Defect-engineering of mesoporous TiO2 microspheres with phase junctions for efficient visible-light driven fuel production
Defect-engineering of mesoporous TiO2 microspheres with phase junctions for efficient visible-light driven fuel production
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具有相连接的介孔 TiO2 微球的缺陷工程，用于有效的可见光驱动燃料生产
DOI：
10.1016/j.nanoen.2019.104113
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发表时间：
2019
期刊：
影响因子：
17.6
通讯作者：
Zhao Dongyuan
中科院分区：
文献类型：
--
作者：
Zhang Wei;He Haili;Tian Yong;Li Haoze;Lan Kun;Zu Lianhai;Xia Yuan;Duan Linlin;Li Wei;Zhao Dongyuan
TiO2材料的缺陷工程是增强其光吸收的有效方法。然而，由于缺陷位置不可控，可见光区域的活性仍远不能令人满意。在此，我们展示了一种简便的限制还原路线，通过使用硼氢化钠（NaBH4）作为还原剂，向具有相连接的介孔TiO2微球（表示为M-TiO2-PJs）引入可控缺陷。在这种情况下，介孔通道对NaBH4的限域分解作用使得在温和的反应条件下更有效地产生缺陷，从而使介孔TiO2微球能够良好地保留介孔和相连接结构。此外，通过改变还原温度，缺陷从纳米晶暴露表面迁移到相结界面，从而可以很好地调整缺陷的位置。在300°C还原后，所得有缺陷的介孔TiO2微球表现出良好的介孔结构、高表面积（~75.6m2g-1）、大孔体积（0.36cm3g-1）、轻微无序的表面和紧密接触的锐钛矿-金红石界面，表现出最先进的光催化水分解活性。在可见光（λ>400nm）下，氢气生成率高达42.6μmolh–1（基于50mg催化剂），在420和520nm处的表观量子效率分别为12.7%和2.8%，是迄今为止报道的TiO2基光催化剂中的最佳值。我们还表明，由于缺陷对CO2分子的活化和吸附作用，缺陷介孔TiO2微球在可见光下具有超强的CH4选择性（57%）和CO2还原产率（15nmolh-1）。这项工作为高性能光催化剂的合理设计提供了新的见解。
Defect-engineering of TiO2materials is an effective way to enhance their light absorption. However, activities in the visible-light region are still far from satisfactory due to the uncontrollable defect location. Herein, we demonstrate a facile confinement reduction route to introduce controllable defects to mesoporous TiO2microspheres with phase junctions (denoted as M-TiO2-PJs) by using sodium borohydride (NaBH4) as the reducing agent. In this case, the confinement decomposition effect of mesopore channels over NaBH4enables the generation of defects more effectively at a mild reaction condition, enabling the well-retained mesoporous and phase junction structures of mesoporous TiO2microspheres. Moreover, by changing the reduction temperature, the defects are migrated from the nanocrystalline-exposed surfaces to phase junction interfaces, enabling that the location of the defects can be well-tuned. After the reduction at 300 °C, the resultant defective mesoporous TiO2microspheres show the well-retained mesostructure, high surface areas (~75.6 m2g-1), large pore volumes (0.36 cm3g-1), slightly disordered surfaces and intimately contacted anatase-rutile interfaces, which exhibit the state-of-the-art activities for photocatalytic water splitting. The H2generation rate is as high as 42.6 μmol h–1(based on 50 mg of catalyst) under visible-light (λ > 400 nm) and the apparent quantum efficiencies are estimated to be 12.7% and 2.8% at 420 and 520 nm, respectively, which are the best values among TiO2-based photocatalysts reported to date. We also show that the defective mesoporous TiO2microspheres possess a super CH4selectivity (57%) and yield (15 nmol h-1) for CO2reduction under visible-light because of the activation and adsorption effect of defects for CO2molecules. This work provides new insight into rational design of high performance photocatalysts.