Anatase TiO2 single crystals with a large percentage of reactive facets.
Owing to their scientific and technological importance, inorganic single crystals with highly reactive surfaces have long been studied. Unfortunately, surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. A typical example is titanium dioxide (TiO2), which has promising energy and environmental applications. Most available anatase TiO(2) crystals are dominated by the thermodynamically stable {101} facets (more than 94 per cent, according to the Wulff construction), rather than the much more reactive {001} facets. Here we demonstrate that for fluorine-terminated surfaces this relative stability is reversed: {001} is energetically preferable to {101}. We explored this effect systematically for a range of non-metallic adsorbate atoms by first-principle quantum chemical calculations. On the basis of theoretical predictions, we have synthesized uniform anatase TiO(2) single crystals with a high percentage (47 per cent) of {001} facets using hydrofluoric acid as a morphology controlling agent. Moreover, the fluorated surface of anatase single crystals can easily be cleaned using heat treatment to render a fluorine-free surface without altering the crystal structure and morphology.
ARC Centre of Excellence for Functional Nanomaterials, School of Engineering and Australian Institute for Bioengineering and Nanotechnology, Queensland 4072, Australia.
Hua Gui
HG
Yang
Cheng Hua
CH
Sun
Shi Zhang
SZ
Qiao
Jin
J
Zou
Gang
G
Liu
Sean Campbell
SC
Smith
Hui Ming
HM
Cheng
Gao Qing
GQ
Lu
D003460:Crystallization; D006358:Hot Temperature; D006858:Hydrofluoric Acid / Q000737:chemistry; D008854:Microscopy, Electron; D011789:Quantum Theory; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
C009495:titanium dioxide; D014025:Titanium; D006858:Hydrofluoric Acid