Photoinduced Desorption of Sulfur from Nobel Metal Nanoparticles Loaded on Semiconductors

动力学分析表明，硫从负载在TiO_2颗粒上的金纳米颗粒上的光诱导脱附反应的速率常数随pH值的增加而增加。我们的光电化学测量和密度泛函理论（DFT）计算表明，该反应是由于金纳米颗粒的费米能随辐照而上移所致。采用溶胶-凝胶法在玻璃衬底上制备了锐钛矿型TiO_2薄膜。采用沉积-沉淀法在TiO_2薄膜（Au/TiO_2-TF）和TiO_2颗粒（Au/TiO_2-P）表面制备了高度分散的纳米金颗粒。Au/TiO_2-TF吸附S_8分子中的硫的X射线光电子能谱表明，S_8分子以原子和分子两种化学吸附方式（S-Au/TiO_2-TF）选择性地吸附在Au表面。在<ex>298 K的水中，S-Au/TiO 2-TF和S-Au/TiO 2-P在光照射（λ&gt; 300 nm）下，硫的脱附量基本保持Au的粒径。动力学分析表明，在开放反应体系中S-Au/TiO_2-TF的硫解吸速率常数比在封闭反应体系中S-Au/TiO_2-P的硫解吸速率常数大约1倍。3.6.

Kinetic analysis of the photoinduced desorption of sulfur from gold nanoparticles loaded on TiO_2 particles in water has revealed a rate constant increase with increasing pH. Our photoelectrochemical measurements and density functional theoretical (DFT) calculations have led us to the conclusion that this reaction results from an upward shift in the Fermi energy of gold nanoparticles with irradiation. Anatase-type TiO_2 films were formed on SiO_2 film-coated glass substrates by a sol-gel method. Nanometer-sized gold particles were highly dispersed on the surfaces of the TiO_2 film (Au/TiO_2-TF) and TiO_2 particles (Au/TiO_2-P) using a deposition-precipitation method. X-ray photoelectron spectra of Au/TiO_2-TF adsorbed with sulfur from S_8 molecules indicated that the sulfurs are selectively adsorbed on the Au surfaces with the two kinds of chemisorption modes, atomic and molecular adsorption (S-Au/TiO_2-TF). Light-irradiation (λ_<ex> > 300 nm) to S-Au/TiO_2-TF and S-Au/TiO_2-P in water at 298 K gave rise to desorption of the sulfur with the Au particle size almost maintained. Kinetic analysis showed that the rate constant for the sulfur desorption from S-Au/TiO_2-TF in an opened reaction system is larger than that from S-Au/TiO_2-P in a closed reaction system by a factor of ca. 3.6.