Phase transition of individual anatase TiO 2 microcrystals with large percentage of (001) facets: a Raman mapping and SEM study
Phase transition of individual anatase TiO 2 microcrystals with large percentage of (001) facets: a Raman mapping and SEM study
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具有大比例 (001) 面的单个锐钛矿 TiO 2 微晶的相变：拉曼图谱和 SEM 研究
DOI：
10.1039/d2cp04882e
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发表时间：
2023
影响因子：
3.3
通讯作者：
Zhang, Zhenrong
中科院分区：
文献类型：
--
作者：
Lu, Weigang;Zhu, Hao;Birmingham, Blake;Craft, Nolan;Hu, Jonathan;Park, Kenneth;Zhang, Zhenrong
TiO 2已被广泛研究，在许多领域，包括电化学，光学等。了解锐钛矿-金红石相转变（ART）过程的机制是至关重要的，以TiO 2为基础的高活性光催化剂的设计和调整其性能的其他应用。在这项工作中，ART过程中，使用个别的纳米微粒与大百分比的（001）面进行了监测和研究。通过拉曼显微镜获得的相浓度演变与扫描电子显微镜（SEM）图像中观察到的形态演变相关。金红石微晶的ART主要由表面成核和生长控制，但单个金红石颗粒的ART过程是独特的，并取决于不同的金红石成核位点。观察到两种类型的转化途径。在一种类型的ART途径中，金红石相在微晶的角处成核，并首先沿晶体边缘在一个方向上沿着生长，随后在表面上的正交方向上在微晶的其余部分上传播并传播到晶体的本体。ART的动力学遵循具有两个不同速率常数的一级模型。快反应速率来自于表面成核和生长，慢反应速率来自于体相成核和生长。在另一种类型的ART途径中，多个金红石形核位点同时形成在微晶的不同边缘和角落上。金红石相从这些成核位点扩散到整个晶体上，具有小的体成核贡献。我们对单个微米级晶体ART的研究弥补了大块晶体和纳米级TiO 2颗粒之间的材料差距。金红石/金红石共存粒子为研究金红石和金红石在催化性能上的协同效应提供了一个很好的平台。
TiO2 has been extensively studied in many fields including photocatalysis, electrochemistry, optics, etc. Understanding the mechanism of the anatase–rutile phase transition (ART) process is critical for the design of TiO2-based high-activity photocatalysts and tuning its properties for other applications. In this work, the ART process using individual anatase micro-particles with a large percentage of (001) facets was monitored and studied. Phase concentration evolution obtained via Raman microscopy was correlated with the morphological evolution observed in scanning electron microscope (SEM) images. The ART of anatase microcrystals is dominated by surface nucleation and growth, but the ART processes of individual anatase particles are distinctive and depend on the various rutile nucleation sites. Two types of transformation pathways are observed. In one type of ART pathway, the rutile phase nucleated at a corner of an anatase microcrystal and grew in one direction along the edge of the crystal firstly followed by propagation over the rest of the microcrystal in the orthogonal direction on the surface and to the bulk of the crystal. The kinetics of the ART follows the first-order model with two distinct rate constants. The fast reaction rate is from the surface nucleation and growth, and the slow rate is from the bulk nucleation and growth. In the other type of ART pathway, multiple rutile nucleation sites formed simultaneously on different edges and corners of the microcrystal. The rutile phase spread over the whole crystal from these nucleation sites with a small contribution of bulk nucleation. Our study on the ART of individual micro-sized crystals bridges the material gap between bulk crystals and nano-sized TiO2 particles. The anatase/rutile co-existing particle will provide a perfect platform to study the synergistic effect between the anatase phase and the rutile phase in their catalytic performances.