DE102008044238A1 - Electrochemical gas sensor used for detecting or measuring chlorine, fluorine, bromine, oxygen or chlorine dioxide, comprises ionic liquid as electrolyte, where ionic liquid comprises organic, organometallic and/or inorganic additives - Google Patents

Abstract

An electrochemical gas sensor (1) comprises an ionic liquid as an electrolyte, where the ionic liquid comprises organic, organometallic and/or inorganic additives. Two electrodes are also included, which are electrically contacted with an ionic liquid and are electrically isolated from each other by a separator. The electrodes are made of a metal selected from a group consisting of copper, nickel, titanium, platinum, iridium, gold, palladium, silver, ruthenium, rhodium, their mixtures or oxides, or carbon.

Description

The The present invention relates to an electrochemical gas sensor, containing an ionic liquid as electrolyte. The ionic liquid has organic and / or organometallic and / or inorganic additives.

The fundamental measuring principle of a gas sensor is an electrochemical cell with at least two electrodes, which are in contact with each other via a second-order conductor (ion conductor). Gas can flow to the electrode on the side of the cell that is open to the atmosphere, where it is converted electrochemically. The generated from the implementation of electricity is proportional to the amount of gas present. From it the signal for the gas warning device is generated. As ionic conductors, the most varied systems are described in the patent literature. The most common is certainly the sulfuric acid used in sensors for common gases, such as CO, H ₂ S or O ₂ , and has been described since the 1960s (see Honeywell, 1967: US 3328277 B ).

Since some gases can only be converted into neutral electrochemical media, corresponding aqueous electrolytes with neutral or basic inorganic salts have been described as conductive salt (see City Technology, 1984: US 4474648 B ; Dräger, 1992: DE 4238337 C2 ).

A characteristic property of all sensor types described above is that the electrolytes described there are hygroscopic. On the one hand, this is intentional because the sensors are in the surrounding atmosphere interact and absorb water from it. In dry field environments, this property slows down the dehydration process of the cell. At high humidity, the Electrolyte, however, take up so much water that the sensor cell possibly bursts and electrolyte escapes. To this leakage to prevent electrolytes, the sensor cells must about 5 to 7 times their electrolyte fill volume than Reserve space in the sensor. That, in turn, is the general one Endeavor to miniaturize the cells.

One concept that seeks to circumvent this high humidity water absorption effect is to use organic liquids that need to be mixed with conductive salts to ensure ionic conductivity (eg, Catalyst Research Corp., 1978: US 4,169,779 B ). However, the advantage of high relative humidities reverses at low humidities or high ambient temperatures in a disadvantage, since the evaporated solvent can not be taken out of the atmosphere and thus is irretrievably lost for the sensor cell.

A Solution to this problem is in the use of ionic liquids (IL) as electrolytes. Ionian Liquids are defined as liquid salts with a melting point below 100 ° C. The salt-like structure brings with it that ionic liquids no have measurable vapor pressure. The possibility of variation these substances are great. The properties of ionic liquids depend decidedly on the type and number of organic Side chains and cations. So there are representatives who have a melting point below -40 ° C. Lots Ionic liquids are chemical as well as electrochemical very stable and have a high ionic conductivity. The Water absorption capacity of individual representatives is zero. The properties described above make ionic liquids to good electrolytes in electrochemical gas sensors.

The use of ionic liquids in gas sensors was the first to be reported by a Chinese research group under Cai et al. described in 2001 Cai et al. Journal of East China Normal University (article number 1000-5641 (2001) 03-0057-04 ]. They realized a very robust sensor for high sulfur dioxide concentrations.

Several patent applications were filed in quick succession concerning the use of ionic liquids in gas sensors (Bosch, GB 2395564 B ; MST Technology, US 7060169 B2 and Dräger, DE 102005020719 B3 ). While the Bosch patent GB 2395564 B describes very broad the use of ionic liquids, limited to the MST technology patent US 7060169 B2 on the use of pure imidazolium or pyridinium salts. The Dräger patent DE 102005020719 B3 puts the focus on the possibility of realizing an open gas sensor without diffusion membrane. The potential of this technique with regard to miniaturization of the sensors is disclosed by the published patent application (US Pat. DE 102004037312 A1 ) developed by Dräger.

All publications on ionic liquids in gas sensors have in common that in them ionic Liquids are used as a substitute for classical electrolytes.

No consideration in the writings on ionic liquids finds that the classical (aqueous) sensor systems often run on secondary reactions to increase their sensitivity or selectivity. Examples of this can be found in the disclosure or patent specifications of Millipore ( EP 1 600 768 A1 ), MST Analytics ( US 6248224 B1 ) and Dräger ( DE 102006014715 B3 ).

One reason for this may be that the chemical processes in ionic liquids differ fundamentally from those in aqueous or organic systems. Pioneer of this new chemistry, like the professors P. Wasserscheid (Angew Chem 2000, 112, 3926-3945) and KR Seddon (Pure Appl. Chem. Vol. 72, No. 7, pp. 1391-1398, 2000) , in this context, speak of a completely new and unexplored part of chemistry.

adversely or in need of improvement in the case described above Approaches that use as electrolytes pure ionic liquids or mixtures of these is the performance of the gas sensors in terms of both sensitivity and rise time, Selectivity and the robustness of the sensors.

task The present invention is an electrochemical gas sensor to provide, which has an improved performance, d. H. a higher selectivity, higher Sensitivity and higher robustness.

The Task is solved by an electrochemical gas sensor according to claim 1. Further preferred embodiments emerge from the dependent claims.

In In other words, the object is achieved by an electrochemical gas sensor solved, the ionic liquid as an electrolyte contains and is characterized in that the ionic Liquid organic and / or organometallic and / or having inorganic additives.

Of the electrochemical gas sensor contains at least 2 electrodes, which in electrical contact with the ionic liquid and what about separators or by distances are electrically isolated from each other. Were realized 2-, 3- or 4- or multi-electrode systems. Preferred are 2- and 3-electrode systems. In a preferred embodiment, a housing present, which has at least one opening, through which the gas to be detected enters the sensor. Another Embodiment is the imprint on a board or on flexible materials such as fabrics.

The Electrodes consist of a metal from the group of Cu, Ni, Ti, Pt, Ir, Au, Pd, Ag, Ru and Rh or mixtures or oxides of these Metals or carbon, the materials of the individual electrodes are the same or different.

The organic and / or organometallic and / or inorganic additives are contained in 0.05 to 15% by weight.

The Organic additives are preferably in 0.05 to 1.5% by weight contain. The inorganic additives are given in before 1 to 12% by weight. The organometallic additives are preferably contained in 0.05 to 1% by weight.

It could be successfully proven that the performance of gas sensors by said additions to the electrolyte, d. H. to increase the ionic liquid significantly both in terms of sensitivity and speed, Selectivity and the robustness of the sensors.

The ionic liquid contains at least one cation, which is selected from the group of imidazolium, Pyridinium, guanodinium, unsubstituted or with at least one Aryl and / or C1 to C4 alkyl group substituted, which itself unsubstituted or substituted with halogens, C1 to C4 alkyl groups, Hydroxyl or amino groups. Preferably, the ionic liquid at least imidazolium or pyridinium cations, unsubstituted or having at least one C1 to C4 alkyl group substituted.

With regard to the anions, the ionic liquid contains at least one anion from the group of halides, ie chloride, iodide, bromide or fluoride; Nitrates, nitrites, tetrafluoroborates, hexafluorophosphates, polyfluoroalkanesulfonates, bis (trifluoromethylsulfonyl) imides, alkyl sulfates, alkanesulfonates, acetates and the anions of Fluoroalkane acids.

Preferably is the at least one anion from the group of C1-C6-alkyl sulfates and C1-C6 alkanesulfonates. In this context it is particularly preferred if the ionic liquid at least one anion from the group of methyl, ethyl, butyl sulfate and methane, ethane, butanesulfonate.

In a most preferred embodiment is the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate.

The The present invention also includes mixtures of various ionic Liquids. A mixture of different ionic liquids Can be used to different polarities in the electrolyte. That can help certain additives to solve, but also be helpful to the water absorption to control the electrolyte. The hydrophilicity of the electrolyte has In addition, a decisive influence on the three-phase boundary at the measuring electrode (ME).

mixtures Various additives are also included. this concerns Mixtures of different additives of the same group, eg. B. mixtures of various organic additives. includes but are also mixtures of different additives, d. H. Mixtures of, for example, organic and inorganic additives. about Mixtures of various additives could cause cross-sensitivity patterns the sensors are adapted to specific needs.

The electrochemical gas sensor is used for the detection / measurement of gases from the group of acidic, basic, neutral, oxidizing or reducing gases and the halogen gases and vapors as well as the hydride gases. Preference is given to the use for the detection / measurement of gases from the group of F ₂ , Cl ₂ , Br ₂ , I ₂ , O ₂ , O ₃ , ClO ₂ , NH ₃ , SO ₂ , H ₂ S, CO, CO ₂ , NO, NO ₂ , H ₂ , HCl, HBr, HF, HCN, PH ₃ , AsH ₃ , B ₂ H ₆ , GeH ₄ and SiH ₄ .

in the With regard to the organic additives one can assume that their Effect on a stabilization of the reference potential, as well as the pH value is based. This shows advantages, especially with acidic gases.

The Organic additives are preferably selected from the group of imidazole, pyridine, pyrrole, pyrazole, pyrimidine, Guanine, unsubstituted or substituted with at least one C1- to C4 alkyl group; Uric acid, benzoic acid and Porphyrins and their derivatives. It is particularly preferred if the organic additives are selected from the Group of imidazole or pyrimidine, unsubstituted or substituted with at least one C1 to C4 alkyl group.

An electrochemical gas sensor in which the ionic liquid contains organic additives is preferably used for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, H ₂ , HCl, HCN and the hydride gases. Particularly preferred is the use for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, wherein the ionic liquid unsubstituted or substituted organic additives from the group of imidazole, pyridine, pyrrole, pyrazole, pyrimidine, guanine having at least one C1 to C4 alkyl group; Uric acid, benzoic acid and porphyrins and derivatives thereof. In a highly preferred embodiment, the electrochemical gas sensor is used for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, wherein the ionic liquid contains organic additives which are selected from the group of imidazole or pyrimidine, unsubstituted or substituted with at least one C1 to C4 alkyl group.

The Addition of 0.1 to 15% organic bases such as imidazole, Pyridine or guanine derivatives almost doubles the sensitivity the sensors on acid gases such. As hydrogen sulfide and sulfur dioxide. Also, the sensors run much more stable during the application with these gases. This is especially amazing against the background that all commercially available sensors on these gases acidic electrolytes such as As sulfuric acid use. The effect of the surcharges seems to rest on two principles. For one thing, you can have a clear one Shift of the reference potential with respect to the electrolytes Watch without surcharges, which is likely to stabilize the signal leads. On the other hand, the basic system seems act as a buffer and prevent the acidic gases in the electrolyte and thus, about a change the pH, in turn, a shift of the reference potential to generate.

The solutions act as second order conductors in gas sensors in the classical sense of a Clark cell (see 1 ) with noble metal catalysts or carbon as the measuring and counterelectrode (ME, GE) as a two-electrode system or with an additional reference electrode (BE) in three-electrode operation or with additional additional electrodes, if the sensor is equipped with a protective electrode or other measuring electrodes.

The Organic supplements are the ionic liquids added in the form of an aqueous solution or melted together with this. The type of addition depends from the water solubility of the aggregate, as well as from the Hydrophilicity of the ionic liquid.

If the effect of additives on the potentials measured between the measuring and reference electrodes of the gas sensors is compared with the effect on the sensor performance, differences result depending on the target gas under consideration. As an example, here a sensor cell is selected, which has the peculiarity of reacting to both sulfur dioxide and chlorine (Table 1). Table 1 Potentials [mV] (mean values) on SO ₂ ME vs. BE S [nA / ppm] (means) EMIM MeSO ₃ -93 2070 EMIM MeSO ₃ + imidazole -144 2890 EMIM MeSO ₃ + uric acid -182 2000

In the reaction to SO ₂ , it is noticeable that the addition of imidazole and uric acid leads to a negative of the sensor potential between the measuring and the reference electrode of the sensor. The magnitude of the reference potential does not appear to account for the increase in SO ₂ sensor sensitivity. In both cases, however, the addition leads to a stabilization of the sensor signal (see 2 and 3 ).

It is also interesting to observe the sensors over a longer period of time. For example, during the first two weeks, the sensors with imidazole as supplement are already significantly more sensitive than the comparative sensors without supplement during the maturing period of the sensors. This behavior is maintained until the end of the observation period ( 4 ). More importantly, the sensor curves also run stably, ie do not break during fumigation.

The organometallic additives are preferably selected from the group of organometallic porphyrins and their derivatives, wherein the organometallic porphyrins are preferably selected from the group of porphyrins having at least one meso or β-alkyl or aryl substituent and derivatives thereof. It is also preferred that the organometallic porphyrin derivatives are selected from the group of phthalocyanines having Mn ²⁺ , Cu ²⁺ , Fe ^{2+ / 3+} or Pb ²⁺ as metal cation.

An electrochemical gas sensor in which the ionic liquid contains organometallic additives is preferably used for the detection / measurement of gases from the group of CO, O ₂ , NO, NO ₂ and H ₂ . In particular, the use for the detection / measurement of gases from the group of CO, O ₂ , NO, NO ₂ and H _{2 is} preferred, wherein the ionic liquid contains organometallic additives from the group of organometallic porphyrins and their derivatives.

In a particularly preferred embodiment of the electrochemical gas sensor in which the ionic liquid contains organometallic additives, this is used for the detection / measurement of gases from the group of CO, NO, NO ₂ and H ₂ , wherein the ionic liquid organometallic additives from the group containing phthalocyanines with Mn ²⁺ , Cu ²⁺ , Fe ^{2+ / 3+} or Pb ²⁺ as metal cation.

With the addition of metal porphyrin derivatives, the selectivity of the sensors on certain gases such. B. increase carbon monoxide drastically. So far, this effect was only known in semiconductor gas sensors. The German patent DE 19956302 C2 describes a semiconductor gas sensor doped with various phthalocyanine derivatives. When the sensor is charged with NO or NO ₂ gas, a significantly reduced electron transmission energy is observed in the semiconductor material, and this leads to a sensor signal via a significant increase in the conductivity on the measuring electrode.

In the present case, the increase in the sensitivity of the sensors is not with an increase in the Conductivity to explain because it is graphite or precious metal electrodes and not to oxidic semiconductors.

A well-known problem in the field, for example, the strong cross-sensitivity from sensors with platinum electrodes to CO. As well as hydrogen sensors operated with platinum electrodes, it is in the classical Sensor technology de facto not possible Hydrogen next to To measure carbon monoxide. The use of metal porphorines can help to increase the selectivity of a sensor by that the specific solubility of gases in ionic Liquids is increased.

The Solutions, d. H. the ionic liquids, which containing organometallic additives act as conductors second order in gas sensors in the classical sense of a Clark cell, as already explained above, with noble metal catalysts or carbon as measuring and counterelectrode (ME, GE) as a two-electrode system or with an additional reference electrode (BE) in three-electrode mode or with additional additional electrodes, if the Sensor equipped with a protective electrode or other measuring electrodes. The organometallic additives can be ionic Liquids in the form of an aqueous solution be added or melted together with them or in to be suspended. The type of addition depends on the water solubility of the aggregate, of the hydrophilicity the ionic liquid and the expected secondary reaction from.

With respect to the electrochemical gas sensor in which the ionic liquid contains inorganic additives, these are preferably selected from the group of alkali halides and ammonium halides which are unsubstituted or substituted with C1 to C4 alkyl groups and the transition metal salts and lead salts. The transition metal salts or lead salts are preferably selected from the group of the salts of Mn ²⁺ , Mn ³⁺ , Cu ²⁺ , Ag ⁺ , Cr ³⁺ , Cr ⁶⁺ Fe ²⁺ , Fe ³⁺ and Pb ²⁺ . In particular, it is preferred that the inorganic additives are selected from the group of lithium bromide, lithium iodide, ammonium iodide, tetramethylammonium iodide, tetraethylammonium iodide, tetrapropylammonium iodide, tetrabutylammonium iodide, tetrabutylammonium bromide, manganese (II) chloride, manganese (II) sulfate and manganese (II) nitrate, chromium (III) chloride, alkali chromates, iron (II) chloride, iron (III) chloride and lead (II) nitrate.

An electrochemical gas sensor in which the ionic liquid contains inorganic additives is preferably used to detect / measure gases from the group of F ₂ , Cl ₂ , Br ₂ , I ₂ , O ₃ , ClO ₂ , NH ₃ , H ₂ , HCl , HCN and the hydride gases used.

Preferably, this sensor is used for the detection / measurement of gases from the group of CL ₂ , Br ₂ , O ₃ , ClO ₂ and NH ₃ , wherein the ionic liquid inorganic additives from the group of alkali halides and ammonium halides, which is unsubstituted or with C1- to C 4 alkyl groups and the transition metal salts and lead salts, preferably selected from the group of salts of Mn ²⁺ , Mn ³⁺ , Cu ²⁺ , Ag ⁺ , Cr ³⁺ , Cr ⁶⁺ , Fe ²⁺ , Fe Contains ³⁺ and Pb ²⁺ .

Particularly preferred is the use for the detection / measurement of gases from the group of Cl ₂ , Br ₂ , O ₃ , ClO ₂ and NH ₃ , wherein the ionic liquid inorganic additives from the group of lithium bromide, lithium iodide, tetrabutylammonium, tetrabutylammonium bromide, manganese ( II) chloride, manganese (II) sulfate and manganese (II) nitrate, chromium (III) chloride, alkali chromates, iron (II) chloride, iron (III) chloride and lead (II) nitrate.

The addition of alkali and ammonium halides, such as. B. LiI or NaBr, NR ₄ I (R = H, methyl, ethyl, butyl or mixtures thereof) in low percentages (0.05 to 15%) leads to a significant increase in the sensitivity of the sensors to halogen Gases and vapors. Higher alkali halides can be oxidized, for example, by Cl ₂ gas. The following sensor reaction is conceivable:
Partial analyte reaction with addition: Cl ₂ + 2Br ^- → Br ₂ + 2Cl ^-
Sensor reaction: Br ₂ + 2e ^- → 2Br ^-

In this case is a secondary reaction of Salts in the electrolyte. This can be seen from the fact that the reactions also take place when no active catalyst to implement the Target gases is available, but only one derivative made of carbon. Comparable (increase in sensitivity, high Selectivity) can also be exemplified by Observe ammonia sensors with the addition of manganese and copper salts. Transition metals On the other hand, complexes (eg: copper tetramine) with form the target gas and the potential shift in the Sensor generate a signal.

A major advantage of using inorganic additives is the selectivity of the sensor, as it is the Possibility to generate a specific detection reaction for the target gas. Thus, the combination of various additives can also generate cross-sensitivity patterns that would be inconceivable in classical sensor systems as well as in the use of pure ionic liquids.

The Solutions, d. H. the ionic liquids with inorganic additives, act as second order conductors in gas sensors in the classic sense of a Clark cell, as already explained above, with noble metal catalysts or carbon as measuring and counter electrode as a two-electrode system or with a additional reference electrode in three-electrode mode or with additional additional electrodes when looking at the sensor equipped with a protective electrode or other measuring electrodes. The inorganic additives become the ionic liquids added in the form of an aqueous solution or also melted together with these. The type of addition depends from the water solubility of the aggregate, from the hydrophilicity of ionic liquid and the expected secondary reaction from.

In the case of addition of inorganic additives to the base electrolyte of the Cl ₂ sensor, it can be seen that all sensors with additions (see 5 ) are more sensitive to the target gas than identical sensors without these additions (Table 2, Gold / Carbon (70:30) electrode).

Also, a better consistency of the sensors can be observed with each other. If one compares the sensitivity distributions of sensors with and without inorganic additives, it can be observed that chlorine sensors with LiBr have a significantly smaller dispersion of the sensitivities. This is impressively demonstrated by plotting the mean values of the standard deviations of both sensor types against each other (see 6 ). Table 2 Potentials [mV] ME vs. BE S [nA / ppm] on Cl ₂ EMIM MESO ₃ -93 1800 EMIM MESO ₃ + LiBr -130 2000 EMIM MESO ₃ + TBAI -56 2460 EMIM MESO ₃ + LiI -5 2260

considered one the potential differences, which in turn between the measuring and the reference electrode is measured is neither a correlation to the sensor sensitivities still to the stability of the Detect sensors.

replaces However, the gold / carbon electrode against an electrode pure carbon, one finds that the sensors are still work, d. H. Detecting chlorine gas. This is a reference that the reaction to chlorine is also a secondary reaction of the electrolyte with the gas and not just a reaction with the catalyst of the measuring electrode. In particular, because a Addition of LiCl leads to no significant measurement signal. It therefore requires specific inorganic additives to the to achieve the desired measuring effects.

Description of the figures

1 Construction diagram of a three-electrode electrochemical gas sensor;

2 Performance difference between ionic liquid sensors with and without organic aggregate;

3 Comparison of the sensor performance with imidazole as addition to the electrolyte or without surcharge;

4 Long-term observation of sensors with ionic liquid with and without imidazole addition;

5 Performance difference between sensors with and without inorganic aggregate;

6 Comparison of the standard deviations of the sensors with and without inorganic aggregate.

1 shows a gas sensor 1 that made a sensor housing 2 consists in which the measuring electrode 3 , Reference electrode 5 and counter electrode 6 are installed so that the measuring electrode 3 is connected via a gas-permeable membrane with the outside atmosphere. The electrodes are connected to each other via a separator 4 based on glass fibers or silicate structures, which are impregnated with said electrolyte, electrically conductively connected. In the sensor backspace provides a compensation volume 7 that atmospheric moisture can absorb water. The sensor is equipped with measuring electronics 8th connected, which amplifies the sensor current in the presence of target gas to a measurement signal.

2 shows the difference in performance between sensors with and without addition, whereby the signal stabilization takes place by the addition of uric acid to the electrolyte. Shown is the comparison between a pure ionic liquid (1-ethyl-3-methylimidazolium-methansulfonat) compared to the same ionic liquid with added uric acid when gassed with 4 ppm chlorine.

3 shows the comparison of the sensor performance with imidazole as a supplement to the electrolyte (1-ethyl-3-methylimidazolium methanesulfonat) or without a surcharge, with a significant increase in sensitivity and sensor stability can be seen. Fumigation takes place with 10 ppm SO ₂ gas.

4 shows graphically the observation of sensors with ionic liquid with and without imidazole addition over a longer period. The sensors with imidazole as additive are already significantly more sensitive during the first two weeks of the sensor's ripening period than the comparison sensors without surcharge. This behavior is maintained until the end of the observation period. The sensor curves are also stable, ie they do not break during fumigation.

5 shows the difference in performance between sensors with and without inorganic aggregate. Sensors with LiBr addition are more sensitive and the signals of individual sensors scatter less than sensors with the same ionic liquid without charge (IL = 1-ethyl-3-methylimidazolium methanesulfonat). Fumigation is carried out with 4 ppm chlorine gas.

6 shows a comparison of the standard deviations of the sensors with and without inorganic aggregate (LiBr) from the measurement on chlorine (4 ppm chlorine gas). With Additive, the sensitivities of the sensors are in a much narrower range than without additive.

1

gas sensor

2

sensor housing

3

measuring electrode under opening for gas inlet

4

separator impregnated with electrolyte on a fiberglass or silicate basis

5

reference electrode

6

counter electrode

7

compensating volume

8th

measuring electronics for amplifying the sensor signal

following the invention will be further explained by way of examples.

Examples

Example 1 - Cl ₂ sensor

The structure comprises a measuring electrode (ME) made of a mixture of gold (Au) and carbon (C) (30:70) and a counterelectrode (GE) = reference electrode (BE) made of platinum (Pt) (see 1 ). The electrodes are each applied to a gas-permeable PTFE membrane. Between the electrodes are electrolyte-impregnated glass fiber material separators to ensure electrical conductivity between the electrodes and to prevent other short circuits between the electrodes. (Deviating from 1 the sensor also works if the BE and GE are not parallel but stacked.) The electrolyte consists of 1-ethyl-3-methylimidazolium methanesulfonate (EMIM MeSO3) with one percent by weight of uric acid as an additive. The additive in this case was added in solid form to the EMIM MESO3 heated to 100 ° C. It gave a clear solution.

The fumigation was carried out with 4 ppm Cl ₂ in air at a flow of 200 l / h.

The result is graphically in 2 shown.

Example 2 - SO ₂ sensor

The sensor is constructed analogously to Example 1. In contrast to Example 1, the electrolyte EMIM MeSO ₃ contains 1% imidazole as supplement (instead of uric acid). The sensor also works very reliably, if instead of the ME from Au / C, a ME from an Au / Pd alloy or from Pt is used. Fumigation was carried out with 10 ppm SO ₂ gas in air at a flow of 200 l / h. The result is graphically in 3 shown.

Example 3 - Cl ₂ sensor

The sensor is constructed analogously to Example 1. In contrast to Example 1, the electrolyte EMIM MeSO ₃ contains 10% LiBr. This was stirred in crystalline into the heated to 100 ° C ionic liquid until a clear solution. The sensor also works when a ME of pure carbon is used instead of a ME made from a mixture of gold and carbon. The fumigation was carried out with 4 ppm Cl ₂ in air at a flow of 200 l / h. The results are graphically in the 4 and 5 shown.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 3328277 B [0002]
• US 4474648 B [0003]
• - DE 4238337 C2 [0003]
• - US 4169779 B [0005]
• - GB 2395564 B [0008, 0008]
• US 7060169 B2 [0008, 0008]
• - DE 102005020719 B3 [0008, 0008]
• DE 102004037312 A1 [0008]
• EP 1600768 A1 [0010]
• - US 6248224 B1 [0010]
• - DE 102006014715 B3 [0010]
• DE 19956302 C2 [0040]

Cited non-patent literature

• - Cai et al. Journal of East China Normal University (article number 1000-5641 (2001) 03-0057-04 [0007]
• P. Wasserscheid (Angew Chem 2000, 112, 3926-3945) [0011]
• - KR Seddon (Pure Appl. Chem. Vol. 72, No. 7, pp. 1391-1398, 2000) [0011]

Claims (32)

Electrochemical gas sensor with an ionic liquid as the electrolyte, characterized in that the ionic liquid organic and / or organometallic and / or inorganic additives. Electrochemical gas sensor according to claim 1, characterized characterized in that at least 2 electrodes are included, which in electrical contact with the ionic liquid and which over separations or by distances are electrically isolated from each other. Electrochemical gas sensor according to claim 2, characterized characterized in that the electrodes are made of a metal from the group of Cu, Ni, Ti, Pt, Ir, Au, Pd, Ag, Ru and Rh or mixtures or Oxides of these metals or carbon, wherein the materials the individual electrodes are the same or different. Electrochemical gas sensor according to one of the claims 1 to 3, characterized in that the organic and / or organometallic and / or inorganic additives in 0.05 to 15% by weight are included. Electrochemical gas sensor according to one of the claims 1 to 4, characterized in that the organic additives contained in 0.05 to 1.5% by weight. Electrochemical gas sensor according to one of the claims 1 to 5, characterized in that the inorganic additives in 1 to 12% by weight are included. Electrochemical gas sensor according to one of the claims 1 to 6, characterized in that the organometallic additives in 0.05 to 1% by weight. Electrochemical gas sensor according to one of the claims 1 to 7, characterized in that the ionic liquid contains at least one cation which is selected is from the group of imidazolium, pyridinium, guanodinium, unsubstituted or with at least one aryl and / or C1 to C4 alkyl group substituted, which itself is unsubstituted or substituted with halogens, C 1 - to C 4 -alkyl groups, hydroxyl or amino groups. Electrochemical gas sensor according to one of the claims 1 to 8, characterized in that the ionic liquid at least imidazolium or pyridinium cations, unsubstituted or substituted with at least one C 1 to C 4 alkyl group, contains. Electrochemical gas sensor according to one of the claims 1 to 9, characterized in that the ionic liquid at least one anion from the group of halides, nitrates, nitrites, Tetrafluoroborates, hexafluorophosphates, polyfluoroalkanesulfonates, bis (trifluoromethylsulfonyl) imides, Alkyl sulfates, alkanesulfonates, acetates and the anions of fluoroalkanoic acids contains. Electrochemical gas sensor according to one of the claims 1 to 10, characterized in that the ionic liquid contains at least one anion from the group of C1-C6 alkyl sulfates and C1-C6 alkanesulfonates. Electrochemical gas sensor according to one of the claims 1 to 11, characterized in that the ionic liquid at least one anion from the group of methyl, ethyl, butyl sulfate and methane, ethane, Buansulfonat contains. Electrochemical gas sensor according to one of the claims 1 to 12, characterized in that the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate. Electrochemical gas sensor according to one of the claims 1 to 13, characterized in that the organic additives are selected from the group of imidazole, pyridine, pyrrole, Pyrazole, pyrimidine, guanine, unsubstituted or substituted with at least one C1 to C4 alkyl group; Uric acid, benzoic acid and Porphyrins and their derivatives. Electrochemical gas sensor according to one of claims 1 to 14, characterized in that the organic additives are selected from the group of imidazole or pyrimidine, unsubstituted or substituted tuiert with at least one C1 to C4 alkyl group. Electrochemical gas sensor according to one of the claims 1 to 15, characterized in that the organometallic additives are selected from the group of organometallic porphyrins and their derivatives. Electrochemical gas sensor according to one of the claims 1 to 16, characterized in that the organometallic porphyrins are selected from the group of porphyrins with at least a meso or β-alkyl or aryl substituent and their Derivatives. Electrochemical gas sensor according to one of claims 1 to 17, characterized in that the organometallic porphyrin derivatives are selected from the group of phthalocyanines with Mn ²⁺ , Cu ²⁺ , Fe ^{2 + / 3 +} or Pb ²⁺ as metal cation. Electrochemical gas sensor according to one of the claims 1 to 18, characterized in that the inorganic additives are selected from the group of alkali halides and Ammonium halides which are unsubstituted or with C1 to C4 alkyl groups and the transition metal salts and lead salts. Electrochemical gas sensor according to one of claims 1 to 19, characterized in that the transition metal salts or lead salts are selected from the group of salts of Mn ²⁺ , Mn ³⁺ , Cu ²⁺ , Ag ⁺ , Cr ³⁺ , Cr ⁶⁺ , Fe ²⁺ , Fe ³⁺ and Pb ²⁺ . Electrochemical gas sensor according to one of the claims 1 to 20, characterized in that the inorganic additives are selected from the group of lithium bromide, lithium iodide, Ammonium iodide, tetramethylammonium iodide, tetraethylammonium iodide, Tetrapropylammonium iodide, tetrabutylammonium iodide, tetrabutylammonium bromide, Manganese (II) chloride, manganese (II) sulfate, manganese (II) nitrate, chromium (III) chloride, Alkalichromates, iron (II) chloride, ferric chloride and lead (II) nitrate. Use of an electrochemical gas sensor according to one of claims 1 to 21 for the detection / measurement of Gases from the group of acidic, basic, neutral, oxidizing or reducing gases and halogen gases and vapors and the hydride gases. Use of an electrochemical gas sensor according to claim 22 for the detection / measurement of gases from the group of F ₂ , Cl ₂ , Br ₂ , I ₂ , O ₂ , O ₃ , ClO ₂ , NH ₃ , SO ₂ , H ₂ S, CO, CO ₂ , NO, NO ₂ , H ₂ , HCl, HBr, HF, HCN, PH ₃ , AsH ₃ , B ₂ H ₆ , GeH ₄ and SiH ₄ . Use of an electrochemical gas sensor according to any one of claims 22 or 23 for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, H ₂ , HCl, HCN and the hydride gases, wherein the ionic liquid contains organic additives. Use of an electrochemical gas sensor according to any one of claims 22 to 24 for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, wherein the ionic liquid organic additives from the group of imidazole, pyridine, pyrrole, pyrazole, pyrimidine , Guanine, unsubstituted or substituted with at least one C1 to C4 alkyl group; Uric acid, benzoic acid and porphyrins and derivatives thereof. Use of an electrochemical gas sensor according to any one of claims 22 to 25 for the detection / measurement of gases from the group of NH ₃ , SO ₂ , H ₂ S, wherein the ionic liquid organic additives selected from the group of imidazole or pyrimidine, unsubstituted or substituted with at least one C1 to C4 alkyl group. Use of an electrochemical gas sensor according to any one of claims 22 or 23 for the detection / measurement of gases from the group of F ₂ , Cl ₂ , Br ₂ , I ₂ , O ₃ , ClO ₂ , NH ₃ , H ₂ , HCl, HCN and the hydride gases, the ionic liquid containing inorganic additives. Use of an electrochemical gas sensor according to any one of claims 22 to 23 or 27 for the detection / measurement of gases from the group of CL ₂ , Br ₂ , O ₃ , ClO ₂ and NH ₃ , wherein the ionic liquid inorganic additives from the group of alkali halides and Ammonium halides which are unsubstituted or substituted by C1 to C4 alkyl groups and the transition metal salts and lead salts, vorzugswei selected from the group of salts of Mn ²⁺ , Mn ³⁺ , Cu ²⁺ Ag ⁺ , Cr ³⁺ , Cr ⁶⁺ , Fe ²⁺ , Fe ³⁺ and Pb ²⁺ . Use of an electrochemical gas sensor according to any one of claims 22 to 23 or 27 to 28 for the detection / measurement of gases from the group of Cl ₂ , Br ₂ , O ₃ , ClO ₂ and NH ₃ , wherein the ionic liquid inorganic additives from the group of Lithium bromide, lithium iodide, tetrabutylammonium iodide, tetrabutylammonium bromide, manganese (II) chloride, manganese (II) sulfate, manganese (II) nitrate, chromium (III) chloride, alkali chromates, ferrous chloride, ferric chloride and lead (II) contains nitrate. Use of an electrochemical gas sensor according to claim 22 to 23 for the detection / measurement of gases from the group of CO, O ₂ , NO, NO ₂ and H ₂ , wherein the ionic liquid contains organometallic additives. Use of an electrochemical gas sensor according to any one of claims 22 to 23 or 30 for the detection / measurement of gases from the group of CO, O ₂ , NO, NO ₂ and H ₂ , wherein the ionic liquid organometallic additions from the group of organometallic porphyrins and their Contains derivatives. Use of an electrochemical gas sensor according to any one of claims 22 to 23 or 30 to 31 for the detection / measurement of gases from the group of CO, NO, NO ₂ and H ₂ , wherein the ionic liquid organometallic additives from the group of phthalocyanines with Mn ²⁺ , Cu ²⁺ , Fe ^{2 + / 3 +} or Pb ²⁺ as a metal cation.