title: Photocatalytic oxidation of methane over SrCO3decorated SrTiO3nanocatalysts via a synergistic effect.
abstract: Because of the high C-H bond energy as well as the non-polar feature of CH4molecules, oxidation of methane under mild conditions remains a challenging task for both C1 utilization and atmospheric environmental cleansing. Here we report that by using a sol-gel method SrCO3decorated SrTiO3nanocatalysts (SrTiO3-S) with an average particle size of ∼25 nm can be readily prepared, which surprisingly show efficient performance for photocatalytic oxidation of methane with the activity close to fourfold of P25, a benchmark photocatalyst. Further investigation revealed a synergistic effect between SrCO3and SrTiO3when combined together into a composite material as both of which are totally inactive for methane oxidation if used alone. Gas adsorption characterization disclosed that the SrCO3can adsorb methane and cannot adsorb carbon dioxide, whereas the SrTiO3will preferentially adsorb CO2instead of CH4. Photocurrent and photoluminescence measurements indicate that SrCO3exhibits a negligible photocurrent response relative to the SrTiO3semiconductor under simulated solar light illumination but the formation of the SrCO3/SrTiO3junction structure (SrTiO3-S) helps reduce surface recombination of the photogenerated electrons and holes. All these results refer to the synergistic mechanism in which the SrCO3acts as a trapping agent to adsorb methane and weaken its C-H bond while the SrTiO3acts as a photocatalyst to activate and oxidize methane under light illumination. The underlying photooxidation mechanism is further investigated with the aid of in situ electron paramagnetic resonance and infrared spectroscopy.
authors.affiliation: Key Laboratory of Design and Assembly of Functional Nanostructures & Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China. zhiguo@fjirsm.ac.cn.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Pan
authors.affiliation: Key Laboratory of Design and Assembly of Functional Nanostructures & Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China. zhiguo@fjirsm.ac.cn and Institute of Nanoscience and Nanotechnology, Department of Physics, Central China Normal University, Wuhan 430079, China.
authors.forename: Xuxing
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Design and Assembly of Functional Nanostructures & Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China. zhiguo@fjirsm.ac.cn.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yi