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Red-Shifted Absorptions of Cation-Defective and Surface-Functionalized Anatase with Enhanced Photoelectrochemical Properties
ACS Omega ( IF 3.7 ) Pub Date : 2019-06-24 00:00:00 , DOI: 10.1021/acsomega.9b01219 Jiwei Ma 1, 2 , Wei Li 2 , Nikolay T. Le 3 , Jesús A. Díaz-Real 4 , Monique Body 5 , Christophe Legein 5 , Jolanta Światowska 6 , Arnaud Demortière 7, 8 , Olaf J. Borkiewicz 9 , Elizaveta A. Konstantinova 3, 10 , Alexander I. Kokorin 11 , Nicolas Alonso-Vante 4 , Christel Laberty-Robert 8, 12 , Damien Dambournet 2, 8
ACS Omega ( IF 3.7 ) Pub Date : 2019-06-24 00:00:00 , DOI: 10.1021/acsomega.9b01219 Jiwei Ma 1, 2 , Wei Li 2 , Nikolay T. Le 3 , Jesús A. Díaz-Real 4 , Monique Body 5 , Christophe Legein 5 , Jolanta Światowska 6 , Arnaud Demortière 7, 8 , Olaf J. Borkiewicz 9 , Elizaveta A. Konstantinova 3, 10 , Alexander I. Kokorin 11 , Nicolas Alonso-Vante 4 , Christel Laberty-Robert 8, 12 , Damien Dambournet 2, 8
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Manipulating the atomic structure of semiconductors is a fine way to tune their properties. The rationalization of their modified properties is, however, particularly challenging as defects locally disrupt the long-range structural ordering, and a deeper effort is required to fully describe their structure. In this work, we investigated the photoelectrochemical properties of an anatase-type structure featuring a high content of titanium vacancies stabilized by dual-oxide substitution by fluoride and hydroxide anions. Such atomic modification induces a slight red-shift band gap energy of 0.08 eV as compared to pure TiO2, which was assigned to changes in titanium–anion ionocovalent bonding. Under illumination, electron paramagnetic resonance spectroscopy revealed the formation of TiIII and O2– radicals which were not detected in defect-free TiO2. Consequently, the modified anatase shows higher ability to oxidize water with lower electron–hole recombination rate. To further increase the photoelectrochemical properties, we subsequently modified the compound by a surface functionalization with N-methyl-2-pyrrolidone (NMP). This treatment further modifies the chemical composition, which results in a red shift of the band gap energy to 3.03 eV. Moreover, the interaction of the NMP electron-donating molecules with the surface induces an absorption band in the visible region with an estimated band gap energy of 2.25–2.50 eV. Under illumination, the resulting core–shell structure produces a high concentration of reduced TiIII and O2–, suggesting an effective charge carrier separation which is confirmed by high photoelectrochemical properties. This work provides new opportunities to better understand the structural features that affect the photogenerated charge carriers.
中文翻译：
具有增强的光电化学特性的阳离子缺陷型和表面功能化锐钛矿的红移吸收
操纵半导体的原子结构是调整其性能的一种好方法。但是，由于缺陷会局部破坏长程结构的有序性，因此合理地修改其修饰的属性尤其具有挑战性，并且需要更深入的努力来完整描述它们的结构。在这项工作中，我们研究了具有高含量钛空位的锐钛矿型结构的光电化学性质，该钛空位通过氟化物和氢氧根阴离子的双氧化物取代而稳定。与纯TiO 2相比，这种原子修饰引起的红移带隙能量为0.08 eV ，这与钛-阴离子离子共价键的变化有关。在光照下，电子顺磁共振波谱揭示了Ti III的形成和O 2 -其中未以TiO无缺陷的检测基团2。因此，改性的锐钛矿具有较高的氧化水的能力，具有较低的电子-空穴复合率。为了进一步提高光电化学性质，我们随后通过用N-甲基-2-吡咯烷酮（NMP）进行表面官能化来修饰该化合物。该处理进一步改变了化学组成，这导致带隙能量红移至3.03 eV。此外，NMP给电子分子与表面的相互作用在可见光区域感应出吸收带，估计带隙能量为2.25–2.50 eV。在光照下，最终的核-壳结构产生高浓度的还原钛III和O 2 –，表明有效的载流子分离得到了高度的光电化学性能的证实。这项工作为更好地理解影响光生电荷载流子的结构特征提供了新的机会。
更新日期：2019-06-24
中文翻译：
具有增强的光电化学特性的阳离子缺陷型和表面功能化锐钛矿的红移吸收
操纵半导体的原子结构是调整其性能的一种好方法。但是，由于缺陷会局部破坏长程结构的有序性，因此合理地修改其修饰的属性尤其具有挑战性，并且需要更深入的努力来完整描述它们的结构。在这项工作中，我们研究了具有高含量钛空位的锐钛矿型结构的光电化学性质，该钛空位通过氟化物和氢氧根阴离子的双氧化物取代而稳定。与纯TiO 2相比，这种原子修饰引起的红移带隙能量为0.08 eV ，这与钛-阴离子离子共价键的变化有关。在光照下，电子顺磁共振波谱揭示了Ti III的形成和O 2 -其中未以TiO无缺陷的检测基团2。因此，改性的锐钛矿具有较高的氧化水的能力，具有较低的电子-空穴复合率。为了进一步提高光电化学性质，我们随后通过用N-甲基-2-吡咯烷酮（NMP）进行表面官能化来修饰该化合物。该处理进一步改变了化学组成，这导致带隙能量红移至3.03 eV。此外，NMP给电子分子与表面的相互作用在可见光区域感应出吸收带，估计带隙能量为2.25–2.50 eV。在光照下，最终的核-壳结构产生高浓度的还原钛III和O 2 –，表明有效的载流子分离得到了高度的光电化学性能的证实。这项工作为更好地理解影响光生电荷载流子的结构特征提供了新的机会。
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