Cocatalyst-Free Photocatalysts for Efficient Visible-Light-Induced H2 Production: Porous Assemblies of CdS Quantum Dots and Layered Titanate Nanosheets
Cocatalyst-Free Photocatalysts for Efficient Visible-Light-Induced H2 Production: Porous Assemblies of CdS Quantum Dots and Layered Titanate Nanosheets
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DOI：
10.1002/adfm.201100453
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发表时间：
2011-08-23
影响因子：
19
通讯作者：
Hwang, Seong-Ju
中科院分区：
文献类型：
--
作者：
Kim, Hyo Na;Kim, Tae Woo;Hwang, Seong-Ju
新型复合光催化剂可以在没有铂助催化剂的情况下实现高效的可见光诱导氢气的产生。在这种光催化剂中，将尺寸约为2.5 nm的硫化镉量子点(QDS)引入到亚纳米厚度的层状钛酸盐纳米片的多孔性组装中。由于组元半导体的晶体尺寸非常有限，使得CdS量子点的电子结构与层状钛酸盐纳米片的电子结构强烈耦合，导致两者之间有效的电子转移，从而提高了CDS的光稳定性。由于促进了电子转移，使杂化后的CdS量子点的光致发光几乎被猝灭，这表明电子-空穴复合几乎被抑制。这些无铂助催化剂的层状钛酸镉纳米杂化材料比前驱体硫化镉量子点和层状钛酸盐纳米杂化材料表现出更高的光催化活性，这是由于杂化后电子和空穴寿命的延长、禁带能量的降低和比表面积的扩大。这些无铂杂化材料的光催化效率(约1.0mmolg(-1)h(-1))远远高于其他无铂的硫化镉-二氧化钛体系的光催化效率。这一发现突显了2D半导体纳米片作为有效构建块来探索高效可见光活性光催化剂生产H-2的有效性。
Highly effi cient, visible-light-induced H-2 generation can be achieved without the help of a Pt cocatalyst by new hybrid photocatalysts, in which CdS quantum dots (QDs) (particle size approximate to 2.5 nm) are incorporated in the porous assembly of sub-nanometer-thick layered titanate nanosheets. Due to the very-limited crystal dimension of component semiconductors, the electronic structure of CdS QDs is strongly coupled with that of the layered titanate nanosheets, leading to an effi cient electron transfer between them and the enhancement of the CdS photostability. As a consequence of the promoted electron transfer, the photoluminescence of CdS QDs is nearly quenched after hybridization, indicating the almost-suppression of electron-hole recombination. These Pt-cocatalyst-free, CdS-layered titanate nanohybrids show much-higher photocatalytic activity for H-2 production than the precursor CdS QDs and layered titanate, which is due to the increased lifetime of the electrons and holes, the decrease of the bandgap energy, and the expansion of the surface area upon hybridization. The observed photocatalytic efficiency of these Pt-free hybrids (approximate to 1.0 mmol g(-1) h(-1)) is much greater than reported values of other Pt-free CdS-TiO2 systems. This finding highlights the validity of 2D semiconductor nanosheets as effective building blocks for exploring effi cient visible-light-active photocatalysts for H-2 production.