O_2在FeN_4掺杂碳纳米管上氢化特性的密度泛函理论研究

Density functional theory investigations of O_2 hydrogenation on FeN_4 doped carbon nanotubes

因其速率快、稳定性高,非金属N与金属共掺杂的碳材料作为新型高效ORR催化剂而引起了人们的广泛关注.采用包含色散力校正的密度泛函理论方法系统地研究了氧分子在FeN_4掺杂的碳纳米管上的吸附、氢化特性.结果表明:(1)O_2倾向于以end-on模式吸附在Fe顶位,O-O键与衬底表面成一定角度,并指向五元环,对应的吸附能为1.62 e V.(2)O_2在FeN_4-CNTs上更倾向于直接氢化为OOH,然后解离为O+OH,整个路径的限速步为OOH的解离,对应的势垒为1.19 eV.

Metal-coordinated nitrogen-doped carbon materials are attractive with high stability as alternative and efficient catalysts in oxygen reduction reaction （ORR）. Density functional theory including dispersion corrections （DFT-D） is preformed to study the mechanisms of O2 adsorption and hydrogenation on FeN4 doped carbon nanotubes （FeN4-CNTs）. It is found that： （1） O2 tends to stay on the top of the Fe with the end-on configuration, oxygen-oxygen bonds obliquely adsorbing on the surface and pointing to the five member ring. The corresponding adsorption energy is 1.62 eV. （2） O2 prefers to be hydrogenated directly into OOH on the FeN4-CNTs, and then to decompose into O ＋ OH. The path rate-limiting step is the decomposition of the O2 with the reaction barrier of 1.19 eV.