complete reversal (O b bright and Ti 5c rows and defects appearing dark), called hole mode. In a third but rather rare mode called neutral, OH groups and the O b atoms are imaged bright while O b vacancies and Ti 5c rows appear dark.…”