In this study, we have synthesized nanostructured titanium dioxide (TiO₂) photocatalysts under different configurations, viz., anatase, rutile and anatase/rutile heterophase (E_g = 3.14–2.96 eV) through a sol–gel route. The photocatalytic performance of the heterophase samples was better than that of their phase-pure counterparts. Photocatalytic performance was maximum for sample T12H (50% rutile) with a rate constant, k = (7.38 ± 1.48) × 10⁻² min⁻¹. This is ca. 47% greater than that estimated via an extrapolation method using the values for phase pure samples indicating synergistic effects. High-resolution transmission electron microscope (HRTEM) analysis and the phase-dependent broadening of core-level X-ray photoelectron spectroscopy (XPS) analysis indicate the formation of well-defined anatase/rutile interfaces. Interfacial charge transfer is the critical factor for this synergistic effect. To analyze the charge transfer pathways, the possible band alignment scheme was analyzed through the precise determination of band alignments from XPS, employing the Ti 2p_3/2 core level as a reference. We found a staggered rutile band alignment with the valence band edge of rutile lying above that of anatase, indicating the transfer of photogenerated free electrons from the conduction band of rutile to that of anatase and hole transfer from the valence band of anatase to rutile. These inferences are validated through Mott–Schottky analysis as well.

中文翻译：

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溶胶-凝胶衍生的锐钛矿/金红石异相 TiO2 中的能带排列和界面电荷转移：解释协同光催化活性

在这项研究中，我们合成了不同构型的纳米结构二氧化钛（TiO ₂）光催化剂，即。、锐钛矿、金红石和锐钛矿/金红石异相（E _g = 3.14–2.96 eV）通过溶胶-凝胶途径。多相样品的光催化性能优于纯相样品。样品T12H（50%金红石）的光催化性能最大，速率常数k = (7.38 ± 1.48) × 10 ^-2 min ^-1。这是大约。比使用纯相样品值通过外推法估计的值高出 47%，表明具有协同效应。高分辨率透射电子显微镜 (HRTEM) 分析和核心级 X 射线光电子能谱 (XPS) 分析的相位依赖性展宽表明明确的锐钛矿/金红石界面的形成。界面电荷转移是这种协同效应的关键因素。为了分析电荷转移路径，使用 Ti 2p _3/2核心能级作为参考，通过 XPS 精确确定能带排列来分析可能的能带排列方案。我们发现了交错的金红石带排列，金红石的价带边缘位于锐钛矿的价带边缘之上，这表明光生自由电子从金红石的导带转移到锐钛矿的导带，并且空穴从锐钛矿的价带转移到金红石。这些推论也通过莫特-肖特基分析得到验证。