TY - JOUR
T1 - CO Oxidation Prefers the Eley-Rideal or Langmuir-Hinshelwood Pathway
T2 - Monolayer vs Thin Film of SiC
AU - Sinthika, S.
AU - Vala, Surya Teja
AU - Kawazoe, Y.
AU - Thapa, Ranjit
N1 - Funding Information:
R.T. and S.S. thank the Science and Engineering Research Board (SERB) of India for the financial support (Grant no. SB/FTP/PS028/2013). The authors thank SRM Research Institute of SRM University for providing the supercomputing facility and financial support. Y.K. thanks the Russian Megagrant Project (No. 14.B25.31.0030) ?New energy technologies and energy carriers? for support.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/3/2
Y1 - 2016/3/2
N2 - Using the first-principles approach, we investigated the electronic and chemical properties of wurtzite silicon carbide (2H-SiC) monolayer and thin film structures and substantiated their catalytic activity toward CO oxidation. 2H-SiC monolayer, being planar, is quite stable and has moderate binding with O2, while CO interacts physically; thus, the Eley-Rideal (ER) mechanism prevails over the Langmuir-Hinshelwood (LH) mechanism with an easily cleared activation barrier. Contrarily, 2H-SiC thin film, which exhibits a nonplanar structure, allows moderate binding of both CO and O2 on its surface, thus favoring the LH mechanism over the ER one. Comprehending these results leads to a better understanding of the reaction mechanisms involving structural contrast. Weak overlapping between the 2pz(C) and 3pz(Si) orbitals of the SiC monolayer system has been found to be the primary reason to revert the active site toward sp3 hybridization, during interaction with the molecules. In addition, the influences of graphite and Ag(111) substrates on the CO oxidation mechanism were also studied, and it is observed that the ER mechanism is preserved on SiC/G system, while CO oxidation on the SiC/Ag(111) system follows the LH mechanism. The calculated Sabatier activities of the SiC catalysts show that the catalysts are very efficient in catalyzing CO oxidation.
AB - Using the first-principles approach, we investigated the electronic and chemical properties of wurtzite silicon carbide (2H-SiC) monolayer and thin film structures and substantiated their catalytic activity toward CO oxidation. 2H-SiC monolayer, being planar, is quite stable and has moderate binding with O2, while CO interacts physically; thus, the Eley-Rideal (ER) mechanism prevails over the Langmuir-Hinshelwood (LH) mechanism with an easily cleared activation barrier. Contrarily, 2H-SiC thin film, which exhibits a nonplanar structure, allows moderate binding of both CO and O2 on its surface, thus favoring the LH mechanism over the ER one. Comprehending these results leads to a better understanding of the reaction mechanisms involving structural contrast. Weak overlapping between the 2pz(C) and 3pz(Si) orbitals of the SiC monolayer system has been found to be the primary reason to revert the active site toward sp3 hybridization, during interaction with the molecules. In addition, the influences of graphite and Ag(111) substrates on the CO oxidation mechanism were also studied, and it is observed that the ER mechanism is preserved on SiC/G system, while CO oxidation on the SiC/Ag(111) system follows the LH mechanism. The calculated Sabatier activities of the SiC catalysts show that the catalysts are very efficient in catalyzing CO oxidation.
KW - adsorption
KW - density functional theory
KW - electronic structure
KW - interface
KW - oxidation
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U2 - 10.1021/acsami.5b11384
DO - 10.1021/acsami.5b11384
M3 - Article
AN - SCOPUS:84959562562
VL - 8
SP - 5290
EP - 5299
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 8
ER -