Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul, Korea.
J Am Chem Soc. 2011 Sep 28;133(38):14998-5007. doi: 10.1021/ja203388r. Epub 2011 Sep 6.
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 ∼1.18 mmol h(-1) g(-1), which is higher than the O(2) production rate (∼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.
通过带相反电荷的二维纳米片 Zn-Cr 层状双氢氧化物（Zn-Cr-LDH）和层状氧化钛之间的自组装，合成了用于可见光诱导 O(2)生成的介孔层状有序纳米杂化物，具有高活性。两种二维纳米片的层状有序通过粉末 X 射线衍射和截面高分辨率透射电子显微镜得到证明。在层间过程中，组成纳米片的原始面内原子排列和电子结构保持完整。所得的杂化层状纳米杂化物表现出对可见光的强吸收和显著抑制的光致发光信号，表明两个组成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高度多孔堆积结构的形成，通过改变层状钛酸盐/Zn-Cr-LDH 的比例可以控制其多孔性。所得的杂化层状纳米杂化物对于可见光诱导 O(2)生成非常活跃，其生成速率为 ∼1.18 mmol h(-1) g(-1)，高于在相同实验条件下作为最有效的可见光光催化剂之一的原始 Zn-Cr-LDH 材料（∼0.67 mmol h(-1) g(-1)）的 O(2)生成速率。这一结果突出了 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卓越功能。最有趣的是，在杂化过程中，Zn-Cr-LDH 的化学稳定性得到了显著提高，这是由于高度稳定的钛酸盐层对 LDH 晶格的保护。本研究结果清楚地表明，无机二维纳米片之间的层层有序组装不仅有效地提高了组分半导体的光催化活性，而且还合成了具有改善的化学稳定性的新型多孔 LDH 基杂化材料。
