Sensors and Actuators B 148 (2010) 292–297
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A novel cataluminescence gas sensor based on MgO thin ﬁlm Ying Tao, Xiaoan Cao ∗ , Yan Peng, Yonghui Liu Environmental Science and Engineering Institute, Guangzhou University, No. 230 Wai-Huan West Road, 510006 Guangzhou, PR China
a r t i c l e
i n f o
Article history: Received 17 February 2010 Received in revised form 21 April 2010 Accepted 28 April 2010 Available online 5 May 2010 Keywords: 2-Methoxyethanol 2-Ethoxyethanol MgO ﬁlm Chemiluminescence Gas sensor
a b s t r a c t Using MgO ﬁlm as sensing material, a cataluminescence sensor was proposed by the determination of ethylene glycol ethers (2-ethoxyethanol and 2-methoxyethanol). This ethylene glycol ethers sensor showed high sensitivity and speciﬁcity. With detection limits of 1.0 ppm and 1.4 ppm, the linear ranges of cataluminescence intensity versus ethylene glycol ethers concentrations were 2.0–2000 ppm for 2ethoxyethanol and 2.0–1500 ppm for 2-methoxyethanol, respectively. The response time was less than 5 s. Foreign substances passed through the surface of MgO ﬁlm without response, such as ammonia, benzene, ethyl acetate, acetaldehyde, vinyl acetate, methanol, acetone, ethanol, acetic acid, formaldehyde, and isopropyl ether. The sensor could determine 2-ethoxyethanol and 2-methoxyethanol whether they existed alone or together in air samples. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Ethylene glycol ethers are frequently used as solvents, detergents, and emulsiﬁers alone or as components in numerous industrial and domestic products such as paints, varnishes, inks, cosmetics, and cleaning agents industrial. There exist extensive literatures reporting reproductive, testicular, embryotoxic, teratogenic and hematologic toxicity of ethylene glycol ethers in animal experiments [1–3]. In the 1990s ethylene glycol ethers were reported be responsible for a higher risk level of miscarriage amongst women workers in semiconductor factories in USA [4,5]. 2-Methoxyethanol (EM, CAS No. 109-86-4) and 2ethoxyethanol (EE, CAS No. 110-80-5) are two typical members of industrial solvents collectively known as ethylene glycol ethers. They are mainly used as solvents, colorant, and stabilizer in dyes industry. The standard permitted concentrations of EM and EE vapors in ambient air are less than 8.8 ppm and 8.9 ppm ruled by the Occupational Exposure Limit for hazardous agents in the workplace (GBZ 2-2002, China). Short-chained ethylene glycol ethers are phased out due to their health hazards, EE has been forbidden in Germany. However, EM and EE are still widely used in most of other countries [6,7]. The ethylene glycol ethers may readily enter the body by inhalation as well as dermal uptake. A rapid detecting technique of EM or EE is very important in modern industry.
∗ Corresponding author. Tel.: +86 20 39366937; fax: +86 20 39366946. E-mail address: [email protected]
(X. Cao). 0925-4005/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2010.04.043
Primary methods determined EM and EE are based on biological monitoring , gas chromatograph equipped with ﬂame ionization detector (GC-FID) [9,10], gas chromatography–mass spectrometry (GC/MS) , and UV/vis spectrometer . They possessed high performance and sensitivity, however, with difﬁcult operation and no real-time detection. Gas sensors have advantages of on-site and real-time detection of hazard vapors. There is no speciﬁc sensor for detection of EM and EE. So, ethylene glycol ethers sensor was developed to detect gaseous quickly in workplace. In 1976, Breysse et al. observed that a weak catalytic luminescence phenomenon occurred during catalytic oxidation of CO on ThO2 surface . This chemiluminescence mode was deﬁned as cataluminescence (CTL). In the 1990s, Nakagawa et al. reported CTL sensors using ␥-Al2 O3 as catalyst material for determination of ethanol and acetone [14–18]. Zhang et al. developed the CTL sensors, a porous alumina ﬁlm with 0.5 mm thick was used for detecting saccharides . Many nano-materials such as TiO2 , ZrO2 , BaCO3 , SrCO3 , ZnO, ␥-Al2 O3 , La2 O3 , ␥-Al2 O3 + Nd2 O3 , V2 Ti4 O13 , and Y2 O3 were applied to detect organic vapors of ethanol, acetaldehyde, pinacolyl alcohol, propane, butane, acetone, ethylene dichloride, benzaldehyde, ethyl ether, and acetic acid with high sensitivity and speciﬁcity [20–33]. Cao reported that the vinyl acetate sensor based on MgO nanoparticles showed good cataluminescence characters . New development of CTL array sensors can distinguish several different gases . CTL gas sensors have advantages of on-site and real-time detection, small size, and no need of lamp-house. Nevertheless, it is still a challenge for scientists to obtain better sensitive and speciﬁc CTL sensors to some toxic gases since their low level of concentrations in the air.
Y. Tao et al. / Sensors and Actuators B 148 (2010) 292–297
Fig. 1. Schematic diagram of the CTL detection system.
In chemistry sensors, ﬁlm catalysts were used to improve stability, sensitivity and speciﬁcity. ZnO and SnO2 thin ﬁlm sensors were reported to enhance the sensitivity of CO and NO2 [36,37]. MgO is a widely used catalysis, its thin ﬁlm has also been considered as a suitable material for technological applications. It can be used as sensor elements for humidity sensor  and CH3 OH adsorption . However, there are few thin ﬁlms used in the cataluminescence sensors. Most of nano-materials in cataluminescence sensors are in powder state and might easily come off the substrates. Since thin ﬁlms could attach ﬁrmly and uniformly to the substrate, MgO thin ﬁlm was synthesized and characterized in the present study. A new CTL-based gas sensor using MgO thin ﬁlm for the detection of ethylene glycol ethers vapors was developed. MgO thin ﬁlm exhibited the highest sensitivity of EE and EM and showed good analytical characters. To the best of our knowledge, EE and EM sensors have been reported in the present work ﬁrstly. 2. Materials and methods 2.1. Apparatus The schematic diagram of the detection system was shown in Fig. 1. The catalyst was coated as a layer on the ceramic heating tubes which were coated with nano-size gold. The 5 mm in diameter ceramic heating tube was put into a 12 mm inner-diameter quartz tube. The temperature of the catalysts could be adjusted by controlling the voltage of the heating tube. The air from the pump was mixed with detecting vapor and ﬂowed through the quartz tube, a catalytic reaction occurred on the surface of catalysts. The CTL intensity was measured by a BPCL Ultra Weak Chemiluminescence Analyzer (Biophysics Institute of Chinese Academy of Science, PR China). 2.2. Synthesis and characterization of thin ﬁlm materials All regents were of analytical grade. Indium chloride (InCl3 ·4H2 O) was obtained from Reagent No. 1 Factory of Shanghai Chemical Reagent Co., Ltd. Magnesium chloride (MgCl2 ·6H2 O), sodium citrate (Na3 C6 H5 O7 ·2H2 O), polyethylene glycol (PEG6000), zirconium nitrate (Zr(NO3 )4 ·3H2 O), and oxalic acid were purchased from Tianjin Damao Chemical regent Factory. In2 O3 , MgO and ZrO2 were prepared by sol–gel method. (1) In2 O3 precursor was synthesized as follows: 0.65 g InCl3 ·4H2 O and 1.0 g PEG-2000 were dissolved in 30 mL distilled water with vigorous stirring for 30 min. Then 10% ammonia solution was added until a white precipitate of In(OH)3 was formed, further addition of ammonia solution resulted in dissolving of the precipitate until
Fig. 2. TFE-SEM photo of MgO thin ﬁlm.
pH value reached 5. Then stirred for another 1 h. (2) MgO precursor was synthesized as follows: 2.5 g MgCl2 ·6H2 O and 2.5 g PEG-6000 were dissolved in 50 mL distilled water with vigorous stirring for 20 min, NaOH solution was added into the mixture until pH value reached 12. Keep on stirring for 1 h. (3) ZrO2 precursor was synthesized as the above method, the molar ratio of zirconium nitrate to oxalic acid was 4.5:1. Fabrication of the thin ﬁlms: Ceramic heating tubes which were coated with gold were used as the solid substrate for ﬁlm growth. The substrates were washed with hydrochloric acid, ethanol, and distilled water in sequence and dried in oven at last. Thin ﬁlm systems were prepared by using the dip coating method from each colloidal and sol–gel solution. MgO thin ﬁlms were synthesized in the following way: The ceramic substrates were immersed into the MgO precursor solution for ﬁve times, dried at 80 ◦ C for 1 h and decomposed to MgO when calcined at 450 ◦ C for 1 h. Other ﬁlms such as In2 O3 and ZrO2 were synthesized following the same method. MgO ﬁlm produced in the present work was characterized for its surface morphology and chemical composition. The microstructure of the ﬁlm was investigated by Quanta 400 thermal ﬁeld emission environment scanning electron microscope (TFE-SEM). Specimens were observed at accelerating voltages <20 kV. Fig. 2 showed the surface morphology of the ﬁlm. The thickness of the ﬁlm was measured by dektak 150 surface proﬁler (Veeco Instruments Inc.). Subsequently, chemical compositions of the annealed ﬁlms were determined using the X-ray photoelectron spectroscopy (XPS, model: ESCALAB 250; manufacturer: Thermo Fisher Scientiﬁc). XPS analysis was using a Mono Al K␣ (1486.6 eV), X-ray source operating at 150 W. The vacuum of the analysis chamber was better than 2 × 10−9 mbar. All spectra were acquired at a ﬁxed analyzer energy mode. Pass energy of 150 eV was applied to wide scans,
Table 1 Chemical composition of the MgO thin ﬁlm surface. Name
Peak BE (eV)
Atomic percent (%)
C 1s O 1s Mg 1s Cl 2p F 1s Na 1s
284.75 532.52 1305.89 199.71 685.95 1073.97
1.83 2.75 2.92 2.59 2.12 3.98
31.53 44.84 18.36 1.61 0.99 2.66
Y. Tao et al. / Sensors and Actuators B 148 (2010) 292–297
Table 2 Comparison of signal-to-noise ratio of six air pollutions on some materials. Materials
In2 O3 ZrO2 MgO
Signal-to-noise ratio (S/N)
0.73 1.69 64.52
0.63 Not detectable 104.91
0.7 1.19 0.43
0.43 Not detectable 0.55
1.24 1.08 1.06
Not detectable 0.59 Not detectable
296 ◦ C, 425 m 279 ◦ C, 425 m 279 ◦ C, 425 m
while 20 eV was used for narrow region scans. The binding energies were calibrated with reference to C 1s at 284.8 eV for adventitious hydrocarbon contamination. The analysis area was 500 m with a typical analysis depth of 5–10 nm.
3. Results and discussion 3.1. Structure of the thin ﬁlm material The surface morphology of MgO thin ﬁlm was shown in Fig. 2. It could be seen in Fig. 2 that MgO ﬁlm has a plate like structure. The thickness of the ﬁlms depends on the dig time. And the thicknesses of MgO and In2 O3 ﬁlms are 0.23 m and 0.20 m, respectively. XPS analysis was used to detect the element ingredients of MgO ﬁlm. Table 1 summarized the atomic weight ratios of elements and surface chemical compositions of MgO ﬁlm, which were calculated from the experimental data. A single peak of Mg 1s was obtained at 1305 eV, which indicated that the material was MgO. Air pollutions caused high atomic weight ratios of elements C and O.
Fig. 4. Wavelength dependence of CTL intensity of EE and EM vapors. (1) EE: temperature: 279 ◦ C, ﬂow rate: 300 mL/min, and concentration: 500 ppm; (2) EM: temperature: 279 ◦ C, ﬂow rate: 210 mL/min, and concentration: 500 ppm.
3.3. CTL response proﬁle of ethylene glycol ethers on MgO ﬁlm 3.2. Estimation of the thin ﬁlm materials for the sensing mode To select the appropriate sensing materials for ethylene glycol ethers sensor, In2 O3 , ZrO2 , and MgO thin ﬁlms were examined. The CTL responses on the surface of these ﬁlms were detected when all the organic vapors were 500 ppm. All detection conditions in Table 2 were optimal conditions of using each sensing material based on the experiments’ results. The data showed that MgO ﬁlm was the best material to obtain the highest signal-to-noise ratio. It could be attributed to a combination of materials’ differences in (i) diffusivity, (ii) adsorption behavior, and (iii) intrinsic reaction rate (restrictions on the size of the transition state) [40,41]. Therefore, MgO ﬁlm was selected for the subsequent study in the present work. The work on MgO ﬁlm showed that ﬁlm at thickness of 0.2 m was stable, good reproducibility, and will not come off the substrate. So, all the thin ﬁlms were prepared about this thickness.
The CTL response proﬁles of EE and EM on MgO ﬁlm were investigated by injecting each vapor into the carrier gas with certain ﬂow rates. Fig. 3 showed the CTL response proﬁles of samples containing EE or EM at 279 ◦ C with a bandpass ﬁlter of 425 nm. Curves 1 and 2 denoted the results for EE and EM with the same concentration of 500 ppm. The CTL response proﬁles were similar to each other. The peak of each curve appeared at about 5 s after sample injection and the half decay time of each curve was about 45 s, which indicated that the EE and EM sensing were fast processes.
3.4. Optimization of wavelengths In order to investigate the effect of wavelength on the CTL intensity, six bandpass ﬁlters (400, 425, 440, 460, 490, and 535 nm) were used to select the optimal wavelength. The noise signal produced from incandescent radiation of the ceramic heater substrate increased towards longer wavelength, so signal-to-noise ratios were used to show the CTL intensity. From Fig. 4, the optimal wavelength for CTL was 425 nm to detect EE and EM. This wavelength was used for the quantitative analysis because of the lower incandescent radiation.
3.5. Optimization of working temperature
Fig. 3. CTL response proﬁles of EE and EM. (1) EE: temperature: 279 ◦ C, ﬂow rate: 300 mL/min, wavelength: 425 nm, and concentration: 500 ppm; (2) EM: temperature: 279 ◦ C, ﬂow rate: 210 mL/min, wavelength: 425 nm, and concentration: 500 ppm.
The effect of working temperature on CTL was shown in Fig. 5. As shown in Fig. 5, the incandescent radiation noise of substrate increased markedly above 320 ◦ C, therefore 279 ◦ C was selected as the optimum detection temperature owing to the maximum signal-to-noise ratio. Moreover, the noise produced from incandescent radiation was still at a very low level at this temperature. Therefore, 279 ◦ C was used for the subsequent study. The optimum detection temperature of EM was the same as EE’s.
Y. Tao et al. / Sensors and Actuators B 148 (2010) 292–297
Fig. 5. Temperature dependence of CTL intensity of EE and EM vapors. (1) EE: wavelength: 425 nm, ﬂow rate: 300 mL/min, and concentration: 500 ppm; (2) EM: wavelength: 425 nm, ﬂow rate: 210 mL/min, and concentration: 500 ppm.
Fig. 7. CTL responses of different compounds on the sensor. Temperature: 279 ◦ C; wavelength: 425 nm; ﬂow rate: 250 mL/min; and concentration: 500 ppm.
Fig. 6. Effect of ﬂow rate of carrier air on CTL intensity of EE and EM vapors. Temperature: 279 ◦ C; wavelength: 425 nm and concentration: 500 ppm.
linear regression equations of EE and EM were described by I = 7.289C + 2.504 (r = 0.9981) and I = 5.088C − 47.578 (r = 0.9976), respectively. Where I was the relative CTL intensity, C was the concentration of EE or EM (ppm) and r was the regression coefﬁcient. The detection limit was 1.0 ppm for EE and 1.4 for EM. Since the regression equations of EE and EM were a little different, approximate total amounts of ethylene glycol ethers could be obtained if they coexisted in one sample (see sample 1 in Table 3). According to the Occupational Exposure Limit for hazardous agents in the workplace (GBZ 2-2002, China), the maximum allowable concentrations of EE and EM vapor in air are less than 8.9 ppm and 8.8 ppm. The detection limits of the EE and EM vapors are below the standard permitted concentrations, therefore, the sensor can be used for air quality monitoring of ethylene glycol ethers in workplace.
3.6. Optimization of ﬂow rate of carrier gas 3.8. Speciﬁcity of MgO thin ﬁlm gas sensor The ﬂow rate dependence on CTL intensity was investigated ranged from 50 to 395 mL/min. As illustrated in Fig. 6 (EE), the CTL intensity increased gradually with the increase of ﬂow rate from 50 to 300 mL/min. When the ﬂow rate was above 300 mL/min, the CTL intensity deceased slightly. Fig. 6 (EM) showed the similar trend, however, 210 mL/min was the inﬂexion. The results showed that the catalytic oxidation was under a diffusion controlled condition when the ﬂow rate was below 300 mL/min or 210 mL/min. The reason for this case might be that the reaction time between EE, EM and MgO ﬁlm would not be sufﬁcient when ﬂow rates of carrier gas increased to above 300 mL/min or 210 mL/min. So, 300 mL/min and 210 mL/min were ﬁnally chosen for detection.
Eleven kinds of vapors, which might coexist with EE and EM in air, were detected respectively under the optimal conditions. As shown in Fig. 7, vapors of ammonia, benzene, and ethyl acetate had no interference with EE or EM. While, acetaldehyde, vinyl acetate, methanol, acetone, ethanol, acetic acid, formaldehyde, and isopropyl ether caused interferences at levels around 0.77%, 2.01%, 0.87%, 0.66%, 0.40%, 0.61%, 0.48%, and 1.93% compared with the response of EE. Therefore, the sensor was feasibility for the determinations of EE and EM in air owing to signiﬁcantly speciﬁcity to ethylene glycol ethers. 3.9. Lifetime of the sensor
3.7. Analytical characteristics Under the optimal conditions described above, the calibration curves of CTL intensity versus EE or EM concentration were linear in the range of 2.0–2000 ppm or 2.0–1500 ppm. The
The lifetime of the sensor was tested at the optimal conditions. The CTL intensities were measured once per 5 h by continuously introducing 500 ppm of EE for 100 h in the carrier gas through the sensor. No signiﬁcant decrease of CTL intensity was observed dur-
Table 3 Ethylene glycol ethers analysis in artiﬁcial samples. Sample no. 1
Composition EE EM
Prepared values (ppm) 1000 250
Measured values (ppm, n = 6) 1370 ± 87
1080 ± 62
Recovery (%) 110 108
Y. Tao et al. / Sensors and Actuators B 148 (2010) 292–297
ing the 100 h detection. The relative standard deviations were 2.6% (n = 26) for 500 ppm EE, 2.4% (n = 26) for 500 ppm EM. The results indicated the durability of the MgO ﬁlm based sensor. 3.10. Determination of ethylene glycol ethers in the synthetic samples In order to test the feasibility of the sensor, two artiﬁcial samples containing known concentrations of EE and EM, EE and ethanol were analyzed under the optimal conditions. Since EE and EM showed a little different sensitivity, approximate total amounts of EE and EM could be obtained if they coexisted in one sample. As shown in Table 3, the recovery of sample 1 was obtained from the ratio of measured value to aggregate prepared value of EE and EM, while the recovery of sample 2 was obtained from the ratio of measured value to prepared value of EE. Satisfactory recoveries were obtained. As a result of this experiment, EE and EM could be detected separately or when they coexist. 3.11. Mechanism The mechanisms about the oxidation of EE and EM on nanocatalysts have not been studied yet. Lv et al. reported that ethyl ether would oxidized to acetaldehyde and then to acetic acid, during which main luminous intermediates CH3 CO* were generated and emitted light . Therefore, possible mechanisms of the cataluminescence of EM and EE are as the following: For EM :
CH3 OCH2 CH2 OH + O2 −→CH3 OCH2 CHO∗
CH3 OCH2 CHO∗ → CH3 CHO + h For EE :
CH3 CH2 OCH2 CH2 OH + O2 −→CH3 CH2 OCH2 CHO∗
CH3 CH2 OCH2 CHO∗ → CH3 CHO + h When EM or EE vapors passed through the surface of the MgO thin ﬁlm, they were catalytically oxidized by O2 in the air. The electronically excited methoxy acetaldehyde (CH3 OCH2 CHO*) or ethoxy acetaldehyde (CH3 CH2 OCH2 CHO*) could be produced and absorbed on the MgO ﬁlm during the reaction and generated photoemission when they returned to their ground states. 4. Conclusions The EE and EM vapors sensor based on MgO thin ﬁlm had been investigated for the ﬁrst time in this paper. The results showed that the sensor possessed rapid response, high sensitivity, satisfactory durability, and excellent speciﬁcity to EE and EM among some possible coexistence substances in air. The sensor can detect EE and EM whether the gas exist alone or together. It shows the prospect for EE and EM determination in industry and environment monitoring. This paper is also valuable for the future research to develop cataluminescence sensors based on thin ﬁlm catalysts. Acknowledgements The authors gratefully thank for the ﬁnancial support by the National Natural Science Foundation of China (20677013), Natural Science Foundation of Guangdong Province, China (8151009101000130). References  B.D. Hardin, Reproductive toxicity of the glycol ethers, Toxicology 27 (1983) 91–102.
 Fairhurst, R. Knight, T.C. Marrs, J.W. Scawin, M.S. Spurlock, D.W. Swanston, Percutaneous toxicity of ethylene glycol monomethyl ether and dipropylene glycol monomethyl ether in the rat, Toxicology 57 (1989) 209–215.  K.L. Cheever, T.F. Swearengin, R.M. Edwards, B.K. Nelson, D.W. Werren, D.L. Conover, D.G. DeBord, 2-Methoxyethanol metabolism, embryonic distribution, and macromolecular adduct formation in the rat: the effect of radiofrequency radiation-induced hyperthermia, Toxicol. Lett. 122 (2001) 53–67.  M. Schenker, Epidemiologic study of reproductive and other health effects among workers employed in the manufacture of semiconductors, Final Report to the Semiconductor Industry Association, University of California (USA), Davis, 1992.  R.H. Gray, A. Correa, Ethylene glycol ethers and reproductive health in semiconductor workers, in: Abstracts of the International Symposium on Health Hazards of Glycol Ethers, 1994, pp. VII–12.  C.H. Luk, C.L. Mak, K.H. Wong, Characterization of strontium barium niobate ﬁlms prepared by sol–gel process using 2-methoxyethanol, Thin Solid Films 298 (1997) 57–61.  A. Veber, S. Kunej, D. Suvorov, Synthesis and microstructural characterization of Bi12 SiO20 (BSO) thin ﬁlms produced by the sol–gel process, Ceram. Int. 36 (2010) 245–250.  G. Johanson, Aspects of biological monitoring of exposure to glycol ethers, Toxicol. Lett. 43 (1988) 5–21.  B. Hubner, K. Geibel, J. Angerer, GC-determination of propylene and diethylene glycol ethers in urine, Fres. J. Anal. Chem. 342 (1992) 746–748.  M. Venier, G. Adami, F. Larese, G. Maina, N. Renzi, Percutaneous absorption of 5 glycol ethers through human skin in vitro, Toxicol. In Vitro 18 (2004) 665–671.  V. Cote, G. Kos, R. Mortazavi, P.A. Ariya, Microbial and “de novo” transformation of dicarboxylic acids by three airborne fungi, Sci. Total Environ. 390 (2008) 530–537.  C.T. Galo, O.C. Ricardo, Synthesis and characterization of bimetallic Ni–Cu colloids, Mater. Res. Bull. 33 (1998) 1599–1608.  M. Breysse, B. Claudel, L. Faure, M. Guenin, R.J. Williams, Chemiluminescence during the catalysis of carbon monoxide oxidation on a thoria surface, J. Catal. 45 (1976) 137–144.  M. Akagawa, A new chemiluminescence-based sensor for discriminating and determining constituents in mixed gases, Sens. Actuators B 29 (1995) 94–100.  K. Utsunomiya, M. Nakagawa, T. Tomiyama, I. Yamamoto, Y. Matsuura, S. Chikamori, T. Wada, N. Yamashita, Y. Yamashita, An adsorption-luminescent Al2 O3 sheet for determining vapor of odor substances in air, Sens. Actuators B 13–14 (1993) 627–628.  M. Nakagawa, S. Kawabata, K. Nishiyama, K. Utsunomiya, I. Yamamoto, T. Wada, Y. Yamashita, N. Yamashita, Analytical detection system of mixed odor vapors using chemiluminescence-based gas sensor, Sens. Actuators B 34 (1996) 334–338.  T. Okabayashi, N. Matsuo, I. Yamamoto, K. Utsunomiya, N. Yamashita, M. Nakagawa, Temperature-programmed sensing for gas identiﬁcation using the cataluminescence-based sensors, Sens. Actuators B 108 (2005) 515–520.  T. Okabayashi, T. Fujimito, I. Yamamoto, K. Utsunomiya, T. Wada, Y. Yamashita, M. Nakagawa, High sensitive hydrocarbon gas sensor utilizing cataluminescence of ␥-Al2 O3 activated with Dy3+ , Sens. Actuators B 64 (2000) 54–58.  G.M. Huang, Y. Lv, S.C. Zhang, C.D. Yang, X.R. Zhang, Development of an aerosol chemiluminescent detector coupled to capillary electrophoresis for saccharide analysis, Anal. Chem. 77 (2005) 7356–7365.  Y.F. Zhu, J.J. Shi, Z.Y. Zhang, C. Zhang, X.R. Zhang, Development of a gas sensor utilizing chemiluminescence on nanosized titanium dioxide, Anal. Chem. 74 (2002) 120–124.  Z.Y. Zhang, C. Zhang, X.R. Zhang, Development of a chemiluminescence ethanol sensor based on nanosized ZrO2 , Analyst 127 (2002) 792–796.  F. Wen, S.C. Zhang, N. Na, Y.Y. Wu, X.R. Zhang, Development of a sensitive gas sensor by trapping the analytes on nanomaterials and in situ cataluminescence detection, Sens. Actuators B 141 (2009) 168–173.  X.A. Cao, Z.Y. Zhang, X.R. Zhang, A novel gaseous acetaldehyde sensor utilizing cataluminescence on nanosized-BaCO3 , Sens. Actuators B 99 (2004) 30–35.  X.A. Cao, X.R. Zhang, A research on determination of explosive gases utilizing cataluminescence sensor array, Luminescence 20 (2005) 243–250.  H.R. Tang, Y.M. Li, C.B. Zheng, J. Ye, X.D. Hou, Y. Lv, An ethanol sensor based on cataluminescence on ZnO nanoparticles, Talanta 72 (2007) 1593–1597.  C. Yu, G.H. Liu, B.L. Zuo, Y.J. Tang, T. Zhang, A novel gaseous pinacolyl alcohol sensor utilizing cataluminescence on alumina nanowires prepared by supercritical ﬂuid drying, Anal. Chim. Acta 618 (2008) 204–209.  L. Tang, Y.M. Li, K.L. Xu, X.D. Hou, Y. Lv, Sensitive and selective acetone sensor based on its cataluminescence from nano-La2 O3 surface, Sens. Actuators B 132 (2008) 243–249.  X.A. Cao, G.M. Feng, H.H. Gao, X.Q. Luo, H.L. Lu, Nanosized ␥-Al2 O3 + Nd2 O3 based cataluminescence sensor for ethylene dichloride, Luminescence 20 (2005) 104–108.  K.W. Zhou, X.J. Ji, N. Zhang, X.R. Zhang, On-line monitoring of formaldehyde in air by cataluminescence-based gas sensor, Sens. Actuators B 119 (2006) 392–397.  Y.Y. Wu, S.C. Zhang, X. Wang, N. Na, Z.X. Zhang, Development of a benzaldehyde sensor utilizing chemiluminescence on nanosized Y2 O3 , Luminescence 23 (2008) 376–380.  Z.M. Rao, L.J. Liu, J.Y. Xie, Y.Y. Zeng, Development of a benzene vapour sensor utilizing chemiluminescence on Y2 O3 , Luminescence 23 (2008) 163–168.  X.A. Cao, W.F. Wu, N. Chen, Y. Peng, Y.H. Liu, An ether sensor utilizing cataluminescence on nanosized ZnWO4 , Sens. Actuators B 137 (2009) 83–87.
Y. Tao et al. / Sensors and Actuators B 148 (2010) 292–297  X.A. Cao, Y. Tao, L.L. Li, Y.H. Liu, Y. Peng, J.W. Li, An ethyl acetate sensor utilizing cataluminescence on Y2 O3 nanoparticles, Luminescence (2009), doi:10.1002/bio.1174.  C.C. Wu, X.A. Cao, Q. Wen, Z.H. Wang, Q.Q. Gao, H.C. Zhu, A vinyl acetate sensor based on cataluminescence on MgO nanoparticles, Talanta 79 (2009) 1223–1227.  N. Na, S.C. Zhang, S. Wang, X.R. Zhang, A catalytic nanomaterial-based optical chemo-sensor array, J. Am. Chem. Soc. 128 (2006) 14420–14421.  A. Galdikas, A. Mironas, D. Senulienc, A. Setkus, Gas sensitivity studies by optical spectroscopy below the absorption edge in tin oxide thin ﬁlm sensors, Thin Solid Films 323 (1998) 275–284.  A. Chiorino, G. Ghiotti, F. Prinetto, M.C. Carotta, M. Gallana, G. Martinelli, Characterization of materials for gas sensors. Surface chemistry of SnO2 and MoOx –SnO2 nano-sized powders and electrical responses of the related thick ﬁlms, Sens. Actuators B 59 (1999) 203–209.  S.K. Shukla, G.K. Parashar, A.P. Mishra, Puneet Misra, B.C. Yadav, R.K. Shukla, L.M. Bali, G.C. Dubey, Nano-like magnesium oxide ﬁlms and its signiﬁcance in optical ﬁber humidity sensor, Sens. Actuators B 98 (2004) 5–11.  S. Bertarione, D. Scarano, A. Zecchina, V. Johanek, J. Hoffmann, S. Schauermann, J. Libuda, G. Rupprechter, H.J. Freund, Surface reactivity of Pd nanoparticles supported on polycrystalline substrates as compared to thin ﬁlm model catalysts: infrared study of CH3 OH adsorption, J. Catal. 223 (2004) 64–73.  A.M. Vos, X. Rozanska, R.A. Schoonheydt, R.A. van Santen, F. Hutschka, J. Hafner, A theoretical study of the alkylation reaction of toluene with methanol catalyzed by acidic mordenite, J. Am. Chem. Soc. 123 (2001) 2799–2809.  S.P. Bates, W.J.M. van Well, R.A. van Santen, B. Smit, Energetics of n-alkanes in zeolites: a conﬁgurational-bias Monte Carlo investigation into pore size dependence, J. Am. Chem. Soc. 118 (1996) 6753–6759.
 J. Hu, K.L. Xu, Y.Z. Jia, Y. Lv, Y.B. Li, X.D. Hou, Oxidation of ethyl ether on borate glass: chemiluminescence, mechanism, and development of a sensitive gas sensor, Anal. Chem. 80 (2008) 7964–7969.
Biographies Ying Tao completed her undergraduate studies in the Chemical Technology Institute, Wuhan University of Science and Technology, China. And is currently a postgraduate student at the Environmental Science and Engineering Institute, Guangzhou University, China. Her major is Environmental Chemistry and focus on cataluminescence and the application of the gas sensor. Xiaoan Cao received her BS degree in 1982 from Department of Chemistry, Jiangxi University, China. She is currently working in the Institute of Environmental Science and Engineering, Guangzhou University. She has been a professor of Guangzhou University since 2002. Her interest is in the investigation of cataluminescence and the application to the gas sensor. Yan Peng received her MS degree in 2001 from East China Geological Institute (now, East China Institute of Technology) China. Now she is a PhD candidate of China University of Geosciences and majors in environmental engineering. Her research interest is focused mainly on analytical of volatile organic compounds in indoor air. Yonghui Liu received her PhD degree in 2004 from Dalian University of Science & Technology, China. Now she works in Institute of Environmental Science & Engineering at Guangzhou University, China. Her major research interests focus mainly on VOCs detection and degradation.