Highly sensitive and selective trimethylamine sensors using Ru-doped SnO2 hollow spheres

Abstract The 0.45 mol% Ru-doped SnO 2 (Ru–SnO 2 ) hollow spheres, each with a shell thickness of ∼17 nm, were prepared by the uniform coating of Ru- and Sn-precursors onto SiO 2 microspheres with diameters of ∼300 nm, followed by heat treatment at 350 °C and subsequent removal of the core SiO 2 using a dilute HF solution. The Ru–SnO 2 hollow spheres showed high responses to 5 ppm trimethylamine (TMA) at 350 °C with negligible cross-responses to toluene, benzene, NH 3 , CO, H 2 , and C 3 H 8 and decreased cross-responses to C 2 H 5 OH, while undoped SnO 2 hollow spheres showed similar responses to TMA and C 2 H 5 OH. The selective and sensitive detection of TMA that was achieved in Ru-doped SnO 2 hollow spheres is explained in relation to the catalytic sensitization of Ru and the gas-accessible hollow morphology of the thin shell configurations.