多壁碳纳米管及其对H_2吸附体系的Raman光谱

利用原位和非原位紫外 Raman谱法 ,对以 CH4 为碳源 ,由催化法制备的多壁碳纳米管( MWCNTs) ,K -修饰的该类 MWCNTs,以及它们对 H2 的吸附体系进行了 Raman谱表征 ,观测到可分别归属于类石墨结构的基频模 D和 G以及它们的三阶组合频 ,表面 C-H3基和 C-H2 基等的特征Raman峰 ;H2 在这类碳纳米管上的吸附态包括解离吸附生成表面 C-H3和非解离吸附分子氢 H2 ( a) ;在相同实验条件下 ,K -修饰体系上这两类氢吸附物种的表面浓度都比未经 K -修饰的相应体系高 .

Raman Spectra of MWCNT and K~ -MWCNTs and Their Systems Adsorbing Hydrogen

With an UV Vis Raman System, Raman spectra have been taken on the multi walled carbon nanotubes (MWCNTs) prepared from catalytic composition of methane on a Ni Mg O catalyst, and the K modified MWCNTs, as well as their corresponding systems adsorbing hydrogen under ex situ and in situ experimental conditions. On the MWCNTs, the observed Raman peaks were present at 1 386(ms), 1 577(vs), 4 437(w), 2 875(ms), 2 987(ms), and 3 146 (w) cm -1 ; the former three peaks can be ascribed to the fundamental frequencies D and G of carbon nanotubes as well as their triplet combination frequency respectively; and the latter three peaks may be due to symmetrical and asymmetrical C H stretches of surface C-H 3 group and asymmetrical C H stretch of surface C-H 2 group. On the corresponding H 2 adsorption systems, H 2/MWCNTs and H 2/K MWCNTs, the intensities of the Raman peaks due to the C-H 3 species were significantly enhanced; besides, the Raman peak assignable to H H stretching of adsorbed molecular hydrogen H 2(a) was also observed. The results of comparative Raman investigation of these systems indicated that the modification of K to the MWCNTs would be in favor of an increase in adsorption amount of H 2 on the MWCNTs substrate.