Active Sites in Graphene and the Mechanism of CO2 Formation in Carbon Oxidation

被引:182
作者
Radovic, Ljubisa R. [1 ,2 ]
机构
[1] Penn State Univ, Dept Energy & Mineral Engn, University Pk, PA 16802 USA
[2] Univ Concepcion, Dept Chem Engn, Concepcion, Chile
关键词
SURFACE-CHEMISTRY; OXYGEN-ADSORPTION; MOLECULAR-OXYGEN; BENZENE OXIDE; GRAPHITE; GASIFICATION; REDUCTION; EVOLUTION; KINETICS; OXEPIN;
D O I
10.1021/ja904731q
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Over the past decade we have witnessed a steady rise in contributions of computational quantum chemistry to the understanding of reactivity of carbon materials. Several litmus tests must be applied to this evolving body of work before it can be viewed with a sufficient degree of confidence. The results of a crucial test are presented here: formulation of thermodynamically and kinetically plausible paths for CO2 formation in the deceivingly simple reaction C + (1 - y/2)O-2 = (1 - y)O-2 + yCO. A mechanism is proposed that clarifies the nature of atoms responsible for adsorption and reaction of molecular oxygen on the surface of Sp(2)-hybridized carbons, both flat and curved, and is also consistent with the postulate that the (re)active sites are carbene- and carbyne-type carbon atoms at graphene edges. Using density functional theory and representative two-dimensional graphene clusters, a direct and an indirect route to CO2 formation were identified as both necessary and sufficient to account for key experimental observations. The former involves single-site O-2 adsorption on carbene-type zigzag edges. The latter includes the presence of mobile epoxide-type oxygen on the basal plane and its insertion into an edge hexagon, analogous to the conversion of benzene oxide to oxepin; such "unzipping" of graphene and CO2 desorption is favored at oxygen-saturated edges, thus accounting for the well-documented phenomenon of induced heterogeneity of carbon reactive sites.
引用
收藏
页码:17166 / 17175
页数:10
相关论文
共 59 条
[1]   OPENING CARBON NANOTUBES WITH OXYGEN AND IMPLICATIONS FOR FILLING [J].
AJAYAN, PM ;
EBBESEN, TW ;
ICHIHASHI, T ;
IIJIMA, S ;
TANIGAKI, K ;
HIURA, H .
NATURE, 1993, 362 (6420) :522-525
[2]  
[Anonymous], REACTIVE INTERMEDIAT
[3]   Rational chemical strategies for carbon nanotube functionalization [J].
Banerjee, S ;
Kahn, MGC ;
Wong, SS .
CHEMISTRY-A EUROPEAN JOURNAL, 2003, 9 (09) :1899-1908
[4]   Computational study of the mechanisms for the reaction of O2(3Σg) with aromatic radicals [J].
Barckholtz, C ;
Fadden, MJ ;
Hadad, CM .
JOURNAL OF PHYSICAL CHEMISTRY A, 1999, 103 (40) :8108-8117
[5]   QUANTUM CHEMICAL STUDY OF OXYGEN-ADSORPTION ON GRAPHITE .1. MOLECULAR-ORBITAL STUDY OF ADSORPTION AND MIGRATION OF MOLECULAR-OXYGEN ON GRAPHITE [J].
BERAN, S ;
DUBSKY, J ;
SLANINA, Z .
SURFACE SCIENCE, 1979, 79 (01) :39-52
[6]   SOME ASPECTS OF THE SURFACE-CHEMISTRY OF CARBON-BLACKS AND OTHER CARBONS [J].
BOEHM, HP .
CARBON, 1994, 32 (05) :759-769
[7]   Modeling of graphite oxide [J].
Boukhvalov, D. W. ;
Katsnelson, M. I. .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2008, 130 (32) :10697-10701
[8]   Chemical functionalization of graphene [J].
Boukhvalov, D. W. ;
Katsnelson, M. I. .
JOURNAL OF PHYSICS-CONDENSED MATTER, 2009, 21 (34)
[9]   Oxidation of carbon nanotubes by singlet O2 -: art. no. 086403 [J].
Chan, SP ;
Chen, G ;
Gong, XG ;
Liu, ZF .
PHYSICAL REVIEW LETTERS, 2003, 90 (08) :4
[10]   A NEW SURFACE OXYGEN COMPLEX ON CARBON - TOWARD A UNIFIED MECHANISM FOR CARBON GASIFICATION REACTIONS [J].
CHEN, SG ;
YANG, RT ;
KAPTEIJN, F ;
MOULIJN, JA .
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 1993, 32 (11) :2835-2840