title: Improvement of H2S sensing properties of SnO2-based thick film gas sensors promoted with MoO3 and NiO.
abstract: The effects of the SnO2 pore size and metal oxide promoters on the sensing properties of SnO2-based thick film gas sensors were investigated to improve the detection of very low H2S concentrations (<1 ppm). SnO2 sensors and SnO2-based thick-film gas sensors promoted with NiO, ZnO, MoO3, CuO or Fe2O3 were prepared, and their sensing properties were examined in a flow system. The SnO2 materials were prepared by calcining SnO2 at 600, 800, 1,000 and 1,200 °C to give materials identified as SnO2(600), SnO2(800), SnO2(1000), and SnO2(1200), respectively. The Sn(12)Mo5Ni3 sensor, which was prepared by physically mixing 5 wt% MoO3 (Mo5), 3 wt% NiO (Ni3) and SnO2(1200) with a large pore size of 312 nm, exhibited a high sensor response of approximately 75% for the detection of 1 ppm H2S at 350 °C with excellent recovery properties. Unlike the SnO2 sensors, its response was maintained during multiple cycles without deactivation. This was attributed to the promoter effect of MoO3. In particular, the Sn(12)Mo5Ni3 sensor developed in this study showed twice the response of the Sn(6)Mo5Ni3 sensor, which was prepared by SnO2(600) with the smaller pore size than SnO2(1200). The excellent sensor response and recovery properties of Sn(12)Mo5Ni3 are believed to be due to the combined promoter effects of MoO3 and NiO and the diffusion effect of H2S as a result of the large pore size of SnO2.
authors.affiliation: Department of Chemical Engineering, Kyungpook National University, Daegu 702-701, Korea. soochool@knu.ac.kr
authors.forename: Soo Chool
authors.initials: SC
authors.lastname: Lee
authors.forename: Seong Yeol
authors.initials: SY
authors.lastname: Kim
authors.forename: Byung Wook
authors.initials: BW
authors.lastname: Hwang
authors.forename: Suk Yong
authors.initials: SY
authors.lastname: Jung
authors.forename: Dhanusuraman
authors.initials: D
authors.lastname: Ragupathy
authors.forename: In Sung
authors.initials: IS
authors.lastname: Son
authors.forename: Duk Dong
authors.initials: DD
authors.lastname: Lee
authors.forename: Jae Chang
authors.initials: JC
authors.lastname: Kim
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry; D005740:Gases / Q000302:isolation & purification; D006862:Hydrogen Sulfide / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D008982:Molybdenum / Q000737:chemistry; D036103:Nanotechnology; D009532:Nickel / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D014001:Tin / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D005740:Gases; D010087:Oxides; C082290:molybdenum trioxide; D014001:Tin; D009532:Nickel; D008982:Molybdenum; C028007:nickel monoxide; D015034:Zinc Oxide; D006862:Hydrogen Sulfide