Direct observation of tunable surface structure and reactivity in TiO2 nanopowders

•We use nuclear reaction analysis to study oxygen and deuterium content in titania nanopowders.•DFT calculations display the electronic structure impact of surface oxygen depletion.•Isotope and thermal studies distinguish oxide content from adsorbed species.•Reactivity with hydrogen (deuterium) displays distinct behavior characteristic of metallic surfaces.•Laser evaporation synthesis creates oxygen depletion at metal oxide nanopowder surfaces. Surface structure and reactivity is of primary importance in numerous metal oxide applications. Nanopowders can offer advantages both in ease of preparation and in total surface area relative to monocrystals. Although monocrystal surfaces have been characterized using a variety of spectroscopy and microscopy techniques, key features of these surfaces may not translate to nanopowders. In previous studies of alumina and zirconia, we employed nuclear reaction analysis coupled with density functional calculations to show that the atomic and electronic structures of these nanopowder surfaces are distinct from those predicted thermodynamically for macroscopic crystals. Here, we report similar findings for the technologically important metal oxide TiO2. For the first time, we extend our studies to characterize these nanopowders’ surface reactivity with oxygen and hydrogen. We observe reactivity indicative of surface states with metallic character distinct from the stoichiometric oxide. This notable behavior holds crucial implications for use of these powders as catalysts and catalyst supports. [Display omitted]