Photoacoustic Fourier Transform Near- and Mid-Infrared Spectroscopy for Measurement of Energy Levels of Electron Trapping Sites in Titanium(IV) Oxide Photocatalyst Powders
Photoacoustic Fourier Transform Near- and Mid-Infrared Spectroscopy for Measurement of Energy Levels of Electron Trapping Sites in Titanium(IV) Oxide Photocatalyst Powders
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光声傅里叶变换近红外和中红外光谱测量氧化钛 (IV) 光催化剂粉末中电子捕获位点的能级
DOI：
10.1021/acs.jpcc.9b02876
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Murakami Naoya
中科院分区：
文献类型：
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作者：
Shinoda Tatsuki;Murakami Naoya
采用光声傅立叶变换近红外光谱（FT-NIR）和中红外光谱（FT-MIR）研究了TiO 2光催化剂粉末中的电子俘获位置。使用FT-NIR和FT-MIR的PA测量使得能够在导带底部以下的宽能级（0.1-1.9 eV）中原位观察电子捕获位点的能级。在紫外线（UV）照射，PA强度增加，这取决于波数，并在PA光谱的变化，观察到作为一个结果的三价钛物种所产生的电子在捕获网站的积累。此外，在紫外光照射过程中的PA光谱形状是本质上不同的晶体结构，它在很大程度上取决于晶体结构，而不是其他性能，如比表面积和粒径。不同样品的结果表明，金红石的电子陷阱能级比金红石和板钛矿浅，陷阱能级的深度顺序为板钛矿>金红石>金红石。因此，使用FT-NIR和FT-MIR的PA技术是测量半导体光催化剂中电子捕获位点能级的有效方法。
Electron trapping sites in titanium(IV) oxide photocatalyst powders were investigated by photoacoustic (PA) Fourier transform near-infrared spectroscopy (FT-NIR) and mid-infrared spectroscopy (FT-MIR). PA measurements using FT-NIR and FT-MIR enabled in situ observation of the energy levels of electron trapping sites in wide energy levels (0.1–1.9 eV) below the bottom of the conduction band. During ultraviolet (UV) irradiation, PA intensity increased depending on the wavenumber, and changes in the PA spectra were observed as a result of the trivalent titanium species generated by accumulation of electrons at trapping sites. Moreover, the PA spectral shape during UV irradiation was essentially different between the crystal structures, and it greatly depended on the crystal structure rather than other properties such as specific surface area and particle size. The results for various samples suggest that anatase has shallower energy levels of electron trapping sites than those of rutile and brookite, with the main energy level of the trapping sites being deep in the order of brookite > rutile > anatase. Thus, the PA technique using FT-NIR and FT-MIR is an effective method for measurements of energy levels of electron trapping sites in semiconductor photocatalysts.