Instability of hydrogenated TiO2.
J Phys Chem Lett
; 6(22): 4627-32, 2015 Nov 19.
Article
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| MEDLINE
| ID: mdl-26545303
ABSTRACT
Hydrogenated TiO2 (H-TiO2) is touted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using nuclear reaction analysis (NRA), Rutherford backscattering spectrometry, ultraviolet photoelectron spectroscopy, and X-ray photoelectron spectroscopy. Protons (40 keV) implanted at a â¼2 atom % level within a â¼120 nm wide profile of rutile TiO2(110) were situated â¼300 nm below the surface. NRA revealed that this H-profile broadened toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (â¼800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile at low temperatures, as well as its interfacial activity toward reduction, significantly limits the utilization of H-TiO2 as a photocatalyst.
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MEDLINE
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En
Revista:
J Phys Chem Lett
Año:
2015
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Article
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Estados Unidos