Synthesis and Characterization of the Optical Properties of Pt-TiO₂Nanotubes

Abstract

Composite Pt-doped TiO 2 nanotubes (Pt-TNTs) were synthesized via alkaline fusion-hydrothermal method (AFHM) under ambient atmosphere pressure. Further systematic characterization of Pt-TNTs was performed by using XPS, surface photovoltage spectroscopy (SPS), electric field-induced surface photovoltage spectroscopy (FISPS), UV-Vis diffuse reflectance spectrophotometry (UV-Vis), TEM, and XRD. XPS spectrum showed double peaks which accounted for the presence of platinum dioxide and platinum oxide (PtO 2 and PtO, PtO + ). Composition analysis showed that the particulate matters on surface of Pt-TNTs were composed of PtO + and TiO 2 . The results of SPS and FISPS demonstrated that the bound exciton showed sub-band gap transition characteristics with the asymmetric changes of photoelectric property corresponding to changes in polarity and strength of the external electric field. Furthermore, the influence of the changed microstructure morphology of Pt-doped TNTs on both the photovoltage spectroscopy and the lifetime of photogenerated carriers which occurred at the interfaces of Pt-TNTs was observed. Result of XRD indicated that a mixture of anatase and rutile phases prevailed in Pt-TNTs. Contact potential barriers consisting of PtO + , anatase, rutile, and PtO + are presumed to form upon PtO + particle that deposited on the surface of Pt-TNTs.

Deposition of Pt nanoparticles on TiO2 by pulsed direct current magnetron sputtering for selective hydrogenation of vanillin to vanillyl alcohol

“…According to literature, the typical binding energies of Pt in the form of Pt metal, PtO, and PtO2 species appears at ca. 71, 72.4, 74.9 eV, respectively [28][29][30][31][32]. Considering the Pt/TiO2 prepared by PDC-MSD, the shift in XPS peaks due to Pt metal towards lower binding energy, as compared to the value reported in the references, could be attributed to several factors.…”

Reaction mechanism and pathway for the selective photocatalytic hydrogenation of nitroaromatics over TiO2 in alcohols

“…Moreover, the XRD peaks at 2θ equal to 25.3º, 37.8, 48.1º, 54.0º, 55.0º, 68.9º, 70.2º, and 75.3º were assigned to anatase phase. Meanwhile, the XRD peaks at 27.4º, 36.1º, 41.2º, 56.5º, and 62.7º were assigned to rutile phase [24,31,39,40]. Pt/P25 catalyst exhibited the same characteristic peaks of the anatase and rutile phase as pure P25-TiO 2 , indicating that the catalyst maintained the crystallite structure after deposition of Pt.…”

“…The UV-Vis absorption spectra were used to investigate the light absorption of pure P25-TiO 2 and prepared Pt/P25 catalysts and the results were shown in Figure 12. The absorption band of P25-TiO 2 was found at 392 nm, which could be ascribed to the light absorption caused by the excitation of electron transfer from the valence band to the conduction band [21,24,44,45]. Pt/P25 catalyst exhibited two kinds of characteristic light absorption edges in the UV-Vis spectra, including the sharp absorption band in the UV region (wavelength < 400 nm), which was attributed to the band structure of the original P25-TiO 2 , and the absorption band in the visible spectra (wavelength of 400 -800 nm), due to the Pt nanoparticles doping [8,45,46].…”

“…In the several reports, Pt/TiO 2 catalysts contribute to improving the activity and selectivity and activity by etrapping with consequent enhancement of the charge separation to preventing the fast recombination of eand h + pairs. Also, Ptbased TiO 2 catalyst is known to be effective for Ar-NO 2 hydrogenation to Ar-NH 2 because Pt selective to hydrogenate the N=O bond [15,16,[18][19][20][21][22][23][24]. Besides, Pt metal has received attention due to its excellent reactivity and selectivity, low cost, high stability, and easy to access [20][21][22].…”