title: Highly sensitive room-temperature surface acoustic wave (SAW) ammonia sensors based on Co₃O₄/SiO₂ composite films.
abstract: Surface acoustic wave (SAW) sensors based on Co3O4/SiO2 composite sensing films for ammonia detection were investigated at room temperature. The Co3O4/SiO2 composite films were deposited onto ST-cut quartz SAW resonators by a sol-gel method. SEM and AFM characterizations showed that the films had porous structures. The existence of SiO2 was found to enhance the ammonia sensing property of the sensor significantly. The sensor based on a Co3O4/SiO2 composite film, with 50% Co3O4 loading, which had the highest RMS value (3.72), showed the best sensing property. It exhibited a positive frequency shift of 3500 Hz to 1 ppm ammonia as well as excellent selectivity, stability and reproducibility at room temperature. Moreover, a 37% decrease in the conductance of the composite film as well as a positive frequency shift of 12,500 Hz were observed when the sensor was exposed to 20 ppm ammonia, indicating the positive frequency shift was derived from the decrease in film conductance.
authors.affiliation: School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Yong-Liang
authors.initials: YL
authors.lastname: Tang
authors.affiliation: School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Zhi-Jie
authors.initials: ZJ
authors.lastname: Li
authors.affiliation: Sichuan Institute of Piezoelectric and Acousto-optic Technology, Chongqing 400060, PR China.
authors.forename: Jin-Yi
authors.initials: JY
authors.lastname: Ma
authors.affiliation: Advanced Materials Research Institute, University of New Orleans, LA 70148, United States.
authors.forename: Hai-Qiao
authors.initials: HQ
authors.lastname: Su
authors.affiliation: School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Yuan-Jun
authors.initials: YJ
authors.lastname: Guo
authors.affiliation: Sichuan Institute of Piezoelectric and Acousto-optic Technology, Chongqing 400060, PR China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Sichuan Institute of Piezoelectric and Acousto-optic Technology, Chongqing 400060, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Du
authors.affiliation: Advanced Materials Research Institute, University of New Orleans, LA 70148, United States.
authors.forename: Jia-Jun
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Advanced Materials Research Institute, University of New Orleans, LA 70148, United States.
authors.forename: Weilie
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Ingram School of Engineering, and MSEC, Texas State University, San Marcos, TX 78666, United States.
authors.forename: Qing-Kai
authors.initials: QK
authors.lastname: Yu
authors.affiliation: School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, PR China; Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, PR China. Electronic address: xtzu@uestc.edu.cn.
authors.forename: Xiao-Tao
authors.initials: XT
authors.lastname: Zu
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000032:analysis*; D003035:Cobalt / Q000737:chemistry*; D004784:Environmental Monitoring / Q000295:instrumentation*; D010087:Oxides / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D010087:Oxides; D003035:Cobalt; D012822:Silicon Dioxide; D000641:Ammonia; C060728:cobalt oxide
keywords: Ammonia; Co(3)O(4); Composite film; SAW sensor; SiO(2)