Luo Mingming, Liang Zhao, Liu Chao, Qi Xiaopeng, Chen Mingwei, Yang Hui, Liang Tongxiang
Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology Ganzhou 341000 China
RSC Adv. 2020 Jul 27;10(46):27856-27863. doi: 10.1039/d0ra05287f. eCollection 2020 Jul 21.
The CO oxidation mechanisms over three different MnN-doped graphene (MnNC: MnNC-hex, MnNC-opp, MnNC-pen) structures were investigated through first-principles calculations. The vacancy in graphene can strongly stabilize Mn atoms and make them positively charged, which promotes O activation and weakens CO adsorption. Hence, CO oxidation activity is enhanced and the catalyst is prevented from being poisoned. CO oxidation reaction (COOR) on MnNC along the Eley-Rideal (ER) mechanism and the Langmuir-Hinshelwood (LH) mechanism will leave one O atom on the Mn atom, which is difficult to react with isolated CO. COOR on MnNC-opp along the ER mechanism and termolecular Eley-Rideal (TER) mechanism need overcome low energy barriers in the rate limiting step (RLS), which are 0.544 and 0.342 eV, respectively. The oxidation of CO along TER mechanism on MnNC-opp is the best reaction pathway with smallest energy barrier. Therefore, the MnNC-opp is an efficient catalysis and this study has a guiding role in designing effective catalyst for CO oxidation.
通过第一性原理计算研究了三种不同的MnN掺杂石墨烯（MnNC：MnNC-六方、MnNC-反位、MnNC-锯齿）结构上的CO氧化机理。石墨烯中的空位可以强烈地稳定Mn原子并使其带正电，这促进了O的活化并减弱了CO的吸附。因此，CO氧化活性增强，催化剂中毒得到抑制。MnNC上沿Eley-Rideal（ER）机理和Langmuir-Hinshelwood（LH）机理的CO氧化反应（COOR）会在Mn原子上留下一个O原子，该O原子难以与孤立的CO发生反应。MnNC-反位上沿ER机理和三分子Eley-Rideal（TER）机理的COOR在速率限制步骤（RLS）中需要克服的低能垒分别为0.544和0.342 eV。MnNC-反位上沿TER机理的CO氧化是具有最小能垒的最佳反应途径。因此，MnNC-反位是一种高效催化剂，本研究对设计用于CO氧化的有效催化剂具有指导作用。
