Catalysis with TiO2/gold nanocomposites.: Effect of metal particle size on the Fermi level equilibration
Catalysis with TiO2/gold nanocomposites.: Effect of metal particle size on the Fermi level equilibration
复制标题
DOI：
10.1021/ja0315199
复制
发表时间：
2004-04-21
影响因子：
15
通讯作者：
Kamat, PV
中科院分区：
文献类型：
--
作者：
Subramanian, V;Wolf, EE;Kamat, PV
当光激发的半导体纳米颗粒与金属纳米颗粒接触时，它们经历电荷平衡。这样的电荷分布通过将费米能级移动到更负的电势而在指示复合材料的能量学方面具有直接影响。电子转移到Au纳米粒子，现在已经探测到通过激发TiO 2纳米粒子在稳态和激光脉冲激发。用C-60/C-60（-）氧化还原电对进行平衡提供了一种测定TiO 2-Au复合体系表观费米能级的方法。TiO 2-Au复合物的表观费米能级的尺寸依赖性位移（8 nm直径为20 mV，5 nm为40 mV，3 nm金纳米颗粒为60 mV）显示了Au纳米颗粒通过改善光致电荷分离来影响能量学的能力。从UV激发的TiO 2-> Au -> C-60中分离出单个电荷转移步骤，提供了关于金属在催化剂辅助的纳米复合物中的作用以及金属-半导体纳米复合物的尺寸依赖的催化活性的机理和动力学信息。
Photoexcited semiconductor nanoparticles undergo charge equilibration when they are in contact with metal nanoparticles. Such a charge distribution has direct influence in dictating the energetics of the composite by shifting the Fermi level to more negative potentials. The transfer of electrons to Au nanoparticles has now been probed by exciting TiO2 nanoparticles under steady-state and laser pulse excitation. Equilibration with the C-60/C-60(-) redox couple provides a means to determine the apparent Fermi level of the TiO2-Au composite system. The size-dependent shift in the apparent Fermi level of the TiO2-Au composite (20 mV for 8-nm diameter and 40 mV for 5-nm and 60 mV for 3-nm gold nanoparticles) shows the ability of Au nanoparticles to influence the energetics by improving the photoinduced charge separation. Isolation of individual charge-transfer steps from UV-excited TiO2 --> Au --> C-60 has provided mechanistic and kinetic information on the role of metal in semiconductor-assisted photocatalysis and size-dependent catalytic activity of metal-semiconductor nanocomposites.