Bilayer SnO2–WO3 nanofilms for enhanced NH3 gas sensing performance

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2017-10, Vol.224, p.163-170
• Main Authors: Toan, Nguyen Van, Hung, Chu Manh, Duy, Nguyen Van, Hoa, Nguyen Duc, Le, Dang Thi Thanh, Hieu, Nguyen Van
• Format: Article
• Language: English
• Subjects: Ammonia; Bilayers; Catalysis; Chemical synthesis; Gas sensors; Nanofilms; NH3 gas sensor; Reactive sputtering; Selectivity; SnO2; Thin films; Tin dioxide; Tungsten oxides; WO3
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2017.08.004

[Display omitted] •The loading WO3 nanofilm results in an enhanced NH3 response of SnO2 film sensors.•Bilayer SnO2–WO3 sensors is advantageous over bare SnO2 and WO3 nanofilm sensors.•The catalyst effect of WO3 nanofilm on NH3 gas molecules is main contribution.•The mass-fabrication of miniaturized and cost-effective NH3 sensors can be developed from the present work. Bilayer SnO2–WO3 nanofilm sensors with high sensitivity and selectivity for NH3 gas were developed. The sensitized WO3 nanofilms (5–15nm) were deposited on the top of SnO2 nanofilms without vacuum break via reactive sputtering. The SnO2 nanofilm sensitized with 10-nm-thick WO3 nanofilm exhibited the best performance for sensing NH3 gas. The gas response (Ra/Rg) value of SnO2–WO3 nanofilm sensor to 250ppm NH3 was as high as 7.1 at 300°C and increased by approximately threefold compared with that of the bare SnO2 nanofilm sensor. At 300°C, the cross-gas responses of the SnO2–WO3 nanofilm sensor to 250ppm H2 (Ra/Rg=1.5) and C2H5OH (Ra/Rg=1.4) were negligibly low. The catalytic effect of WO3 nanofilm on NH3 gas molecules mainly enhanced the NH3-gas-sensing performance of the SnO2 nanofilm sensor. This work proposes an effective platform for the mass-fabrication of miniaturized, cost-effective, and highly sensitive NH3 gas sensors.