Highly selective and sensitive CH4 gas sensors based on flame-spray-made Cr-doped SnO2 particulate films

• Published in: Sensors and actuators. B, Chemical Chemical, 2019-07, Vol.291, p.177-191
• Main Authors: Bunpang, K., Wisitsoraat, A., Tuantranont, A., Singkammo, S., Phanichphant, S., Liewhiran, C.
• Format: Article
• Language: English
• Subjects: Ammonia; CH4 gas sensor; Chromium; Cr doping; Flame spray pyrolysis; Flammability; Flammable gases; Gas sensors; Methane; Nanoparticles; Nitrogen dioxide; Optimization; Photoelectrons; Response time; Scanning electron microscopy; Selectivity; SnO2 nanoparticles; Solid solutions; Spin coating; Substitutional solid solutions; Tin dioxide; Transmission electron microscopy; X-ray diffraction
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2019.04.049

[Display omitted] •Flame-made SnO2 nanoparticles (5–20 nm) were incorporated with 0–2 wt% Cr.•Structural analyses suggested Cr atoms were substitutionally doped in SnO2 lattice.•Response to 1 vol% CH4 at 350 °C was greatly improved from 8.9 to 1268 with 0.5 wt% Cr.•The optimal sensor exhibited high CH4 selectivity against H2, C2H2, NO2, NO, N2O, CO, NH3, SO2, C2H5OH, C3H6O and H2O.•Cr dopants catalytically enhanced the dissociation and oxidation of CH4. In this research, flame-spray-made 0–2 wt% Cr-doped SnO2 nanoparticles were synthesized and methodically studied for specific detection of methane (CH4) for the first time. From characterizations using X-ray diffraction, X-ray photoelectron spectroscopy, scanning/transmission electron microscopy and nitrogen adsorption, Cr was found to form substitutional solid solution in 5–20 nm nanoparticles with tetragonal SnO2 structure. In addition, grain and particle sizes decreased while surface area increases considerably with increasing Cr content. The sensing films prepared by spin coating technique were evaluated towards various flammable and toxic gases in dry air at 200–400 °C. Gas–sensing data evidently showed that the SnO2layer with the optimum Cr-doping level of 0.5 wt% offered a remarkable response of ˜1268 with a decent response time of ˜3.9 s to 1 vol% CH4at the optimum working temperature of 350 °C. In addition, the optimal Cr-doped SnO2sensor gave high CH4 selectivity against H2, C2H2, NO2, NO, N2O, CO, NH3, SO2, C2H5OH, C3H6O and H2O. Therefore, the flame-spray-made Cr-doped SnO2material is an attractive choice for selective and sensitive detection of CH4.