Joint Effects of Photoactive TiO2 and Fluoride-Doping on SnO2 Inverse Opal Nanoarchitecture for Solar Water Splitting

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• 作者：Yun Gun ; Gwang Yeom Song ; Vu Hong Vinh Quy ; Jaeyeong Heo ; Hyunjung Lee ; Kwang-Soon Ahn ; Soon Hyung Kang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 16, 2015
• 年：2015
• 卷：7
• 期：36
• 页码：20292-20303
• 全文大小：740K
• ISSN：1944-8252

文摘

Inverse opal (IO) films of tin dioxide (SnO<sub>2sub>) were fabricated on polystyrene (PS) beads (diameter = 350 nm (卤20 nm) with a spin coating method. To compensate for the large band gap (E<sub>gsub> = 3.8 eV), a thin TiO<sub>2sub> shell was deposited on the SnO<sub>2sub>鈥揑O films with atomic layer deposition (ALD), which produced shells with thicknesses of 10鈥?0 nm. The morphological changes and crystalline properties of the SnO<sub>2sub> and TiO<sub>2sub>-coated SnO<sub>2sub> (herein after referred to as TiO<sub>2sub>/SnO<sub>2sub>) IO films were investigated with field-emission scanning electron microscopy and X-ray diffraction, respectively. The photoelectrochemical (PEC) behavior of the samples was tested in a 0.1 M KOH solution under 1 sun illumination (100 mW/cm<sup>2sup> with an AM 1.5 filter). The highest PEC performance was obtained with the TiO<sub>2sub>(10 nm)/SnO<sub>2sub> IO films, which produced a photocurrent density (J<sub>scsub>) of 4.67 mA/cm<sup>2sup> at 0.5 V (vs NHE) and was sequentially followed by the TiO<sub>2sub>(20 nm)/SnO<sub>2sub>鈥揑O, TiO<sub>2sub>(30 nm)/SnO<sub>2sub>鈥揑O, TiO<sub>2sub> (40 nm)/SnO<sub>2sub>鈥揑O and SnO<sub>2sub> IO films. Overall, the thin TiO<sub>2sub> shell covered on the SnO<sub>2sub>鈥揑O core enhanced J<sub>scsub> by 3 orders of magnitude, which in turn the PEC activity. This is mainly ascribed to the extremely low charge-transfer resistance (R<sub>ctsub>) in the photoelectrode/electrolyte and at the TiO<sub>2sub>/SnO<sub>2sub> interface, as well as the contribution of the photoactive TiO<sub>2sub> layer, which has an E<sub>gsub> of 3.2 eV. Moreover, to improve the electrical conductivity of the core SnO<sub>2sub> IO film, the films were doped with 10 mol % of F. The F<sup>鈭?/sup> doped films were labeled as the FTO IO film. The R<sub>ctsub> of the FTO-IO films decreased because of the improved electronic conductivity, enhancing the PEC performance of the TiO<sub>2sub>(10 nm)/FTO-IO films by approximately 20%. The core鈥搒hell nanowire mesh nanoarchitecture is therefore suggested to provide an insight for designing the peculiar structure based on the material鈥檚 properties and the engineering of their band gap energy for highly efficient PEC performance.