Jiang Quanguo, Zhang Jianfeng, Ao Zhimin, Huang Huajie, He Haiyan, Wu Yuping
College of Mechanics and Materials, Hohai University, Nanjing, China.
Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, China.
Front Chem. 2018 May 29;6:187. doi: 10.3389/fchem.2018.00187. eCollection 2018.
The CO oxidation mechanism on graphene with divacancy (DG) embedded with transition metal from Sc to Zn has been studied by using first principles calculations. The results indicate that O molecule is preferentially adsorbed on Sc, Ti, V, Cr, Mn, and Fe-DG, which can avoid the CO poisoning problem that many catalysts facing and is beneficial to the CO oxidation progress. Further study indicates that Mn-DG shows the best catalytic properties for CO oxidation with consideration of both Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) oxidation mechanisms. Along the ER mechanism, the reaction energy barrier for the first step (CO + O → OOCO) is 0.96 eV. Along the LH mechanism, the energy barrier for the rate limiting step (CO + O → OOCO) is only 0.41 eV, indicating that the CO oxidation on Mn-DG will occur along LH mechanism. The Hirshfeld charge distributions of O and CO molecules is tuned by the embedded Mn atom, and the charge transfer from the embedded Mn atom to the adsorbed molecules plays an important role for the CO oxidation. The result shows that the Mn-embedded divacancy graphene is a noble-metal free and efficient catalyst for CO oxidation at low temperature.
通过第一性原理计算研究了嵌入从钪到锌的过渡金属的双空位石墨烯（DG）上的CO氧化机理。结果表明，O分子优先吸附在Sc、Ti、V、Cr、Mn和Fe-DG上，这可以避免许多催化剂面临的CO中毒问题，有利于CO氧化进程。进一步研究表明，考虑到朗缪尔-欣谢尔伍德（LH）和埃利-里德（ER）氧化机理，Mn-DG对CO氧化表现出最佳的催化性能。沿着ER机理，第一步（CO + O → OOCO）的反应能垒为0.96 eV。沿着LH机理，限速步骤（CO + O → OOCO）的能垒仅为0.41 eV，表明Mn-DG上的CO氧化将沿着LH机理发生。嵌入的Mn原子调节了O和CO分子的赫希菲尔德电荷分布，嵌入的Mn原子向吸附分子的电荷转移对CO氧化起着重要作用。结果表明，嵌入Mn的双空位石墨烯是一种低温下无贵金属且高效的CO氧化催化剂。
