Action spectra of P25 TiO2 and a visible light absorbing, carbon-modified titania in the photocatalytic degradation of stearic acid
Action spectra of P25 TiO2 and a visible light absorbing, carbon-modified titania in the photocatalytic degradation of stearic acid
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DOI：
10.1016/j.apcatb.2013.12.008
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发表时间：
2014-05-05
影响因子：
22.1
通讯作者：
O'Rourke, Christopher
中科院分区：
文献类型：
--
作者：
Quesada-Cabrera, Raul;Mills, Andrew;O'Rourke, Christopher
报道了Evonik（前身为Degussa）P25 TiO 2和碳改性TiO 2 Kronos VLP 7000样品薄膜的光子效率随激发波长（300-430 nm; FWHM类似于7.5 nm）的变化，即硬脂酸降解的作用光谱，硬脂酸是固体表面有机污染物光催化破坏的模型有机物。对于这些半导体光催化剂中的每一个，在365 nm（FWHM = 18 nm），硬脂酸的降解速率的依赖性，在辐照度，I，被确定和速率被发现是成比例的I-0.65和I-0.82的P25和Kronos二氧化钛，分别。假设这种关系在所有波长下都成立，则通过绘图来修改两种不同半导体光催化剂的作用光谱，（R-SA（硬脂酸破坏率，单位：分子cm（-2）s（-1））/I-θ）与激发波长（lambda（excit）），两者都与原始的明显不同。（未修改的）作用光谱，其是（R-SA/I =光子效率，xi）对λ（激发）的曲线图。P25 TiO 2的修改后的作用光谱的形状与其他有机矿化反应的报告一致，并与P25 TiO 2的漫反射数据（Kubelka-Munk图）相关，尽管有一些证据表明，在硬脂酸的光降解中，活性相是P25中存在的α-形式。米色Kronos VLP 7000 TiO 2化合物的未改性和改性作用光谱在可见光下表现出很小或没有活性，即（λ（激发）>400 nm）和在350 nm处的峰。Kronos粉末含有一种黄色/棕色共轭、可提取的有机敏化剂，已被其他人确定为负责其报告的光催化可见光活性的物质。但是，在空气中，使用UVA或可见光照射具有和不具有硬脂酸涂层的Kronos粉末膜，会迅速漂白（350 nm）。提出Kronos和P25粉末薄膜在波长上的差异
The photonic efficiencies of films of Evonik (formerly Degussa) P25 TiO2 and carbon-modified TiO2 Kronos VLP 7000 samples are reported as a function of excitation wavelength (300-430 nm; FWHM similar to 7.5 nm), i.e. the action spectra, for the degradation of stearic acid, a model organic for the photocatalytic destruction of solid surface organic pollutants. For each of these semiconductor photocatalysts, at 365 nm (FWHM = 18 nm), the dependence of the rate of degradation of stearic acid, upon the irradiance, I, is determined and the rate is found to be proportional to I-0.65 and I-0.82 for P25 and Kronos titania, respectively. Assuming this relationship holds at all wavelengths, the action spectra for two different semiconductor photocatalysts is modified by plotting, (R-SA (rate of stearic acid destruction, units: molecules cm(-2) s(-1))/I-theta) vs. wavelength of excitation (lambda(excit)), and both differ noticeably from those of the original (unmodified) action spectra, which are plots of (R-SA/I = photonic efficiency, xi) vs. lambda(excit). The shape of the modified action spectrum for P25 TiO2 is consistent with that reported by others for other organic mineralisation reactions and correlates well with diffuse reflectance data for P25 TiO2 (Kubelka-Munk plot), although there is some evidence that the active phase, in the photodegradation of stearic acid, is the anatase form present in P25. The unmodified and modified action spectra of the beige Kronos VLP 7000 TiO2 compound exhibits little or no activity in the visible i.e. (lambda(excit) >400 nm) and a peak at 350 nm. The Kronos powder contains a yellow/brown conjugated, extractable, organic sensitiser which has been identified by others as the species responsible for its reported photocatalytic visible light activity. But, irradiation of the Kronos powder film, with and without a stearic acid coating, in air, using UVA or visible light, bleaches rapidly (350 nm. It is proposed that the difference between the Kronos and P25 powder films at wavelengths