c/o Dipartimento di Scienze Chimiche, Farmaceutiche ed Agrarie, ISOF CNR, UoS di Ferrara, Università di Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy.
Dipartimento di Scienze Chimiche, Farmaceutiche ed Agrarie, Università di Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy.
Photochem Photobiol Sci. 2021 Dec;20(12):1635-1644. doi: 10.1007/s43630-021-00137-4. Epub 2021 Nov 21.
Visible light (λ > 420 nm) selective photooxidation of phenylmethanol and 4-pyridinylmethanol in CHCN to the corresponding aldehydes on N-TiO is compared with homemade undoped TiO (U-TiO) and commercial undoped anatase specimens (such as PC105, PC500). Significant differences observed between N-TiO and undoped TiO are neither directly related to the surface area nor to the adsorbed amount of alcohol in the dark by surface area unit. FTIR and EPR spectroscopies are used to study the surface of TiO samples and to deeply understand the phenomena intervening in the visible-light photocatalytic activation of the doped vs the undoped oxides. In particular, it is shown that on N-TiO (and also on undoped PC105) strong Lewis acid sites (LAS) exist. The favorable role of LAS on the photocatalytic activity is illustrated by the higher photooxidation of 4-pyridinylmethanol vs phenylmethanol over N-TiO and PC105 in contrast to the other undoped samples, whose visible light sensitivity originates from a charge transfer between the alcohol and the solid. EPR spectra of N-TiO point out the presence of paramagnetic centers related to nitrogen that disappear when the photocatalyst is irradiated with visible light in the presence of alcohol, which starts its oxidative process. On the basis of presented results, we propose that doping with N introduces new intraband gap states that not only contribute to LAS and adsorption of alcohol but also are directly involved in the photochemical process occurring under visible light irradiation.
可见光（λ > 420nm）选择性光氧化苯甲醇和 4-吡啶甲醇在 CHCN 中的醛在 N-TiO 上的光氧化与国产未掺杂 TiO（U-TiO）和商业未掺杂锐钛矿样品（如 PC105、PC500）进行了比较。在 N-TiO 和未掺杂 TiO 之间观察到的显著差异既与表面积无关，也与单位表面积上黑暗中吸附的醇量无关。傅里叶变换红外光谱和电子顺磁共振光谱用于研究 TiO 样品的表面，以深入了解掺杂与未掺杂氧化物在可见光光催化激活过程中干预的现象。特别是，它表明在 N-TiO（以及未掺杂的 PC105）上存在强路易斯酸位（LAS）。通过 N-TiO 和 PC105 对 4-吡啶甲醇的光氧化率高于苯甲醇，与其他未掺杂样品形成对比，证明了 LAS 在光催化活性中的有利作用，而其他未掺杂样品的可见光灵敏度源于醇与固体之间的电荷转移。N-TiO 的 EPR 光谱指出存在与氮有关的顺磁中心，当光催化剂在存在醇的情况下用可见光照射时，这些中心会消失，这表明光催化氧化过程开始。基于呈现的结果，我们提出用 N 掺杂引入新的带内间隙态，这些间隙态不仅有助于 LAS 和醇的吸附，而且直接参与可见光照射下发生的光化学过程。
