CO-sensing properties of a NASICON-based gas sensor attached with Pt mixed with Bi2O3 as a sensing electrodeby Hirotaka Takeda, Taro Ueda, Kai Kamada, Katsuhide Matsuo, Takeo Hyodo, Yasuhiro Shimizu

Electrochimica Acta


Electrochemistry / Chemical Engineering (all)


Morphological relaxation of glass surfaces

G. DE With, A. J. Corbijn

Progress in NASICON-based mixed-potential type gas sensors

Xishuang Liang, Biao Wang, Han Zhang, Quan Diao, Baofu Quan, Geyu Lu

High Temperature Mixed-potential-type Ammonia Sensor Using Stabilized Zirconia and Oxide-based Sensing Electrode

Perumal Elumalai, Vladimir Plashnitsa, Yuki Fujio, Norio Miura


d 1, as op h

Electrochimica Acta 155 (2015) 8–15

Contents lists available at ScienceDirect

Electrochim journal homepa ge: www.elseAccepted 30 December 2014

Available online 3 January 2015

Keywords: gas sensor carbon monoxide solid electrolyte

NASICON amount of Bi2O3 addition (wt%)) and Pt as a reference electrode were fabricated, and their sensing properties to CO and H2 were examined in the operating temperature range of 25300 C in dry and wet air. The sensors obtained were denoted as Pt(nBi2O3)/Pt. All Pt(nBi2O3)/Pt sensors fabricated responded to

CO at all operating temperatures tested, and the magnitude of CO response increased with a decrease in the operating temperature. In addition, the magnitude of CO response largely depended on the additive amounts of Bi2O3 to the Pt sensing electrode. The increase in the additive amount of Bi2O3 to the Pt sensing electrode (0.01  n  1) enhanced markedly the magnitude of CO response, 90% response time and CO selectivity against H2. The Pt(1Bi2O3)/Pt sensor showed a linear relationship between the CO response and the logarithm of CO concentration (13000 ppm) in dry air at 25 C and the CO selectivity against H2 was enhanced in wet air, in comparison with those observed in dry air. The interfacial layer, which was formed between the NASICON and the Pt(1Bi2O3) electrode, was suggested to play an important role in improving of the CO-sensing properties. ã 2015 Elsevier Ltd. All rights reserved. 1. Introduction

Various types of gas sensors (e.g., semiconductor type [1,2], diode type [3–5], catalytic-combustion type [6] and solidelectrolyte type [7–23]) have been widely investigated and developed to detect various gases such as volatile organic compounds (VOCs) [7,8], carbon monoxide (CO) [1,2,6,9,10] and hydrogen (H2) [5,11,12] under different atmospheres. They have contributed to forestall various serious troubles to human beings, such as sick building syndrome (for VOC), difficulty of breathing (for CO) and explosion accidents (for H2). Among them, the solidelectrolyte gas sensors have advantages, since they can detect some kinds of gases selectively and sensitively, by optimization of the composition and microstructure of the gas-sensing electrodes as well as the electrolyte. NASICON (Na3Zr2Si2PO12) is well-known as a promising electrolyte which shows relatively high ionic conductivity at low temperatures (e.g., 5.2  102 S m1 at RT [24]), and thus many efforts have recently directed to developing the

NASICON-based gas sensors which can detect various gases, such as SO2 [13], CO2 [14–16], NO2 [17,18], VOCs, [8], NH3 [19] and Cl2 [20]. For example, Obata et al. have demonstrated that a NASICONbased gas sensor using NaNO2-Li2CO3mixed with ITO powders as a sensing electrode material showed stable response to NO2 without interference of humidity even at RT and the response to NO2 was proportional to the logarithm of NO2 concentration [18]. Kida et al. reported that a NASICON-based gas sensor using Bi2Cu0.1V0.9O5.35 as an electrode material could detect VOCs such as ethanol, formaldehyde and toluene [8]. Lu et al. have reported that a

NASICON-based gas sensor using Cr2O3 as a sensing-electrode material showed the high sensitivity to Cl2 at 300 C [20]. We have also reported that the compositional and morphological optimizations of the Li2CO3-BaCO3 auxiliary layer coated onto the sensing electrode of NASICON-based gas sensors were quite effective in improving the CO2 sensitivity [15,16]. As described above, different

NASICON-based sensors have been already investigated for the detection of various gases, but little effort has been directed to developing NASICON-based CO gas sensors. CO is colorless, odorless and badly hazardous to human health, and especially it exerts a negative impact on the respiratory system due to its strong associativity with hemoglobin in the blood [25]. Namely, even the * Corresponding author. Tel.: +81 95 819 2642; fax: +81 95 819 2643.

E-mail address: (Y. Shimizu). 0013-4686/ã 2015 Elsevier Ltd. All rights reserved.CO-sensing properties of a NASICON-base mixed with Bi2O3 as a sensing electrode

Hirotaka Takeda, Taro Ueda, Kai Kamada, Katsuhide

Yasuhiro Shimizu *

Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-852


Article history:

Received 9 October 2014

Received in revised form 23 December 2014


NASICON (Na3Zr2Si2PO12)-b on) have so far been devel

NASICON disc attached wit gas sensor attached with Pt

Matsuo, Takeo Hyodo,

Japan ed gas sensors capable of detecting various gases (CO2, NO2, Cl2, VOC and so ed by many researchers. In this study, planar-type gas sensors using a

Pt mixed with Bi2O3 as a sensing electrode (Pt(nBi2O3), n (0.0130): the ica Acta v ier .com/locate /e lectacta small amount of CO (500 ppm) causes various symptoms such as (NO3)35H2O was fully dissolved in 1.12 M HNO3 aqueous solution, polyvinyl pyrrolidone was added to the solution as a stabilizing agent and then they were stirred for 15 min. The resultant solution was slowly and continuously dropped into 0.2 M NaOH solution under constant stirring, until the pH reached 11. After further stirring for 5 min, the resultant suspension was sonicated at 28 kHz for 30 min. The precipitate was centrifuged and washed with pure water for several times. The resultant product was dried at 80 C for 2 h and then annealed at 500 C for 2 h.

Crystal structure of these materials synthesized was analyzed by X-ray diffraction (XRD, RINT2100; Rigaku Corp.) with CuKa radiation. And their crystallite size was calculated from Scherrer equation. Specific surface area of the Bi2O3 powder was measured by Brunauer–Emmett–Teller (BET) method using a N2 adsorption isotherm (Micromeritics Instruments Corp., Tristar3000), and its microstructure was observed by scanning electron microscopy (SEM; JEOL Ltd. JSM-7500F).

Fig. 1. Schematic structure of a NASICON-based planar gas sensor.