title: Co3O4-SnO2 Hollow Heteronanostructures: Facile Control of Gas Selectivity by Compositional Tuning of Sensing Materials via Galvanic Replacement.
abstract: Co3O4 hollow spheres prepared by ultrasonic spray pyrolysis were converted into Co3O4-SnO2 core-shell hollow spheres by galvanic replacement with subsequent calcination at 450 °C for 2 h for gas sensor applications. Gas selectivity of the obtained spheres can be controlled by varying the amount of SnO2 shells (14.6, 24.3, and 43.3 at. %) and sensor temperatures. Co3O4 sensors possess an ability to selectively detect ethanol at 275 °C. When the amount of SnO2 shells was increased to 14.6 and 24.3 at. %, highly selective detection of xylene and methylbenzenes (xylene + toluene) was achieved at 275 and 300 °C, respectively. Good selectivity of Co3O4 hollow spheres to ethanol can be explained by a catalytic activity of Co3O4; whereas high selectivity of Co3O4-SnO2 core-shell hollow spheres to methylbenzenes is attributed to a synergistic effect of catalytic SnO2 and Co3O4 and promotion of gas sensing reactions by a pore-size control of microreactors.
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Hyun-Mook
authors.initials: HM
authors.lastname: Jeong
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Jae-Hyeok
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Seong-Yong
authors.initials: SY
authors.lastname: Jeong
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Chang-Hoon
authors.initials: CH
authors.lastname: Kwak
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Jong-Heun
authors.initials: JH
authors.lastname: Lee
keywords: Co3O4; SnO2; galvanic replacement; gas sensor; heterostructure; methylbenzene