Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, CAS Key Laboratory of Materials for Energy Conversion and Laboratory of Engineering and Material Science, University of Science and Technology of China, Hefei, Anhui 230026 (P.R. China) http://staff.ustc.edu.cn/∼yjxiong/
Angew Chem Int Ed Engl. 2014 Mar 17;53(12):3205-9. doi: 10.1002/anie.201309660. Epub 2014 Feb 12.
The charge state of the Pd surface is a critical parameter in terms of the ability of Pd nanocrystals to activate O2 to generate a species that behaves like singlet O2 both chemically and physically. Motivated by this finding, we designed a metal-semiconductor hybrid system in which Pd nanocrystals enclosed by {100} facets are deposited on TiO2 supports. Driven by the Schottky junction, the TiO2 supports can provide electrons for metal catalysts under illumination by appropriate light. Further examination by ultrafast spectroscopy revealed that the plasmonics of Pd may force a large number of electrons to undergo reverse migration from Pd to the conduction band of TiO2 under strong illumination, thus lowering the electron density of the Pd surface as a side effect. We were therefore able to rationally tailor the charge state of the metal surface and thus modulate the function of Pd nanocrystals in O2 activation and organic oxidation reactions by simply altering the intensity of light shed on Pd-TiO2 hybrid structures.
钯表面的荷电状态是钯纳米晶体激活 O2 的能力的一个关键参数，这可以生成一种在化学和物理性质上都类似于单重态 O2 的物质。受此发现的启发，我们设计了一种金属-半导体混合系统，其中 {100} 面封闭的钯纳米晶体沉积在 TiO2 载体上。在肖特基结的驱动下，TiO2 载体可以在适当的光照射下为金属催化剂提供电子。通过超快光谱的进一步检测表明，在强光照下，钯的等离激元可能迫使大量电子从 Pd 反向迁移到 TiO2 的导带，从而降低 Pd 表面的电子密度，这是一个副作用。因此，我们能够通过简单地改变照射在 Pd-TiO2 混合结构上的光强，来合理地调节金属表面的电荷状态，从而调节 Pd 纳米晶体在 O2 激活和有机氧化反应中的功能。
