Department of Chemistry, The University of Auckland, Auckland, New Zealand.
Langmuir. 2010 May 4;26(9):6411-7. doi: 10.1021/la9040985.
The reaction of acetic acid with stoichiometric and reduced rutile TiO(2)(011) single-crystal surfaces has been studied under dark and UV illumination conditions. The surface coverage after the dissociative adsorption of acetic acid with respect to Ti was found to be 0.55. Monitoring XPS Ti, O, and C lines revealed that the surface population decreased incrementally with temperature up to 650 K. The decrease in the slope of both the -CH(3)- and -COO- XPS peaks was not monotonic and followed two slopes in agreement with TPD results. The first channel involves the removal of surface acetates to acetic acid by recombinative desorption, and the second mainly involves dehydration to ketene. UV-light illumination was conducted at 300 K in the absence and presence of molecular oxygen at different pressures: in the 10(-6)-10(-9) Torr range. Acetate species were found to decrease with illumination time, and their decrease is seen to be dependent on the oxygen pressure. Plausible decomposition pathways are presented. Deliberately reducing the surface by electron bombardment prior to the adsorption of acetic acid did not affect the photoreaction rate within the experimental limits.
已在黑暗和紫外光照条件下研究了化学计量和还原金红石 TiO(2)(011)单晶表面与乙酸的反应。发现乙酸在 Ti 上的离解吸附后，表面覆盖率为 0.55。监测 XPS Ti、O 和 C 线表明，表面浓度随温度升高至 650 K 而逐渐降低。-CH(3)-和-COO- XPS 峰斜率的降低不是单调的，与 TPD 结果一致，有两个斜率。第一个通道涉及通过重组脱附将表面乙酸盐去除为乙酸，第二个通道主要涉及脱水生成烯酮。在不同压力下（10(-6)-10(-9)托范围），在 300 K 下进行了紫外光照射，在有无分子氧的情况下进行。发现随着光照时间的延长，乙酸盐的含量会减少，而且其减少程度取决于氧气压力。提出了合理的分解途径。在吸附乙酸之前通过电子束故意还原表面，在实验范围内不会影响光反应速率。
