Mesoporous Layer-by-Layer Ordered Nanohybrids of Layered Double Hydroxide and Layered Metal Oxide: Highly Active Visible Light Photocatalysts with Improved Chemical Stability
Mesoporous Layer-by-Layer Ordered Nanohybrids of Layered Double Hydroxide and Layered Metal Oxide: Highly Active Visible Light Photocatalysts with Improved Chemical Stability
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DOI：
10.1021/ja203388r
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发表时间：
2011-09-28
影响因子：
15
通讯作者：
Hwang, Seong-Ju
中科院分区：
文献类型：
--
作者：
Gunjakar, Jayavant L.;Kim, Tae Woo;Hwang, Seong-Ju
通过带相反电荷的Zn-Cr-层状双氢氧化物（Zn-Cr-LDH）和层状二氧化钛的二维纳米片之间的自组装，合成了具有可见光诱导产生O-2高活性的介孔层状有序纳米杂化材料。粉末X射线衍射和截面高分辨率透射电子显微镜证实了两种二维纳米片的逐层有序性。在层间过程中，组分纳米片的原始面内原子排列和电子结构保持完整。所得到的异质层状纳米杂化物显示出对可见光的强吸收和显著降低的光致发光信号，表明两个组分纳米片之间存在有效的电子耦合。二维无机纳米片之间的自组装导致形成高度多孔的堆叠结构，其孔隙率可通过改变层状钛酸盐/Zn-Cr-LDH的比例来控制。所得的异质层状纳米杂化物对于可见光诱导的O-2产生相当活跃，其速率接近1.18 mmol h（-1）g（-1），高于O-2产生速率（类似于0.67 mmol h（-1）g（-1）），即用于O-2产生的最有效的可见光催化剂之一，在相同的实验条件下。该结果突出了Zn-Cr-LDH层状钛酸盐纳米杂化物作为高效可见光活性光催化剂的优异功能性。最重要的是，Zn-Cr-LDH的化学稳定性在杂化后显著提高，这是高度稳定的钛酸盐层保护LDH晶格的结果。本研究结果清楚地表明，无机2D纳米片之间的逐层有序组装不仅在提高组分半导体的光催化活性方面非常有效，而且在合成具有改进的化学稳定性的新型多孔LDH基杂化材料方面也非常有效。
Mesoporous layer-by-layer ordered nanohybrids highly active for visible light-induced O-2 generation are synthesized by self-assembly between oppositely charged 2D nanosheets of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) and layered titanium oxide. The layer-by-layer ordering of two kinds of 2D nanosheets is evidenced by powder X-ray diffraction and cross-sectional high resolution-transmission electron microscopy. Upon the interstratification process, the original in-plane atomic arrangements and electronic structures of the component nanosheets remain intact. The obtained heterolayered nanohybrids show a strong absorption of visible light and a remarkably depressed photoluminescence signal, indicating an effective electronic coupling between the two component nanosheets. The self-assembly between 2D inorganic nanosheets leads to the formation of highly porous stacking structure, whose porosity is controllable by changing the ratio of layered titanate/Zn-Cr-LDH. The resultant heterolayered nanohybrids are fairly active for visible light-induced O-2 generation with a rate of similar to 1.18 mmol h(-1) g(-1), which is higher than the O-2 production rate (similar to 0.67 mmol h(-1) g(-1)) by the pristine Zn-Cr-LDH material, that is, one of the most effective visible light photocatalysts for O-2 production, under the same experimental condition. This result highlights an excellent functionality of the Zn-Cr-LDH-layered titanate nanohybrids as efficient visible light active photocatalysts. Of prime interest is that the chemical stability of the Zn-Cr-LDH is significantly improved upon the hybridization, a result of the protection of the LDH lattice by highly stable titanate layer. The present findings clearly demonstrate that the layer-by-layer-ordered assembly between inorganic 2D nanosheets is quite effective not only in improving the photocatalytic activity of the component semiconductors but also in synthesizing novel porous LDH-based hybrid materials with improved chemical stability.