Ifsttar PhD subject

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Title : Functionnalized nanomaterials for gas sensing

Main host Laboratory - Referent Advisor   -

Director of the main host Laboratory   -

PhD Speciality nanotechnologie, matériaux

Axis of the performance contract 3 - COP2017 - Planning and protecting regions

Main location Marne-la-Vallée

Doctoral affiliation UNIVERSITE PARIS - SACLAY

PhD school Interfaces

Planned PhD supervisor YASSAR Abderrahim  -  Ecole Polytechnique  -  CA/DER/LAB/PICM

Planned financing Contrat doctoral  - Ifsttar

Abstract

Environmental monitoring is required to protect the public and the environment from toxic contaminants and pathogens that can be released into a variety of media including air, soil, and water. Moreover, the global environmental monitoring market is poised to grow at a CAGR of 7.5% during 2015-2020, and is expected to reach a value of ~$20.5 Billion in 2020 [1]. As an example: The air segment in the environmental sensing and monitoring market is anticipated to reach USD ~7.7 billion by the end of 2019. This augmentation is driven by different factors such as the massive scale of urbanisation and population growth, development of policies to reduce water, soil and air pollutants and the increase of monitoring environmental stations. In this framework, the development of low-cost, easy-to-use, miniaturized, portable and long-term monitoring of environmental sensors allowing accurate measurements of air pollutants is needed.
Gas sensors based on metal oxides have raised great interest in many areas, such as environmental monitoring, domestic safety, public security, as well as for automotive applications... However, large scale use and effective monitoring of environmental pollution require the development of cheap, small, low power consumption and reliable solid state gas sensors in the coming years [2]. Nanomaterials such as carbon nanotubes, graphene and transition metal dichalcogenides (TMDs), MoS2 or WS2, MoSe2 as well as black phosphorus (also known as phosphorene) are one of the best promising candidates for the future development of nanosensors applications [3-4]. This originates from their high surface area (dense number of adsorption sites), high electrical conductivities and low electrical noise (a small change in carrier concentration induced by gas exposure induces significant changes in electrical conductivity), as well as appropriate band gap opening (that can be tuned by the number of the layers in the case of TMDs) [5-7]. In addition, carbon nanotubes and 2D materials can be operated at room temperature, which is impossible in metal oxide semiconductors [8].
The goal of this PhD proposal is to develop a reliable and selective new generation of gas sensors based on nanomaterials: carbon nanotubes and 2D materials, that will be used as active layer to detect and quantify selectively the air pollutants (NOx and CO for example) in various environments.
Gas sensors based on nanomaterials (carbon nanotubes or 2D materials) have demonstrated excellent sensing characteristics in particular a high sensitivity (a few ppb), a fast response (in a few seconds) and a high stability. However, sensors based on nanomaterials do not show any selectivity to specific gas. They rather tend to measure the variation of the global gas content. In most real life applications, especially in urban air, it is not acceptable, as pollutants are numerous with concentrations varying widely in space and time. Various strategies have been studied to enhance the selectivity of nanomaterials to specific gases by fingerprinting techniques and functionalization by appropriate chemical functions. To improve the selectivity, we propose a new approach based on the non-covalent functionalization of the active layer of the sensor using organometallic complexes (such as BiSalophen (MBS), DipyrinPhenol (MDP)) or porphyrines. The non-covalent functionalization allows reliable immobilization of organometallic complexes on the surface of nanomaterials without damaging its electrical performance and ensuring highly sensitivity and specific selectivity for gas. The nature of the ligand cavity allows the coordination of different metal ions, thus enabling the sensing of different gas molecules and enhancing selectivity. Recently, we demonstrated that these complexes assembly in a non-covalent way on the surface of carbon nanotubes and graphene (with extended π system) [9-11]. Evidence of a charge transfer between metal and nanomaterials (graphene and nanotubes) were reported [9-11].
The objective of this thesis is to develop a gas sensor based on nanomaterials to detect NOX. First, we will study the functionalization of different nanomaterials such as carbon nanotubes and 2D materials with different molecules (BiSalophen, DipyrinPhenol, ou porphyrines). Then, the efficiency of the grafting will be characterized by different techniques such as Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and atomic force microscope (AFM). The charge transfer between the molecules and nanomaterials will be confirmed by the study of the electrical characteristics of nanomaterials. In this thesis, two types of devices will be fabricated (transistor and/or resistive devices). Finally, we will study the sensitivity and the selectivity of the devices under NOx. In order to evaluate the selectivity of the sensor, we will test the devices exposed to the targeted gas mixed with the interferential gases. After the validation of the tests lab, we will study the performances of the devices in the real world conditions, using equipex “Sense City” facility [12].

Bibliography:
[1] http://www.marketsandmarkets.com
[2] E. Bakker, Electrochemical Sensors. Analytical Chemistry 2004. 76(12) (2004) 3285–98.
[3] M. Meyyappan, Carbon Nanotubes: Science and Applications, CRC Press, Boca Raton, Fla, USA.
[4] S. Cui et al. Nature Communications, 6, DOI: 10.1038/ncomms9632.
[5] Q. H. Wang et al. Nat. Nanotechnol., 7 (2012) 699.
[6] H. Li et al. Nat. Mater., 15 (2016) 48.
[7] G. Lu et al. J. Chen , Nanotechnology, 20 (2009) 445502.
[8] H. Y. Jeong et al. Appl. Phys. Lett., 96 (2010) 213105.
[9] G. Magadur et al. Chemical Communications, 48 (2012) 9071-9073.
[10] G. Magadur et al. J. Am. Chem. Soc., 134 (18) (2012) 7896–7901.
[11] Thesis of Heechul Woo, 29 September 2016.
[12] http://sense-city.ifsttar.fr/.

Keywords : sensors, nanomaterials, unctionalization

Main host Laboratory - Referent Advisor	-
Director of the main host Laboratory	-
PhD Speciality	nanotechnologie, matériaux
Axis of the performance contract	3 - COP2017 - Planning and protecting regions
Main location	Marne-la-Vallée
Doctoral affiliation	UNIVERSITE PARIS - SACLAY
PhD school	Interfaces
Planned PhD supervisor	YASSAR Abderrahim - Ecole Polytechnique - CA/DER/LAB/PICM
Planned financing	Contrat doctoral - Ifsttar
Abstract Environmental monitoring is required to protect the public and the environment from toxic contaminants and pathogens that can be released into a variety of media including air, soil, and water. Moreover, the global environmental monitoring market is poised to grow at a CAGR of 7.5% during 2015-2020, and is expected to reach a value of ~$20.5 Billion in 2020 [1]. As an example: The air segment in the environmental sensing and monitoring market is anticipated to reach USD ~7.7 billion by the end of 2019. This augmentation is driven by different factors such as the massive scale of urbanisation and population growth, development of policies to reduce water, soil and air pollutants and the increase of monitoring environmental stations. In this framework, the development of low-cost, easy-to-use, miniaturized, portable and long-term monitoring of environmental sensors allowing accurate measurements of air pollutants is needed. Gas sensors based on metal oxides have raised great interest in many areas, such as environmental monitoring, domestic safety, public security, as well as for automotive applications... However, large scale use and effective monitoring of environmental pollution require the development of cheap, small, low power consumption and reliable solid state gas sensors in the coming years [2]. Nanomaterials such as carbon nanotubes, graphene and transition metal dichalcogenides (TMDs), MoS2 or WS2, MoSe2 as well as black phosphorus (also known as phosphorene) are one of the best promising candidates for the future development of nanosensors applications [3-4]. This originates from their high surface area (dense number of adsorption sites), high electrical conductivities and low electrical noise (a small change in carrier concentration induced by gas exposure induces significant changes in electrical conductivity), as well as appropriate band gap opening (that can be tuned by the number of the layers in the case of TMDs) [5-7]. In addition, carbon nanotubes and 2D materials can be operated at room temperature, which is impossible in metal oxide semiconductors [8]. The goal of this PhD proposal is to develop a reliable and selective new generation of gas sensors based on nanomaterials: carbon nanotubes and 2D materials, that will be used as active layer to detect and quantify selectively the air pollutants (NOx and CO for example) in various environments. Gas sensors based on nanomaterials (carbon nanotubes or 2D materials) have demonstrated excellent sensing characteristics in particular a high sensitivity (a few ppb), a fast response (in a few seconds) and a high stability. However, sensors based on nanomaterials do not show any selectivity to specific gas. They rather tend to measure the variation of the global gas content. In most real life applications, especially in urban air, it is not acceptable, as pollutants are numerous with concentrations varying widely in space and time. Various strategies have been studied to enhance the selectivity of nanomaterials to specific gases by fingerprinting techniques and functionalization by appropriate chemical functions. To improve the selectivity, we propose a new approach based on the non-covalent functionalization of the active layer of the sensor using organometallic complexes (such as BiSalophen (MBS), DipyrinPhenol (MDP)) or porphyrines. The non-covalent functionalization allows reliable immobilization of organometallic complexes on the surface of nanomaterials without damaging its electrical performance and ensuring highly sensitivity and specific selectivity for gas. The nature of the ligand cavity allows the coordination of different metal ions, thus enabling the sensing of different gas molecules and enhancing selectivity. Recently, we demonstrated that these complexes assembly in a non-covalent way on the surface of carbon nanotubes and graphene (with extended π system) [9-11]. Evidence of a charge transfer between metal and nanomaterials (graphene and nanotubes) were reported [9-11]. The objective of this thesis is to develop a gas sensor based on nanomaterials to detect NOX. First, we will study the functionalization of different nanomaterials such as carbon nanotubes and 2D materials with different molecules (BiSalophen, DipyrinPhenol, ou porphyrines). Then, the efficiency of the grafting will be characterized by different techniques such as Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and atomic force microscope (AFM). The charge transfer between the molecules and nanomaterials will be confirmed by the study of the electrical characteristics of nanomaterials. In this thesis, two types of devices will be fabricated (transistor and/or resistive devices). Finally, we will study the sensitivity and the selectivity of the devices under NOx. In order to evaluate the selectivity of the sensor, we will test the devices exposed to the targeted gas mixed with the interferential gases. After the validation of the tests lab, we will study the performances of the devices in the real world conditions, using equipex “Sense City” facility [12]. Bibliography: [1] http://www.marketsandmarkets.com [2] E. Bakker, Electrochemical Sensors. Analytical Chemistry 2004. 76(12) (2004) 3285–98. [3] M. Meyyappan, Carbon Nanotubes: Science and Applications, CRC Press, Boca Raton, Fla, USA. [4] S. Cui et al. Nature Communications, 6, DOI: 10.1038/ncomms9632. [5] Q. H. Wang et al. Nat. Nanotechnol., 7 (2012) 699. [6] H. Li et al. Nat. Mater., 15 (2016) 48. [7] G. Lu et al. J. Chen , Nanotechnology, 20 (2009) 445502. [8] H. Y. Jeong et al. Appl. Phys. Lett., 96 (2010) 213105. [9] G. Magadur et al. Chemical Communications, 48 (2012) 9071-9073. [10] G. Magadur et al. J. Am. Chem. Soc., 134 (18) (2012) 7896–7901. [11] Thesis of Heechul Woo, 29 September 2016. [12] http://sense-city.ifsttar.fr/.
Keywords :	sensors, nanomaterials, unctionalization

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