O_2在Si掺杂石墨烯上吸附与活化

采用包含色散力校正的密度泛函理论方法(DFT-D)研究了O2在Si掺杂石墨烯(Si-Gra)上吸附与活化.研究结果表明:1)与纯净石墨烯相比,Si掺杂极大的增强了石墨烯对O2的吸附能力.O2的最稳定吸附构型是以Side-on模式吸附在掺杂的Si的顶位,形成O-Si-O三元环.次稳定吸附构型是与Si及近邻的一个C形成O-Si-C-O四元环结构.两个吸附构型对应的吸附能分别为-2.40和-1.93eV;2)O2有两种分解路径:直接分解路径(势垒为0.53eV)和整体扩散后的分解路径(势垒为0.81eV);3)分解之后的两个O原子分别吸附在Si的顶位和相邻碳环的两个碳原子的桥位;4)电子结构分析表明吸附的O2从Si-Gra获得较多电荷,从而被活化.总之,Si-Gra具有较强的催化氧气还原能力,是一种潜在的良好的非金属氧还原催化剂.

The adsorption and activation of the O2 on the Si-doped graphene

Density functional theory with dispersion-corrected density functional theory (DFT-D) calculations are performed to study the mechanism of O2 adsorption and activation on Si-doped grapheme (Si-Gra). It is found that: 1) compared with the pristine graphene, the Si doped graphene enhance the O2 adsorption. The most stable O2 adsorption is on the top of Si with the side-on configuration, resulting in the O-Si-O three member ring; the second most stable O2 adsorption is on the bridge site of Si and its neighbor C with the O-Si-C-O four member ring. The corresponding adsorption energies are -2.40 and -1.93 eV, respectively. 2) two kinds of decomposition paths are presented, the directly decomposition path and diffusion path with the energy barriers of 0.53 eV and 0.81 eV, respectively; 3) the two atomic O (dissociated from O2 molecular) anchor on the top of Si and the bridge site of two C atoms, respectively; 4) the activation of the O2 on the Si-Gra is from the big charge transfer between O2 and the Si-Gra support. Summarily, Si-Gra can probably serve as good and metal-free catalysts for oxygen reduction reaction.