多壁碳纳米管及其对H_2吸附体系的Raman光谱

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

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 .

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.