Synthesis and Characterization of the Optical Properties of Pt-TiO2Nanotubes (2017)

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,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">t</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi mathvariant="normal">δ</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>). Composition analysis showed that the particulate matters on surface of Pt-TNTs were composed of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">t</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi mathvariant="normal">δ</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>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<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">t</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi mathvariant="normal">δ</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>, anatase, rutile, and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">t</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi mathvariant="normal">δ</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>are presumed to form upon<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">t</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi mathvariant="normal">δ</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>particle that deposited on the surface of Pt-TNTs.