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Apurba Sinhamahapatra1 Ha Young Lee1 Jong-Sung Yu1

1, Daegu Gyeongbuk Institute of Science and Technology, Daegu, , Korea (the Republic of)

Reduced or black TiO2-x materials were achieved by creating oxygen vacancies and/or defects at the surface using different methods. Fascinatingly, they exhibited an extended absorption in VIS and IR instead of only UV light with a band gap decreases from 3.2 (anatase) to ~1 eV. However, despite the dramatic enhancement of optical absorption of black TiO2-x material, it fails to show expected visible light-assisted water splitting efficiency [1,2]. Therefore, reduced or black TiO2 materials with optimized properties would be highly desired for efficient visible light photocatalysis.
In this presentation, we report H-doped reduced reduced of TiO2-x nanoparticles prepared by a controlled reduction via the simultaneous presence of two active reducing species, [Mg] and [H] in confined microenvironment at TiO2 surface for excellent photocatalytic H2 production from methanol-water system [3.4]. It exhibits outstanding activity (16 mmolg-1h-1) and excellent stability after Pt deposition for photochemical H2 generation from methanol-water in simulated sunlight. The excellent photoactivity of H:TiO2-x is attributed to the oxygen vacancies and H doping at TiO2 surface generated by [Mg] and [H]. The photocatalyst is working in the wavelength < 700 nm and exhibits reasonable visible-light activity with a quantum yield of 8.07, 3.92 and 2.02 % at 400, 420 and 454 nm, respectively along with the exceptionally high turnover number (122460) with respect to Pt. This outstanding activity can be correlated with the extended absorption in visible light, perfect band position, presence of an appropriate amount of Ti3+ and oxygen vacancy, and slower charge recombination.

References
X. Chen, L. Liu, P. Y. Yu, and S. S. Mao, Science, 2011, 331, 746-750
X. Chen, L. Liu, F. Huang, Chem. Soc. Rev., 2015. 44. 1861-19885.
A. Sinhamahapatra, J. P. Jeon, and J.-S. Yu, Energy Environ. Sci., 2015, 8, 3539-3444.
A. Sinhamahapatra, J. P. Jeon, J. Kang, B. Han and J.-S. Yu, Sci. Repts., 2016, 6, 27218.

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