CN100405049C - Gas sensor made of SnO2 cluster nano-rod - Google Patents

Abstract

The present invention relates to a SnO2 bundling nanometer rod gas sensor which belongs to the technical field of a sensor. The SnO2 bundling nanometer rod gas sensor carries out the procedures of mix, grinding, reaction and the like to A component mixtures containing polyethylene glycol pentaether, polyethylene glycol enneadether, SnCl4 and molten salt and B component containing the polyethylene glycol pentaether, the polyethylene glycol enneadether, KBH4 and the molten salt; the A component mixtures and the B component are washed by acetone and baked to obtain the precursor of the SnO2 nanometer rod; the baked precursor of the SnO2 nanometer rod is repeatedly washed by ionized water to remove NaCl molten salt and KCl molten salt and reaction residue; and samples repeatedly washed are separated and baked to manufacture SnO2 bundling nanometer rod gas sensitive material. The SnO2 bundling nanometer rod material gas sensor has the advantages of high sensibility and high selectivity to gas such as alcohol, H2, etc., high stability, etc., and has good practical application value.

Description

SnO 2The cluster nano-rod gas sensor

Technical field:

The present invention relates to a kind of SnO ₂The cluster nano-rod gas sensor belongs to sensor technical field.

Background technology:

In the gas sensor technical field, sensitivity, selectivity and the stability (Sensitivity, Selectivity and Stability) that improve gas sensor are the targets that people make great efforts always.SnO ₂As a kind of n type metal oxide semiconductor material, since have chemical stability good, be the focus of gas sensor research to characteristics such as some gas sensitivity height and cost are low always, so far have the history in more than 30 year, commercial goods gasification photosensitive elements major part is by polycrystalline SnO at present ₂Powder or film are made.But with regard to SnO ₂Material itself, sensitivity and selectivity are unsatisfactory.Therefore, in most cases people adopt at SnO ₂In mix selectivity and the sensitivity that other material improves gas sensor.With SnO ₂Be matrix material, mix a small amount of additive or catalyzer and can make the SnO that gases such as alcohol, hydrogen, sulfuretted hydrogen, carbon monoxide and methane is had the selective sensitivity effect ₂Gas sensor.Though make SnO by the method for mixing ₂Air-sensitive performance has obtained certain improvement, but still can't satisfy people's requirement.Along with developing rapidly of science and technology, sensing element especially sensing material is had higher requirement.Therefore exploration has the novel sensing material highly sensitive, that selectivity good and stability is high, the making novel sensor is the target that people pursue always.

In recent years, people have carried out SnO ₂Nano particle, SnO ₂Nano belt, SnO ₂Various nanostructured SnO such as nanometer rods ₂The research of material and gas-sensitive property thereof, SnO ₂The nanometer of gas sensitive becomes and improves SnO ₂One of important channel of material sensitivity.Studies show that, with respect to traditional polycrystalline SnO ₂Material and SnO ₂Nano-particle material is used single SnO ₂The gas sensor that nano belt/line monodimension nanometer material is made has very high sensitivity (far above using SnO ₂The sensitivity of the gas sensor that nano particle is made), and good stability, the sensor that has advantage such as can also work at normal temperatures.Studied single SnO as people such as G.Sberveglieri ₂The gas-sensitive property of nano belt found that SnO ₂Nano belt is to CO, NO ₂Very responsive Deng toxic gas in the environment and alcohol gas.Studies show that, at 400 ℃, be 4160% to the sensitivity of the ethanol of 250ppm, to the NO of 0.5ppm ₂Then be 1550%.But because be subjected to that cost of manufacture is high, the restriction of testing conditions harshness etc., at present, these sensors only are in conceptual phase in a few experiments chamber, also have a very long segment distance from practicability.

Summary of the invention:

The objective of the invention is to overcome the deficiency of prior art, and provide a kind of to ethanol with to H ₂Have highly sensitive, selectivity good, and the high SnO of stability ₂The cluster nano-rod gas sensor.

I, SnO of the present invention ₂The cluster nano rod air-sensitive material is prepared by following method:

(1) preparation of A group thing

A. a certain amount of SnCl weighs with scale ₄5H ₂O puts into agate mortar and grinds 30～60min;

B. a certain amount of sodium chloride of pressing certain mol proportion preparation of weighing and potassium chloride salt-mixture are put into agate mortar grinding 30～60min as fused salt, and the molar ratio range of sodium chloride and potassium chloride salt-mixture is: 1: 0.5～1: 1.5;

C. ground SnCl ₄5H ₂O powder and fused salt mix by 1: 3～1: 5 mass ratio, grind 10～30min again in agate mortar;

D. polyoxyethylene pentaether, polyoxyethylene nine ethers are mixed by 1: 1 mass ratio, stir, be mixed with mixing material;

E. measure the certain amount of mixed solution body, pour the SnCl that makes by above-mentioned (1) c step into ₄5H ₂In the potpourri of O and fused salt, SnCl ₄5H ₂The gross mass of O and molten salt mixture and the mass ratio of mixing material are: 1: 2～1: 4; Grind 15～30min, obtain A group thing.

(2) preparation of B group thing

A. according to SnCl in the A group thing ₄5H ₂The quality of O is according to SnCl ₄5H ₂O: KBH ₄Mass ratio be that 1: 1～1: 1.5 ratio takes by weighing KBH ₄, put into agate mortar and grind 30～60min;

B. ground KBH ₄The fused salt of preparing in powder and (1) b step by A group thing process for preparation mixes by 1: 3～1: 5 mass ratio, grinds 10～30min again in agate mortar;

C. measure the polyoxyethylene pentaether prepared in (1) the d step by A group thing and the mixing material of polyoxyethylene nine ethers, adds the KBH that above-mentioned (2) b step is prepared ₄In the potpourri of fused salt, KBH ₄With the gross mass of molten salt mixture and the mass ratio of polyoxyethylene pentaether and polyoxyethylene nine ether mixed liquors be 1: 2～1: 4; In agate mortar, grind 15～30min again, obtain B group thing.

(3) A group thing is mixed with the mass ratio of B group thing by 1: 1～1: 1.5, ground 1～2 hour, and in air, placed 2～4h, use the acetone cyclic washing then, it is 50 ℃～60 ℃ drying box inner drying 6～12 hours that the gained solid particle is put into temperature, and the pale solid powder that obtains is SnO ₂The precursor of nanometer rods.

(4) the good SnO of drying ₂Nanometer rods precursor powder cools off with stove then 600 ℃～800 ℃ roasting temperatures 2～6 hours.

(5) clean sample after the roasting repeatedly with deionized water, remove NaCl, KCl fused salt and reaction residue, repeatedly sample after cleaning separate, oven dry, promptly make SnO ₂The cluster nano rod air-sensitive material.

SnO ₂Preparation technology's flow process of cluster nano rod air-sensitive material as shown in Figure 1.The SnO for preparing ₂Cluster nano rod air-sensitive material such as Fig. 2, shown in Figure 3.

II, use SnO ₂The method of cluster nano-rod material new gas sensor is as follows:

With SnO ₂Cluster nano-rod is a gas sensitive material, makes the heater-type gas sensor.The manufacture craft of gas sensor divides following step to carry out:

A, preparation gas sensitive

With SnO ₂Cluster nano-rod is a material of main part, is that 3%～8% poly-vinyl alcohol solution is a bonding agent with concentration, prepares needed matrix material.Before making sensor element, material of main part is fully ground.When the gas sensor of making the ethanol sensitivity, at first with poly-vinyl alcohol solution with SnO ₂Cluster nano bar material furnishing pastel is stand-by; And making H ₂During responsive gas sensor, except that preparation as stated above, also need add a certain amount of SiO ₂Adjuvant, SiO ₂Adjuvant and SnO ₂The mass ratio of cluster nano-rod material of main part is 0.02: 1～0.05: 1, and is after the abundant ground and mixed of material, stand-by with poly-vinyl alcohol solution furnishing pastel.

B, tube core coating

With the gas sensitive of furnishing pasty state, adopt whirl coating evenly to be applied to the ceramic pipe outside surface that has made electrode, coating all covers electrode, and thickness is suitable, and thickness is even.

C, element sintering

After the good tube core drying of coating, be placed in the quartz boat, be positioned in the sintering furnace sintering 1～3 hour, sintering temperature is 450 ℃～550 ℃.

D, wire bonds and encapsulation

Ceramic die behind sintering is inserted the good heater strip of coiling in porcelain tube.Then contact conductor and heating wire bond are tied on base, sealed with the double-layer stainless steel net.Sensor element completes.

E, electrical heating are worn out

Sensor element is inserted in the special-purpose agingtable, wears out with the method for energising in 48 hours, and the element after aging can take out the test gas sensitive parameter.

The diagrammatic cross-section of the sensor element of making as shown in Figure 4.

The present invention is to ethanol with to H ₂Have highly sensitive, selectivity good, and stable advantages of higher.

Description of drawings:

Fig. 1 is SnO ₂Preparation technology's flow process of cluster nano rod air-sensitive material.

Fig. 2, Fig. 3 are SnO ₂Cluster nano bar material TEM picture.

Fig. 4 is SnO ₂Cluster nano-rod material gas sensor diagrammatic cross-section.

Fig. 5 is SnO ₂The variation relation of cluster nano-rod transducer sensitivity and gas concentration.

Fig. 6 is SnO ₂Cluster nano-rod H ₂The sensitivity of sensor and the variation relation between working temperature.

Embodiment:

It is described that the present invention not only is confined to embodiment.

One, SnO ₂The preparation of cluster nano bar material

Preparation section is described with the summary of the invention part, and preparation technology's flow process as shown in Figure 1.

Table 1 has been listed and has been prepared SnO among the present invention ₂6 kinds of examples of implementation of cluster nano bar material.

Table 1. preparation SnO ₂The examples of implementation of cluster nano bar material

Two. the example of making of gas sensor

1, alcohol gas sensor example of making

The alcohol gas sensor method for making is described with the summary of the invention part.Table 2 has been listed and has been made SnO among the present invention ₂6 kinds of examples of implementation of cluster nano bar material alcohol gas sensor.

Table 2. alcohol gas sensor example of making

2, H ₂The sensor production example

H ₂The sensor production method is described with the summary of the invention part.Table 3 has been listed and has been made SnO among the present invention ₂Cluster nano bar material H ₂6 kinds of examples of implementation of sensor.

Table 3.H ₂The sensor production example

Three, sensor performance

1, SnO ₂The sensitivity and the selectivity of cluster nano bar material alcohol gas sensor

Table 4 is for being used in the SnO of 600 ℃, 660 ℃, 710 ℃ and 760 ℃ roasting preparations respectively ₂Alcohol gas sensor SB1, the SB2 of cluster nano-rod material, SB3 and SB4 element sensitivity data table to different reducibility gas when working temperature is 300 ℃.As can be seen, except that toluene gas, element SB2 is high to all gases remolding sensitivity SB1, SB3 and SB4 from table 4 data.To concentration is the C of 1000ppm ₂H ₅The sensitivity of OH gas is for reaching 114.Secondly, that sensitivity is higher is CH ₃COCH ₃And HCHO, be the CH of 1000ppm to concentration ₃COCH ₃Sensitivity be 6.68, the sensitivity that to concentration is the HCHO of 1000ppm is 5.4.In 600～760 ℃ scope, sensitivity is risen earlier with the rising of sintering temperature and is afterwards descended, and sensitivity reaches maximum in the time of 660 ℃.From table 4 sensitivity data table as can be seen, the sensitivity resolving power of SB2 element, C ₂H ₅OH gas is to CH ₃COCH ₃Gas, resolving power α=17.1, C ₂H ₅OH gas is for HCHO gas, resolving power α=21.1, and to resolving power α＞35 of other several gases.

Table 4SnO ₂The sensitivity (β) of cluster nano bar material alcohol gas sensor

2, alcohol gas sensor sensitivity of SnO2 cluster nano bar material and gas concentration relation

Fig. 5 is the SnO 660 ℃ of roasting preparations ₂The alcohol gas sensor SB2 of cluster nano-rod material under 300 ℃ of working temperatures to the change curve of all gases sensitivity and gas concentration.As can be seen from Figure, during beginning, element sharply increases along with the increase of gas concentration the sensitivity of alcohol gas, and after 1000ppm concentration, sensitivity increases slowly, illustrates that the sensitivity of element begins to be tending towards saturated.For other several gases such as acetone, formaldehyde, benzene, to compare with alcohol gas, sensitivity changes along with the increase of gas concentration not quite, and this further specifies SnO ₂The cluster nano-rod material elements has high sensitivity and high selectivity to alcohol gas.

3, SnO ₂The H of cluster nano-rod material sensors ₂Relation between sensitivity and working temperature

Fig. 6 is the SnO that is used in 600 ℃, 660 ℃, 710 ℃ and 760 ℃ roasting preparations respectively ₂The H of cluster nano-rod material ₂Sensitive sensor SB1#, SB2#, SB3# and SB4# element are the H of 1000ppm to concentration under the different operating temperature ₂The sensitivity relation curve.As can be seen from the figure, working temperature is after 300 ℃, and sensor is to H ₂Sensitivity improve fast, when working temperature was 400 ℃, sensor was to H ₂Sensitivity reached higher level.In SB1#, SB2#, SB3# and four elements of SB4#, SB4# is to H ₂Gas sensitivity is all higher than SB1#, SB3# and SB4#, has arrived 25, can be used as H ₂The sensitive gas sensor is to H ₂Carry out actual detected.

Claims (1)

1. SnO ₂The cluster nano-rod gas sensor is characterized in that this gas sensor is by SnO ₂The cluster nano-rod gas sensitive material is made, SnO ₂The cluster nano-rod gas sensitive material prepares via following method:

(1) preparation of A group thing

A. a certain amount of SnCl weighs with scale ₄5H ₂O puts into agate mortar and grinds 30～60min;

B. a certain amount of sodium chloride of pressing certain mol proportion preparation of weighing and potassium chloride salt-mixture are put into agate mortar grinding 30～60min as fused salt, and the molar ratio range of sodium chloride and potassium chloride salt-mixture is: 1: 0.5～1: 1.5;

C. ground SnCl ₄5H ₂O powder and fused salt mix by 1: 3～1: 5 mass ratio, grind 10～30min again in agate mortar;

D. polyoxyethylene pentaether, polyoxyethylene nine ethers are mixed by 1: 1 mass ratio, stir, be mixed with mixing material;

E. measure the certain amount of mixed solution body, pour the SnCl that makes by above-mentioned (1) c step into ₄5H ₂In the potpourri of O and fused salt, SnCl ₄5H ₂The gross mass of O and molten salt mixture and the mass ratio of mixing material are 1: 2～1: 4; Grind 15～30min, obtain A group thing;

(2) preparation of B group thing

A. according to SnCl in the A group thing ₄5H ₂The quality of O is according to SnCl ₄5H ₂O: KBH ₄Mass ratio be that 1: 1～1: 1.5 ratio takes by weighing KBH ₄, put into agate mortar and grind 30～60min;

B. ground KBH ₄The fused salt of preparing in powder and (1) b step by A group thing process for preparation mixes by 1: 3～1: 5 mass ratio, grinds 10～30min again in agate mortar;

C. measure the polyoxyethylene pentaether prepared in (1) the d step by A group thing process for preparation and the mixed liquor of polyoxyethylene nine ethers, adds the KBH that above-mentioned (2) b prepares ₄In the potpourri of fused salt, KBH ₄With the gross mass of molten salt mixture and the mass ratio of polyoxyethylene pentaether and polyoxyethylene nine ether mixed liquors be 1: 2～1: 4; In agate mortar, grind 15～30min again, obtain B group thing;

(3) A group thing is mixed with the mass ratio of B group thing by 1: 1～1: 1.5, ground 1～2 hour, and in air, placed 2～4h, use the acetone cyclic washing then, it is 50～60 ℃ drying box inner drying 6～12 hours that the gained solid particle is put into temperature, obtains linen pressed powder and is SnO ₂The precursor of nanometer rods;

(4) the good SnO of drying ₂Nanometer rods precursor powder cools off with stove then 600 ℃～800 ℃ roasting temperatures 2～6 hours;

(5) clean sample after the roasting repeatedly with deionized water, remove NaCl, KCl fused salt and reaction residue, repeatedly sample after cleaning separate, oven dry, promptly make SnO ₂The cluster nano rod air-sensitive material.

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