title: Understanding complete oxidation of methane on spinel oxides at a molecular level.
abstract: It is crucial to develop a catalyst made of earth-abundant elements highly active for a complete oxidation of methane at a relatively low temperature. NiCo2O4 consisting of earth-abundant elements which can completely oxidize methane in the temperature range of 350-550 °C. Being a cost-effective catalyst, NiCo2O4 exhibits activity higher than precious-metal-based catalysts. Here we report that the higher catalytic activity at the relatively low temperature results from the integration of nickel cations, cobalt cations and surface lattice oxygen atoms/oxygen vacancies at the atomic scale. In situ studies of complete oxidation of methane on NiCo2O4 and theoretical simulations show that methane dissociates to methyl on nickel cations and then couple with surface lattice oxygen atoms to form -CH3O with a following dehydrogenation to -CH2O; a following oxidative dehydrogenation forms CHO; CHO is transformed to product molecules through two different sub-pathways including dehydrogenation of OCHO and CO oxidation.
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Franklin Feng
authors.initials: FF
authors.lastname: Tao
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Jun-Jun
authors.initials: JJ
authors.lastname: Shan
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Luan
authors.initials: L
authors.lastname: Nguyen
authors.affiliation: School of Chemistry and Chemical Engineering, Queens University, Belfast BT9 5AG, UK.
authors.forename: Ziyun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Shiran
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Center for Nanophase Materials Sciences and Chemical Science Division, Oak Ridge National Laboratory Oak Ridge, Tennessee 37831, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Center for Nanophase Materials Sciences and Chemical Science Division, Oak Ridge National Laboratory Oak Ridge, Tennessee 37831, USA.
authors.forename: Zili
authors.initials: Z
authors.lastname: Wu
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Weixin
authors.initials: W
authors.lastname: Huang
authors.affiliation: 1] Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, USA. [2] Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Shibi
authors.initials: S
authors.lastname: Zeng
authors.affiliation: School of Chemistry and Chemical Engineering, Queens University, Belfast BT9 5AG, UK.
authors.forename: P
authors.initials: P
authors.lastname: Hu