Effective hydrogenation of TiO2 photocatalysts with CH3OH for enhanced water splitting: A computational and X-ray study

Tsai Te Wang, Putikam Raghunath, Yu Chang Lin, Yan Gu Lin*, Ming Chan Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

We have investigated computationally and experimentally the efficacy of CH3OH treatment of anatase TiO2 nanoparticles (NPs) and compared the results obtained with H2 as the hydrogenation source. The results indicate that TiO2 NPs heated at 300 °C in 120 Torr of CH3OH vapor is more effective than the samples heated under 800 Torr of H2 at the same temperature. Ultraviolet-visible spectroscopy (UV-VIS), Photoluminescence spectroscopy (PL) and X-ray diffraction spectroscopy (XRD) were employed to study the optical property. The effect of temperature of hydrogenation has been systematically studied for NPs in the 200–450 °C range for both H-sources based on H2 evolution, employing Xe lamp as the light source. The hydrogenated TiO2 NPs using H2 and CH3OH have been analyzed by soft X-ray absorption near-edge structure analyses with and without Xe lamp irradiation in situ. The result indicates that CH3OH hydrogenation can induce a much stronger Ti–O interaction along direction dz 2 and increase the unoccupied DOS of Ti t2g states. This is why the CH3OH treated TiO2 exhibits a greater photo-activity. The crucial role of the hydrogenation using CH3OH was also investigated systematically and confirmed by quantum-chemical calculations with complementary synchrotron-based X-ray techniques. The results are consistent with the predicted barriers for the formation of H atoms on the TiO2 surface, 4–9 kcal/mol, considerably lower than that in the H2 case, 48 kcal/mol.

Original languageEnglish
Pages (from-to)546-554
Number of pages9
JournalApplied Surface Science
Volume488
DOIs
StatePublished - 15 Sep 2019

Keywords

  • DFT calculation
  • Hydrogen evolution
  • Methanol treated titania
  • XANES spectra

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