Franking Ryan A, Landis Elizabeth C, Hamers Robert J
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Langmuir. 2009 Sep 15;25(18):10676-84. doi: 10.1021/la901116c.
Well-defined molecular layers can be formed on the surface of nanocrystalline anatase TiO2 by photochemically grafting organic molecules bearing a terminal vinyl group. The molecular layers produced are shown to have minimal oxidation and are able to be patterned and uniformly grafted through optically thick nanocrystalline films. Stability tests show that the layers have excellent stability in deionized water at 80 degrees C, aqueous solutions at pH=1.0 and pH=10.3 at 65 degrees C, and acetonitrile for time scales approaching 1200 h. Degradation of the films in deionized water occurs using a AM1.5 full-spectrum solar simulator as an illumination source but is partially suppressed by filtering with a 400 nm UV blocking filter which blocks the above-bandgap light. A mechanism is proposed for the grafting reaction in which the surface hydroxyl groups trap photoexcited holes, facilitating reaction with the vinyl group.
通过光化学接枝带有末端乙烯基的有机分子，可以在纳米晶锐钛矿型TiO₂表面形成明确的分子层。所产生的分子层显示出最小程度的氧化，并且能够通过光学厚度的纳米晶薄膜进行图案化和均匀接枝。稳定性测试表明，这些分子层在80℃的去离子水中、65℃时pH = 1.0和pH = 10.3的水溶液中以及乙腈中在接近1200小时的时间尺度上具有优异的稳定性。使用AM1.5全光谱太阳模拟器作为照明源时，薄膜在去离子水中会发生降解，但通过用400 nm紫外线阻挡滤光片过滤来部分抑制降解，该滤光片可阻挡带隙以上的光。提出了一种接枝反应的机制，其中表面羟基捕获光激发的空穴，促进与乙烯基的反应。
