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本文采用程序升温脱附(TPD)技术研究了光沉积方法制备的Pt/TiO_2催化剂经过氧化、还原后氧、氢的脱附行为.光沉积过程中,Pt/TiO_2表面上可以生成大量的吸咐氢,在TPD中脱附;同时Pt/TiO_2表面上化学吸附的水在TPD过程中也可以分解释氢.氧化处理的Pt/TiO_2在TPD过程中于550～750K温区出现氧脱附峰,随着氧化温度升高,脱附峰位向高温移动,经实验证明,这种可脱附活泼氧物种的生成是由样品前身中留存氢引起的.还原处理的Pt/TiO_2在TPD过程中分别在300～600和大于600K出现两个氢脱附峰,认为是由于表面羟基和钛—氢(Ti~(4+)—H~-)物种的分解释氢引起的Pt/TiO_2上活泼氧物种的存在,增加了样品在室温条件下的吸氢量;在中温(473～573K)这种活泼氧物种则和氢发生反应,减少了TPD过程中的脱氢量;Pt/TiO_2在大于673K温度还原,可以消除活泼氧物种的影响.
In this paper, the temperature-programmed desorption (TPD) technique was used to study the desorption behavior of oxygen and hydrogen after the Pt / TiO 2 catalyst prepared by photocatalysis was oxidized and reduced. During the photo-deposition process, a large amount of adsorbed Hydrogen in the TPD desorption; the same time, Pt / TiO 2 surface chemisorption of water in the TPD process can also be decomposed to explain the hydrogen oxidation of Pt / TiO_2 TPD in the 550 ~ 750K temperature oxygen desorption peak appeared, With the increase of the oxidation temperature, the desorption peak moved to high temperature, and the experiment proves that the generation of the desorbed active oxygen species is caused by the retention of hydrogen in the precursor of the sample. The reduction of Pt / TiO_2 in the TPD process Two hydrogen desorption peaks occurred at 300 ~ 600 and more than 600K, which are considered to be due to the decomposition of the hydroxyl and Ti - (Ti ~ (4 +) - H ~) species on the surface of Pt / TiO_2. Which increases the amount of hydrogen absorbed by the sample at room temperature. At the intermediate temperature (473-573K), the active oxygen species reacts with hydrogen to reduce the amount of dehydrogenation in the TPD process. At Pt / TiO 2 temperature of more than 673K Restore, you can eliminate the impact of active oxygen species.