Electronic Structure of 1D Lepidocrocite TiO2 as Revealed by Optical Absorption and Photoelectron Spectroscopy,The Journal of Physical Chemistry C

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Electronic Structure of 1D Lepidocrocite TiO2 as Revealed by Optical Absorption and Photoelectron Spectroscopy
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-04-05 , DOI: 10.1021/acs.jpcc.2c06719
Erika Colin-Ulloa ₁ , Julia L. Martin ₂ , Ryan J. Hanna _{1,

2} , Michelle H. Frasch ₂ , Rebecca R. Ramthun ₂ , Hussein O. Badr ₃ , Joshua R. Uzarski ₄ , Michel W. Barsoum ₃ , Ronald L. Grimm ₂ , Lyubov V. Titova ₁

Affiliation

We recently demonstrated scalable, one-pot syntheses of one-dimensional, titania lepidocrocite microfilaments by reacting Ti-containing water-insoluble, earth-abundant compounds such as TiC, TiB₂, TiN, etc., with tetraalkylammonium hydroxide, TMAOH, for a few days at 85 °C under ambient pressure. The resulting one-dimensional lepidocrocite (1DL) titania-based nanofilaments, NFs, tend to self-align along the [100] growth direction to form microfilaments that sometimes self-align into pseudo-two-dimensional (2D) sheets. With sub-square-nanometer cross sections, the resulting band gap energy, E_g, at 4.0 eV is one of the highest ever reported for a titania material. Despite a large band gap, the nanofilaments exhibit significant absorbance throughout the visible spectrum ascribable to intra-gap defect states based on UV–Vis absorbance data and ultraviolet photoelectron spectroscopy (UPS). UP spectra demonstrate work functions of 4.0 ± 0.3 eV vs vacuum and Fermi energies of 3.8 ± 0.1 eV with respect to the valence band edge. Transient absorption (TA) spectroscopy of the 1DL nanofilament thin films with sub-band-gap, visible-light illumination reveals photoexcitations with lifetimes in excess of nanoseconds. In combination with the established oxidative stability, long-lived visible photoexcitations bring forward possible applications of 1DL nanofilaments in photocatalysis and optoelectronics.

中文翻译：

光学吸收和光电子能谱揭示一维纤铁矿 TiO2 的电子结构

_{我们最近通过使含 Ti 的水不溶性、地球丰富的化合物（如 TiC、TiB 2}、TiN 等）与氢氧化四烷基铵 TMAOH反应，展示了可扩展的一锅法合成一维纤铁矿微丝在 85 °C 环境压力下几天。由此产生的一维纤铁矿 (1DL) 二氧化钛基纳米丝 NF 倾向于沿 [100] 生长方向自对准，形成微丝，有时自对准成伪二维 (2D) 片。具有亚平方纳米的横截面，由此产生的带隙能量，E _g, 4.0 eV 是二氧化钛材料有史以来最高的之一。尽管带隙很大，但纳米丝在整个可见光谱中表现出显着的吸光度，这归因于基于 UV-Vis 吸光度数据和紫外光电子能谱 (UPS) 的间隙内缺陷状态。UP 光谱表明 4.0 ± 0.3 eV 对真空的功函数和 3.8 ± 0.1 eV 的费米能量相对于价带边缘。具有子带隙、可见光照明的 1DL 纳米丝薄膜的瞬态吸收 (TA) 光谱揭示了寿命超过纳秒的光激发。结合已建立的氧化稳定性，长寿命的可见光激发带来了 1DL 纳米丝在光催化和光电子学中的可能应用。

更新日期：2023-04-05

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