Sensor for detecting a gaseous analyte

Abstract

A sensor and a method for using the sensor are disclosed. The sensor includes a conductive region electrically connected to two electrodes, the conductive region including single-walled carbon nanotubes, nano-sized particles of metal dichalcogenides, and a mercaptoimidazole-based metal-ligand complex. The sensor can be used to detect volatile compounds having double or triple bonds.

Description

[0001] Background

[0002] Exemplary embodiments relate to techniques of sensor compositions based on metal-ligand complexes.

[0003] Volatile compounds having double bonds form an important group of compounds for detection. In particular, volatile olefins (such as ethylene) are quite important analytes. In particular, the detection of ethylene is important for industries related to production and agriculture. However, due to its small size and limited chemical functionality, ethylene is a challenging chemical analyte to detect. Detection methods that are more effective and sensitive than those currently available are needed.

[0004] Brief Description

[0005] A sensor is disclosed that includes a conductive region in electrical communication with two electrodes, the conductive region including single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a thiolimidazole-based metal-ligand complex.

[0006] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the nanosized particles of the metal dichalcogenide include MoS 2 , WS 2 , MoSe 2 , WSe 2 , MoTe 2 , WTe 2 and combinations thereof.

[0007] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex includes more than one thiolimidazole group.

[0008] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex includes three thiolimidazole groups.

[0009] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex includes a pyrazolyl or indolyl group in addition to the thiolimidazole group.

[0010] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex includes Cu(I), Ag(I), or Au(I).

[0011] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex is a complex of formula (II):

[0012]

[0013] Wherein, R 1 and R 2 can each be hydrogen or a group having one or more carbons in each case.

[0014] Also disclosed is a method for sensing volatile compounds having a double bond or a triple bond, the method comprising exposing a sensor to a sample, the sensor comprising a conductive region in electrical communication with two electrodes, the conductive region comprising single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a mercaptoimidazole metal-ligand complex, and measuring the electrical properties at the electrodes.

[0015] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the electrical property is conductivity.

[0016] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the electrical property is resistivity.

[0017] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the method further comprises comparing the electrical property value obtained by measurement with a calibration curve to determine the amount of volatile compounds having a double bond or a triple bond present in the sample.

[0018] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the volatile compound having a double bond or a triple bond is ethylene.

[0019] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the nanosized particles of the metal dichalcogenide comprise MoS 2 、WS 2 、MoSe 2 、WSe 2 、MoTe 2 、WTe 2 and combinations thereof.

[0020] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the mercaptoimidazole metal-ligand complex comprises more than one mercaptoimidazole group.

[0021] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the mercaptoimidazole metal-ligand complex comprises three mercaptoimidazole groups.

[0022] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex further includes a pyrazolyl group or an indolyl group in addition to the thiolimidazole group.

[0023] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex includes Cu(I), Ag(I), or Au(I).

[0024] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the thiolimidazole-based metal-ligand complex is a complex of formula (II):

[0025]

[0026] wherein R 1 and R 2 may each independently be hydrogen or a group having one or more carbons.

[0027] In another aspect, a method of fabricating a sensor includes forming a conductive region including single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a thiolimidazole-based metal-ligand complex, and placing the conductive region in electrical communication with two electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following description should not be regarded as limiting in any way. Referring to the drawings, like elements are numbered alike:

[0030] Figure 1 is a graph of the electrode signal plotted against the gas concentration.

[0031] DETAILED DESCRIPTION

[0032] Referring to the drawings, by way of example and not limitation, a detailed description of one or more embodiments of the disclosed apparatus and method is presented herein.

[0033] Volatile compounds having double or triple bonds are an important group of compounds for detection and monitoring. As used herein, the term volatile refers to compounds that are in the gas phase at standard temperature and pressure. Exemplary compounds include NO 2 , CO 2 , CO, and olefins such as C 2 H 4(Ethylene). As a hormone responsible for initiating fruit ripening and other processes in plant development, ethylene is an analyte of considerable importance to industries related to production and agriculture. Due to its small size and limited chemical functionality, ethylene and other volatile olefins are challenging chemicals to detect. Sensors and methods are disclosed herein that are capable of detecting volatile compounds with double bonds, such as ethylene and other volatile olefins, at levels as low as 100 parts per billion (ppb).

[0034] The sensor includes a conductive region that is in electrical communication with at least two electrodes. The conductive region includes single-walled carbon nanotubes, nanosized particles of metal dichalcogenides, and thiol-imidazole-based metal-ligand complexes.

[0035] Single-walled carbon nanotubes are known materials and are commercially available. Exemplary materials include single-walled nanotubes available from NanoIntegris, US Research Nanomaterials, Inc., Millipore Sigma (formerly SigmaAldrich), and NanoLab, Inc.

[0036] Metal dichalcogenides include transition metal dichalcogenides, which are compounds formed from Group 6B metals and chalcogenides (S, Se, and Te). Exemplary metal dichalcogenides include MoS 2 、WS 2 、MoSe 2 、WSe 2 、MoTe 2 、WTe 2 and combinations thereof. The metal dichalcogenides are in the form of nanosized particles. "Nanosized" when applied to metal dichalcogenides refers to the fact that the thickness of the material is less than or equal to 100 nanometers. Metal dichalcogenides are typically available in the form of flakes with a thickness of 100 nanometers or less, but other physical forms are not excluded, such as few-layer or single-layer materials, provided that the physical form has at least one linear dimension less than or equal to 100 nanometers.

[0037] Thiol-imidazole-based metal-ligand complexes are polydentate coordination complexes containing one or more thiol-imidazole groups. The arms (groups on the boron atom) of the polydentate ligand can be the same (homodentate) or different (heterodentate). For example, one arm can contain a thiol-imidazole group and the second arm can contain a pyrazolyl or indolyl group. It is also contemplated that the polydentate ligand can contain more than one thiol-imidazole group or a combination of thiol-imidazole groups and pyrazolyl or indolyl groups or both. The thiol-imidazole-based metal-ligand complex can have the formula (I)

[0038]

[0039] wherein, R1 and R 2 In each case may be hydrogen or a group having one or more carbons. In some embodiments, R 1 and R 2 In each case may be hydrogen or an alkyl group having 1 - 5 carbons. L in formula (I) may be a pyrazolyl group, a mercaptoimidazolyl group, or an indolyl group. When L is a mercaptoimidazolyl group, the multidentate metal - ligand complex can be described as homoleptic. When L is a group other than a mercaptoimidazolyl group, the metal - ligand complex can be described as heteroleptic. The presence of VOC in formula (I) is to show the putative interaction with a volatile compound having a π - bond. Without being bound by theory, it is believed that the π - bond of the volatile compound coordinates to the vacant ligand sites on the metal - ligand complex. The coordination changes the electronic configuration of the complex and can affect the electrical properties of the combination of the metal - ligand complex, the nanosized particles of metal dichalcogenide, and the metal nanowires. In the case of a metal complex having formula (II) shown below, when the metal complex binds to ethylene, the resistivity of the combination of the metal - ligand complex, the nanosized particles of metal dichalcogenide, and the metal nanowires increases.

[0040] A more specific example of a mercaptoimidazolyl metal complex is shown in formula (II).

[0041]

[0042] In formula (II), there are three mercaptoimidazolyl groups. R 1 and R 2 Are as defined in formula (I).

[0043] The metal in the mercaptoimidazolyl metal complex may include Group 11 elements such as Cu(I), Ag(I), and Au(I).

[0044] Single - walled carbon nanotubes and nanosized particles of metal dichalcogenide are applied to a substrate. The substrate can be a flexible polymer film or other suitable material. Exemplary flexible polymer films include polyethylene terephthalate, polyethylene, polypropylene, polyamide, and polyvinyl chloride. Before applying the single - walled carbon nanotubes and the nanosized particles of metal chalcogenide, electrodes can be deposited on the substrate. The single - walled carbon nanotubes and the nanosized particles of metal chalcogenide can be applied by spray deposition. Table 1 provides examples of formulations that have been used to prepare working sensors. These materials are co - deposited or sequentially deposited. After applying the single - walled carbon nanotubes and the nanosized particles of metal dichalcogenide to the substrate, the mercaptoimidazolyl metal - ligand complex is deposited on top of the single - walled carbon nanotubes and the nanosized particles of metal dichalcogenide. The mercaptoimidazolyl metal - ligand complex can be applied by drop - casting, dip - coating, spraying, or electrospraying. Then the layered material is dried and ready for use.

[0045] Table 1

[0046] <![CDATA[H 2 O]]> 91 wt% iPrOH 9 wt% <![CDATA[MoS 2 > 1.9 ppm SWCNT 2.5 ppm Sodium deoxycholate (surfactant) < 1 wt%

[0047] A method for sensing volatile compounds having double or triple bonds includes exposing the sensor as described above to a sample and measuring the electrical properties at the electrodes. The electrical properties may be conductivity or resistivity. The method may also include comparing the obtained electrical property values with a calibration curve to determine the amount of volatile compounds present in the sample.

[0048] Figure 1 Showing data obtained using a combination of nano-sized particles of MoS 2 and single-walled carbon nanotubes as the underlying layer. The underlying layer is coated with a thiol imidazole-based metal-ligand complex represented by formula (II). The peaks are due to ethylene absorption (the samples for ethylene exposure contain ethylene in an amount from 10 ppm to 0.1 ppm).

[0049] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0050] Although the present disclosure has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for its elements without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A sensor, the sensor comprising a conductive region electrically connected to two electrodes, the conductive region comprising single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a mercaptoimidazole metal-ligand complex, wherein the nanosized particles of the metal dichalcogenide comprise MoS 2 , and wherein the mercaptoimidazole metal-ligand complex is a homoleptic complex of formula (II): Among them, R 1 and R 2 is hydrogen or an alkyl group having 1 to 5 carbons in each case.

2. A method for sensing volatile compounds having double or triple bonds, the method comprising exposing a sensor to a sample, the sensor comprising a conductive region in electrical communication with two electrodes, the conductive region comprising single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a thiolimidazole metal-ligand complex, and measuring an electrical property at the electrodes, wherein the nanosized particles of the metal dichalcogenide comprise MoS 2 , and wherein the thiolimidazole metal-ligand complex is a homoleptic complex of formula (II): Among them, R 1 and R 2 is hydrogen or an alkyl group having 1 to 5 carbons in each case.

3. The method according to claim 2, wherein the electrical property is conductivity.

4. The method according to claim 2, wherein the electrical property is resistivity.

5. The method according to any one of claims 2-4, the method further comprising comparing the value of the electrical property obtained by measurement with a calibration curve to determine the amount of volatile compounds having double bonds or triple bonds present in the sample.

6. The method according to claim 5, wherein the volatile compound having double bonds or triple bonds is ethylene.

7. A method for preparing a sensor, the method comprising forming a conductive region, the conductive region comprising single-walled carbon nanotubes, nanosized particles of a metal dichalcogenide, and a mercaptoimidazole metal-ligand complex, and placing the conductive region in electrical communication with two electrodes, wherein the nanosized particles of the metal dichalcogenide comprise MoS 2 , and wherein the mercaptoimidazole metal-ligand complex is a homoleptic complex of formula (II): Among them, R 1 and R 2 is hydrogen or an alkyl group having 1 to 5 carbons in each case.

Images