CN109115834A

CN109115834A - A kind of ppb grades of NO2Gas sheet type sensor and preparation method

Info

Publication number: CN109115834A
Application number: CN201810864082.2A
Authority: CN
Inventors: 李强; 郑晓虹; 李鑫; 沈艺波; 戴梦婷; 王冰
Original assignee: East China Normal University
Current assignee: East China Normal University
Priority date: 2018-08-01
Filing date: 2018-08-01
Publication date: 2019-01-01

Abstract

The invention discloses a ppb level NO ₂ gas chip sensor and a preparation method. The mesoporous WO ₃ is synthesized by a hard template method; the NO ₂ gas chip sensor is prepared by using YSZ as a solid electrolyte and mesoporous WO ₃ as a sensitive electrode. The NO ₂ chip sensor prepared by the invention has the advantages of simple structure, high sensitivity, low detection limit (60ppb), good selectivity and repeatability and the like.

Description

A kind of ppb grades of NO2Gas sheet type sensor and preparation method

Technical field

The present invention relates to NO₂Sensor technical field, especially a kind of mesoporous tungsten oxide is as sensitive electrode NO₂Gas piece The preparation method of formula sensor.Mesoporous WO₃Powder is made by hard template method, then with mesoporous WO₃NO is prepared for sensitive electrode₂Piece Formula sensor.

Background technique

With the development of economy and society, environmental pollution is increasingly severe.The combustion-type NO of fossil fuel₂Pollutant it is main Source.NO₂It would generally cause acid rain and photochemical fog, seriously threaten the ecological balance and the health of the mankind.Many countries Environmental legislation mention, NO in air₂Maximum acceptable concentration be 5ppm.NO in atmosphere₂Concentration be about 0.01ppm, but U.S. Environmental Protection Department think be more than 0.65ppm NO₂There is sizable threat to human health.Environmental Protection Agency is also shown that Child on long-term, which is exposed to 53ppb or more, will lead to serious breathing problem.Therefore, China more payes attention to environmental improvement, urgent uncommon It hopes and develops highly sensitive, ppb grades NO₂Sensor.NO at present₂Detection method have infra-red sepectrometry, chemoluminescence method etc., this A little method instruments are complicated, are not easy on-line continuous monitoring.In comparison electrochemistry sheet type sensor is because its structure is simple, cost It is low, can on-line continuous monitoring and have been to be concerned by more and more people.Sound of the sensitive electrode to sensor in electrochemical sensor Answer, sensitivity and selectivity etc. all have a great impact.But general electrochemical sensor can only detect ppm grades of NO₂, can not Fully meet the requirement of environment measuring (ppb grades).

Summary of the invention

The object of the present invention is to provide a kind of ppb grades of (60ppb) NO of high sensitivity₂Gas sheet type sensor and preparation side Method, preparation method is with mesoporous WO₃NO is made for sensitive electrode₂Gas sheet type sensor；Its NO₂Sheet type sensor has structure Simply, be readily synthesized, high sensitivity, detection limit it is low, selectivity and it is reproducible the advantages that.

Realizing the specific technical solution of the object of the invention is:

A kind of ppb grades of NO of high sensitivity₂The preparation method of gas sheet type sensor, this method comprising the following specific steps

Step 1: the preparation of hard template SBA-15

ⅰ)P123(EO₂₀PO₇₀EO₂₀) and 2mol/L HCl, H₂O is mixed according to mass ratio 2:60:15, stirs 30-60min It is completely dissolved to P123；

II) by I) in solution be put into water-bath, when temperature reaches 40 DEG C, according to solution and ethyl orthosilicate (TEOS) ethyl orthosilicate, 40 DEG C of stirring 24-48h are added dropwise in mass ratio 20:1；

III) by II) in solution be transferred to reaction kettle, 100 DEG C of reaction 12-24h are filtered, washed, 80 DEG C of dry 12-24h；

IV) dried powder is placed in Muffle furnace, 550 DEG C of burning 6-10h obtain SBA-15；

Step 2: mesoporous WO₃Synthesis

I) silico-tungstic acid with ethyl alcohol is that 7:20 is mixed in mass ratio, stirring to silico-tungstic acid is dissolved；

II) SBA-15 adds to I) obtained in silico-tungstic acid solution (mass ratio 1:5), ultrasonic 10-30min, by SBA- Bubble discharge in 15 ducts；

III) II) obtained in solution stir 12-24h at room temperature, dry 12-24h at 80 DEG C, then 550 DEG C of burning 4h, obtain To solid mixture；

IV) HF and H₂O is mixed to get the HF solution of 3mol/L according to volume ratio 1:11.III) obtained in solid and 3mol/ The HF solution of L is mixed according to mass ratio 1:30, stirs 12-24h, and filtration washing naturally dry obtains mesoporous WO₃；

Step 3:NO₂The preparation of gas sheet type sensor

I) mesoporous WO₃It is mixed with ethyl cellulose and terpinol according to mass ratio 10:1:20, with planet vibrator 100r/min ball milling 2-5h, obtains mesoporous WO₃Slurry.

II) 8YSZ (8%Y₂O₃Adulterate ZrO₂) cast sheet is cut into the thin slice of 1 × 1cm, tow sides are stamped with silk-screen printing Pt electrode, and Pt are drawn respectively from two electrodes, 1400 DEG C of burning 2-4h in Muffle furnace；

III) by II) obtained in the side of piece pass through mesoporous WO in silk-screen printing on platinum slurry₃Slurry, and in Muffle 2-4h is burnt in furnace at 600 DEG C and obtains ppb grades of NO₂Gas sheet type sensor.

With mesoporous WO₃Do sensitive electrode, the sensitivity of sheet type sensor greatly improves that (S=51.76mV/decade, S are The slope of working curve, working curve are△ EMF is sensor in NO₂In It is NO with the potential difference C in background gas₂The concentration b of gas is the intercept of working curve), favorable reproducibility, stability height.

The present invention is using SBA-15 as the mesoporous WO of templated synthesis₃Sensitive electrode, and NO is assembled with it₂Sheet type sensor；It reduces The detectable limit (ppb grades) of sensor, improves the sensitivity of sensor.Sheet type sensor structure produced by the present invention is simple, It is at low cost, the production efficiency of sensor can be greatly improved, convenient for integrated.

Detailed description of the invention

Fig. 1 is mesoporous WO prepared by the embodiment of the present invention 4₃XRD diagram；

Fig. 2 is mesoporous WO prepared by the embodiment of the present invention 4₃TEM figure；

Fig. 3 is the working curve of sensor prepared by inventive embodiments 4；

Fig. 4 is sensor made from the embodiment of the present invention 4, and test temperature is the reperformance test knot in 30 days at 500 DEG C Fruit figure.

Specific embodiment

Below in conjunction with specific embodiment, the present invention will be further described.

Embodiment 1

(a) preparation of hard template SBA-15

ⅰ)4g P123(EO₂₀PO₇₀EO₂₀) it is dissolved in the HCl+30g H that 120g concentration is 2mol/L₂In the solution of O, stirring 30min to P123 is completely dissolved；

II) by I) in solution be put into water-bath, when temperature reaches 40 DEG C, 7.52g ethyl orthosilicate is added dropwise (TEOS), it stirs for 24 hours for 40 DEG C；

III) by II) in solution be transferred to reaction kettle, 100 DEG C of reaction 12h are filtered, washed, 80 DEG C of dry 12h；

IV) dried powder is placed in Muffle furnace, 550 DEG C of burning 6h obtain SBA-15；

(b) mesoporous WO₃Synthesis

I) 1.75g silico-tungstic acid is dissolved in 5g ethyl alcohol；

II) 1g SBA-15 adds to 5g I) obtained in silico-tungstic acid solution, ultrasonic 10min, by the gas in the duct SBA-15 Bubble discharge；

III) by II) obtained in solution stir 12h, dry 12h at 80 DEG C at room temperature, then 550 DEG C of burning 4h, consolidate Body mixture；

IV) by 1g III) obtained in solid 12h filtration washing naturally dry is stirred in the solution of 30gHF, obtain mesoporous WO₃；

(c)NO₂The preparation of gas sheet type sensor

I) the mesoporous WO of 0.5g₃It is mixed with 0.05g ethyl cellulose and 1g terpinol, with planet vibrator 100r/min Ball milling 2h obtains mesoporous WO₃Slurry；

II) 8YSZ (8%Y₂O₃Adulterate ZrO₂) cast sheet is cut into the thin slice of 1 × 1cm, tow sides are stamped with silk-screen printing Pt electrode, and Pt are drawn respectively from two electrodes, 1400 DEG C of burning 2h in Muffle furnace；

III) II) obtained in the side of piece pass through mesoporous WO in silk-screen printing on platinum slurry₃Slurry, and in Muffle furnace In burn 2h at 600 DEG C and obtain NO₂Sheet type sensor；

(d) gained NO₂Sheet type sensor is when operating temperature is 500 DEG C, to 0.06-10ppmNO₂Sensitivity reach 47mV/decade。

Embodiment 2

(a) preparation of hard template SBA-15

ⅰ)32g P123(EO₂₀PO₇₀EO₂₀) it is dissolved in the HCl+240g H that 960g concentration is 2mol/L₂In the solution of O, stir 60min to P123 is mixed to be completely dissolved；

II) by I) in solution be put into water-bath, when temperature reaches 40 DEG C, 60.16g ethyl orthosilicate is added dropwise (TEOS), 40 DEG C of stirring 48h；

III) by II) in solution be transferred to reaction kettle, 100 DEG C of reactions for 24 hours, are filtered, washed, 80 DEG C of dryings are for 24 hours；

IV) dried powder is placed in Muffle furnace, 550 DEG C of burning 10h obtain SBA-15；

(b) mesoporous WO₃Synthesis

I) 14g silico-tungstic acid is dissolved in 40g ethyl alcohol；

II) 8g SBA-15 adds to 40g I) obtained in silico-tungstic acid solution, ultrasonic 30min will be in the duct SBA-15 Bubble discharge；

III) by II) obtained in solution stir at room temperature for 24 hours, at 80 DEG C it is dry for 24 hours, then 550 DEG C of burning 4h, consolidate Body mixture；IV) by 8g III) obtained in solid stirred for 24 hours in 240gHF solution, filtration washing naturally dry is situated between Hole WO₃；

(c)NO₂The preparation of gas sheet type sensor

I) the mesoporous WO of 4g₃It is mixed with 0.4g ethyl cellulose and 8g terpinol, with planet vibrator 100r/min ball 5h is ground, mesoporous WO is obtained₃Slurry；

II) 8YSZ (8%Y₂O₃Adulterate ZrO₂) cast sheet is cut into the thin slice of 1 × 1cm, tow sides are stamped with silk-screen printing Pt electrode, and Pt are drawn respectively from two electrodes, 1400 DEG C of burning 4h in Muffle furnace；

III) by II) obtained in the side of piece pass through mesoporous WO in silk-screen printing on platinum slurry₃Slurry, and in Muffle 4h is burnt in furnace at 600 DEG C and obtains NO₂Sheet type sensor；

(d) gained NO₂Sheet type sensor is when operating temperature is 500 DEG C, to 0.06-10ppmNO₂Sensitivity reach 48.2mV/decade。

Embodiment 3

(a) preparation of hard template SBA-15

ⅰ)16g P123(EO₂₀PO₇₀EO₂₀) it is dissolved in the HCl+120g H that 480g concentration is 2mol/L₂In the solution of O, stir 50min to P123 is mixed to be completely dissolved；

II) by I) in solution be put into water-bath, when temperature reaches 40 DEG C, 30.08g ethyl orthosilicate is added dropwise (TEOS), 40 DEG C of stirring 40h；

III) by II) in solution be transferred to reaction kettle, 100 DEG C of reaction 20h are filtered, washed, 80 DEG C of dry 20h；

IV) dried powder is placed in Muffle furnace, 550 DEG C of burning 9h obtain SBA-15；

(b) mesoporous WO₃Synthesis

I) 7g silico-tungstic acid is dissolved in 20g ethyl alcohol；

II) 4g SBA-15 adds to 20g I) obtained in silico-tungstic acid solution, ultrasonic 25min will be in the duct SBA-15 Bubble discharge；

III) by II) obtained in solution stir 20h, dry 20h at 80 DEG C at room temperature, then 550 DEG C of burning 4h, consolidate Body mixture；

IV) by 4g III) obtained in solid 20h is stirred in the solution of 120gHF, filtration washing naturally dry is situated between Hole WO₃；

(c)NO₂The preparation of gas sheet type sensor

I) by the mesoporous WO of 2g₃It is mixed with 0.2g ethyl cellulose and 4g terpinol, with planet vibrator 100r/min Ball milling 4h obtains mesoporous WO₃Slurry；

II) 8YSZ (8%Y₂O₃Adulterate ZrO₂) cast sheet is cut into the thin slice of 1 × 1cm, tow sides are stamped with silk-screen printing Pt electrode, and Pt are drawn respectively from two electrodes, 1400 DEG C of burning 3.5h in Muffle furnace；

III) by II) obtained in the side of piece pass through mesoporous WO in silk-screen printing on platinum slurry₃Slurry, and in Muffle 3.5h is burnt in furnace at 600 DEG C and obtains NO₂Sheet type sensor；

(d) gained NO₂Sheet type sensor is when operating temperature is 500 DEG C, to 0.06-10ppmNO₂Sensitivity reach 49mV/decade。

Embodiment 4

(a) preparation of hard template SBA-15

ⅰ)8g P123(EO₂₀PO₇₀EO₂₀) it is dissolved in the HCl+60g H that 240g concentration is 2mol/L₂In the solution of O, stirring 40min to P123 is completely dissolved；

II) by I) in solution be put into water-bath, when temperature reaches 40 DEG C, 15.04g ethyl orthosilicate is added dropwise (TEOS), 40 DEG C of stirring 36h；

III) by II) in solution be transferred to reaction kettle, 100 DEG C of reaction 16h are filtered, washed, 80 DEG C of dry 16h；

IV) dried powder is placed in Muffle furnace, 550 DEG C of burning 8h obtain SBA-15；

(b) mesoporous WO₃Synthesis

I) 3.5g silico-tungstic acid is dissolved in 10g ethyl alcohol；

II) 2g SBA-15 adds to 10g I) obtained in silico-tungstic acid solution, ultrasonic 20min will be in the duct SBA-15 Bubble discharge；

III) by II) obtained in solution stir 16h, dry 16h at 80 DEG C at room temperature, then 550 DEG C of burning 4h, consolidate Body mixture；

IV) by 2g III) obtained in solid 16h is stirred in the solution of 60ml 3mol/LHF, filtration washing dries in the air naturally It is dry, obtain mesoporous WO₃；It can be seen that the mesoporous WO that the present invention synthesizes by the XRD in Fig. 1₃For monocline WO₃, cell parameter is andDo not occur SiO in XRD₂Peak, pattern of descriptive parts removes more thorough Bottom.The mesoporous WO of Fig. 2₃TEM can be seen that mesoporous WO₃There is elongated pipeline, aperture is 7nm or so.

(c)NO₂The preparation of gas sheet type sensor

I) by the mesoporous WO of 1g₃It is mixed with 0.1g ethyl cellulose and 2g terpinol, with planet vibrator 100r/min Ball milling 3h obtains mesoporous WO₃Slurry；

III) by II) obtained in the side of piece pass through mesoporous WO in silk-screen printing on platinum slurry₃Slurry, and in Muffle 2h is burnt in furnace at 600 DEG C and obtains NO₂Sheet type sensor；

(d) from figure 3, it can be seen that testing at 500 DEG C sensor, to 0.06-10ppmNO₂Sensitivity reach 51.76mV/decade, degree of fitting reach 99.4%.From fig. 4, it can be seen that be repeated four times test in 30 days, working curve it is oblique Rate is basically unchanged (between 50.94-51.76), and intercept changes very small (between 72.7-75.1), and four times test curve weighs substantially It is combined.Illustrate that sensor has repeatability and stability well.

Claims

_1. a preparation method of ppb level NO gas chip sensor, is characterized in that, the method comprises the following concrete steps:

Step 1: Preparation of Hard Template SBA-15

ⅰ) EO ₂₀ PO ₇₀ EO ₂₀ ie P123 and 2mol/L HCl and H ₂ O were mixed according to the mass ratio of 2:60:15, and stirred for 30-60min until P123 was completely dissolved;

ii) Put the solution in i) into a water bath, when the temperature reaches 40℃, add ethyl orthosilicate dropwise according to the mass ratio of solution and ethyl orthosilicate (TEOS) 20:1, stir at 40℃ for 24- 48h;

iii) Transfer the solution in ii) to the reaction kettle, react at 100°C for 12-24h, filter, wash, and dry at 80°C for 12-24h;

iv) Put the dried powder in a muffle furnace and burn it at 550°C for 6-10h to obtain SBA-15;

Step 2: Synthesis of Mesoporous Tungsten Oxide

ⅰ) Mix silicotungstic acid and ethanol in a mass ratio of 7:20, and stir until the silicotungstic acid dissolves;

ii) adding SBA-15 to the silicotungstic acid solution obtained in i), ultrasonicating for 10-30min, to discharge the air bubbles in the pores of SBA-15; the mass ratio of SBA-15 to silicotungstic acid is 1:5;

iii) The solution obtained in ii) was stirred at room temperature for 12-24 h, dried at 80 °C for 12-24 h, and then burned at 550 °C for 4 h to obtain a solid mixture;

iv) HF and H ₂ O were mixed in a volume ratio of 1:11 to obtain a 3mol/L HF solution; the solid obtained in iii) was mixed with a 3mol/L HF solution in a mass ratio of 1:30, stirred for 12-24h, and filtered. Wash and dry naturally to obtain mesoporous WO ₃ ;

Step ₃ : Fabrication of NO2 Gas Chip Sensor

ⅰ) Mix mesoporous WO ₃ with ethyl cellulose and terpineol, and use a planetary vibrating ball mill at 100 r/min for ball milling for 2-5 hours to obtain a mesoporous WO ₃ slurry; the mesoporous WO ₃ , ethyl cellulose and The mass ratio of terpineol is 10:1:20;

ii) Cut the 8YSZ cast sheet into 1×1cm slices, print Pt electrodes on both sides by screen printing, and draw out Pt wires from the two electrodes respectively, and burn them in a muffle furnace at 1400°C for 2-4h; The 8YSZ is 8% Y ₂ O ₃ doped ZrO ₂ ;

iii) The mesoporous WO ₃ paste is screen-printed on one side of the obtained sheet in ii) on the platinum paste, and fired in a muffle furnace at 600° C. for 2-4 h to obtain the ppb-level NO ₂ gas chip sensor.

2. A ppb level NO ₂ gas chip sensor prepared by the method of claim 1.