Co3O4–SnO2 Hollow Heteronanostructures: Facile Control of Gas Selectivity by Compositional Tuning of Sensing Materials via Galvanic Replacement

• Published in: ACS applied materials & interfaces Vol. 8; no. 12; pp. 7877 - 7883
• Main Authors: Jeong, Hyun-Mook, Kim, Jae-Hyeok, Jeong, Seong-Yong, Kwak, Chang-Hoon, Lee, Jong-Heun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 30.03.2016
• Subjects: gas sensor; SnO2; galvanic replacement; heterostructure; methylbenzene; Co3O4
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.6b00216

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.