Mo掺杂的TiO2：对氧空位、锐钛矿相稳定性和光催化活性的影响,Journal of Physics: Materials

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Mo掺杂的TiO2：对氧空位、锐钛矿相稳定性和光催化活性的影响
Journal of Physics: Materials ( IF 4.9 ) Pub Date : 2020-03-31 , DOI: 10.1088/2515-7639/ab749c
Vignesh Kumaravel _{1,

2} , Stephen Rhatigan ₃ , Snehamol Mathew _{1,

2} , Marie Clara Michel ₃ , John Bartlett _{1,

2} , Michael Nolan ₃ , Steven J Hinder ₄ , Antonio Gasc ₅ , Csar Ruiz-Palomar ₆ , Daphne Hermosilla ₆ , Suresh C Pillai _{1,

2}

Affiliation

摘要这项工作概述了钼 (Mo) 掺杂对二氧化钛氧空位形成和光催化活性影响的实验和理论研究。采用 X 射线衍射 (XRD)、拉曼光谱、X 射线光电子能谱 (XPS) 和光致发光 (PL) 等分析技术探测 Mo 掺杂 TiO2 的锐钛矿向金红石转变 (ART)、表面特征和光学特性。 Mo-TiO2)。XRD 结果表明，在 750 °C 下，2 mol% Mo 掺杂有效地阻碍了 ART，产生了 67% 的锐钛矿和 33% 的金红石。此外，通过与氧空位和 Ti-O 键的相互作用，Mo 掺杂会影响 TiO2 的晶体生长。XPS 结果证实了 Ti-O-Mo 和 Mo-Ti-O 键的形成。声子限制，通过拉曼分析验证了晶格应变和非化学计量缺陷。DFT结果表明，在锐钛矿Ti位点置换掺杂Mo后，Mo氧化态为Mo6+，空Mo-s态出现在二氧化钛导带最小值处。空的 Mo-d 状态与 DOS 图中的锐钛矿导带重叠。通过形成氧空位来减少 Mo-TiO2 需要大量的能量成本，与原始锐钛矿计算的能量成本相当。Mo5+ 和 Ti3+ 在氧空位形成后存在，并且由于这些还原的阳离子出现在二氧化钛主体的能隙中，占据状态。PL 研究表明，Mo-TiO2 中的电子-空穴复合过程明显低于 TiO2 锐钛矿和金红石。这归因于 Mo 掺杂剂在 TiO2 的 CB 下方引入了 5s 间隙态。此外，光生电荷载流子可以很容易地被 Mo6+ 和 Mo5+ 离子捕获并定位在 TiO2 表面，从而提高光催化活性。

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Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Abstract This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO2. Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO2 (Mo–TiO2). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750 °C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti–O bond. The formation of Ti–O–Mo and Mo–Ti–O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo–TiO2 through oxygen vacancy formation. Mo5+ and Ti3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron–hole recombination process in Mo–TiO2 was exceptionally lower than that of TiO2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO2 surface by Mo6+ and Mo5+ ions to improve the photocatalytic activity.

更新日期：2020-03-31

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