Electrodes Modification Based on Metal-Free Phthalocyanine: Example of Electrochemical Sensors for the Detection of Acetic Acid

Electroanalytical properties of tetra-tert-butyl phthalocyanine (PcH 2 -tBu) modified electrodes are studied by cyclic voltammetry (CV). The modified electrodes are obtained by CV deposition techniques on gold (Au) and glassy carbon (C) screenprinted electrodes (SPEs) and used for the electrochemical detection of acetic acid (AA). Based on the CV experiments, the electrodeposition mechanism is detailed. The modified PcH 2 -tBu electrodes reveal one oxidation and one reduction peak within the potential window of the working electrodes. In the presence of the analyte (acetic acid), the modified electrodes show sensitivity in the range of 10 mM to 400 mM. For the PcH 2 -tBu modified Au electrode, a limit of detection (LOD) of 5.89 mM (based on the +0.06 V peak) was obtained while for the PcH 2 -tBu modified C electrode a LOD of 17.76 mM (based on the +0.07 V peak) was achieved. A signal decay of 17%, based on 20 experiments, is obtained when gold is used as working electrode. If carbon is used as working electrode a value of 7% is attained. A signal decay is observed after more than 50 cycles of experiments and is more pronounced when higher concentrations of acetic acid are used. A mechanism of sensing is proposed at the end

On-board phthalocyanine gas sensor microsystem dedicated to the monitoring of oxidising gases level in passenger compartments

International audienceThe monitoring of in-vehicle pollutant concentrations by means of an on-board molecular semiconductor gas sensor microsystem is described in this paper. The main objective is to measure in real time with a high level of accuracy the variations of oxidising gases concentration in bus passenger compartments to inform travellers or commuters and to evaluate the assessment of bus drivers' exposure. A self-contained gas sensor microsystem of which the sensitive element is constituted by a thin layer of copper phthalocyanine has been developed, validated at laboratory under controlled experimental conditions and then implemented in a bus of the urban network of Clermont-Ferrand, France. Preliminary in-car measurements realized with commercial analyzers show that nitrogen dioxide is the major oxidising gas present on urban roads and so is considered as the target gas in this study. Tests realized under artificially polluted atmosphere show the high performances obtained with our microsystem, such as high resolution, low threshold, good reproducibility, satisfying concentration range and real time detection. The calibration curve has been determined at laboratory by experiments made under low NO2 concentrations in the range of those measured in urban atmosphere. The relation between sensor microsystem response and gas concentration is established with accuracy. The validation of our microsystem is illustrated by measurements realized under real conditions, i.e. in an urban bus. It shows that NO2 concentration variations are mainly correlated with the nature of roads and that rates of pollutant measured in traffic are always greater than those measured by the nearest stations of the air quality control network

An original methodology of measurements for ozone detection in a mix (O3,NO2) with pseudo-schottky Pd-InP gas sensor

This article deals with Pseudo-Schottky diode consists of InP-p gas sensor with metallized layer of Palladium. In a first time, original results of carbon monoxide action (CO) on metallized layer are shown. It can be seen that Pseudo-Shottky diode submission to CO avoided the degradation of gas sensor parameters by ozone. Then an original methodology of measurements that takes avantages of gas sensor selectivity towards ozone, to follow in real time variations of concentration, is described

La fonctionnalisation des matériaux carbonés comme moyen pour le développement de capteurs dédiés à la détection de polluants atmosphériques.

International audienceAvec les avancés des nanotechnologies, les matériaux 1D ou 2D sont de plus mis en avant grâce à leurs propriétés exceptionnelles inhérentes à leurs faibles dimensions. Parmi ces matériaux, les nanomatériaux carbonés (nanotubes de carbone, graphène etc.) occupent une place très importante, du fait de leurs propriétés mécaniques, optiques et électroniques exceptionnelles mais surtout grâce à leur grande surface spécifique. Cette dernière propriété explique le choix de ces nanomatériaux comme matériaux sensibles dans le domaine des capteurs. En plus l’environnement chimique de leur surface est très sensible à l’adsorption de corps étrangers ou à un stimulus. Cette réactivité combinée à leur grande capacité d’adsorption leurs confèrent des propriétés essentielles dans le domaine des capteurs. Cependant cette grande sensibilité aux gaz est souvent un problème dans le domaine des capteurs puisqu’elle se traduit en une réactivité non spécifiée et de façon simultané à d’autres gaz en même temps. C’est dans ce contexte que ces nanomatériaux sont fonctionnalisés pour leur apporter une réactivité spécifique. Les molécules ou agents fonctionnels sont ainsi associés aux matrices nanocarbonées pour accéder à des performances ou des propriétés que les entités individuelles ne permettent pas d’avoir. C’est ainsi que des nanoparticules, des molécules, des macrocycles, des oxydes métalliques etc. sont greffés où incorporer à ces matrices nanocarbonées pour des applications variées. Les macrocycles tels que les phtalocyanines ou porphyrines du fait de leur nuages d’électrons fortement délocalisées sont de potentiels candidats pour des applications capteur. En effet ces macrocycles peuvent être ainsi utilisés pour rendre des matériaux comme graphène ou les nanotubes de carbones plus sensibles à la détection de gaz. Ces macrocycles présentent l’avantage d’être adaptés pour la fonctionnalisation aussi bien par voie covalente que non covalente et en plus ils possèdent eux-mêmes des propriétés physicochimiques essentielles pour des applications envisagées notamment dans le domaine des capteurs. De plus ils peuvent être déposé en films minces par plusieurs techniques chimique ou physique (par évaporation thermique par exemple). Ils peuvent par exemple être mise en avant pour la détection d’espèces polluantes comme les BTX (Benzène, toluène, xylènes) du fait de leur nuage électronique. Dans cette présentation, je parlerais des choix des matériaux, du type de fonctionnalisation et des caractérisations physico-chimiques. Ensuite, j’aborderais leurs utilisations comme matériaux sensibles et les modes de transductions. Enfin, j’exposerais les performances métrologiques des capteurs utilisant ces matériaux sensibles vis-à-vis de certains gaz polluants cibles

Improvement in sensitivity and selectivity of InP-based gas sensors : Pseudo-Schottky diodes with palladium metallizations.

The possibility of using single resistive n-type InP semiconductor gas sensors to perform accurate measurements of ozone or nitrogen dioxide concentration in air comes up against their low sensitivity and the inability to discriminate between the influence of each gas on the sensors without any exterior apparatus. To improve these two fundamental aspects of gas sensors, the sensitive n-InP layers have been included in more complex devices, called pseudo-Schottky diodes. Made by successive evaporation of metallic thin layers on p-InP substrates, their Schottky metallization schemes (Pd/Ge/Pd) satisfy a double objective: the creation of the necessary n-InP gas sensitive layer by activation of Ge dopants and the ozone catalytic conversion by palladium layers. Comparisons between the sensing performances of the two gas sensors (resistive and Schottky diode-type ones) show that sensitivity of the laters is largely higher than that of single resistive gas sensors. On the other hand, a good selectivity toward ozone is achieved with Pd/Ge/Pd/p-InP gas sensors, resulting from different reaction kinetics between O3 or NO2 and the sensitive layer. These differences can be attributed to the palladium metallization catalytic activity

A Chemical Microsystem for selective detection of polluting gases in vehicle compartments

International audienceThis paper deals with the design of an original microsystem devoted to the real time monitoring of air polluting gases in vehicle compartments. The selective detection is focused on two species, ozone and nitrogen dioxide, because of their specific toxicity. The gas sensing element is made of thin layers of an organic semiconductor provided with a specific chemical filter. A particular methodology of measurement is implemented, witch allows a selective sensing behaviour. On-board tests are presented

Micro-capteurs haute résolution et sélectifs pour la surveillance des polluants oxydants NO2 et O3 : stratégie, conception et performances

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A Methodology of measurements for phtalocyanine gas sensors dedicated to the detection fo ozone and nitrogen dioxide. Results in urban air pollution context.

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Phthalocyanines based QCM sensors for aromatic hydrocarbons monitoring: Role of metal atoms and substituents on response to toluene

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An original methodology dedicated to real-time detection of oxidizing gases based on pseudo-Schottky diode junction

International audienceThis original methodology has been developed to improve metrological parameters of a pseudo-Schottky diode toward oxidizing species (nitrogen dioxide and ozone). The pseudo-Schottky diode Pd/InP gas sensor ensured selectivity toward oxidizing gases and especially toward O3. This methodology, based on cyclic regenerations of the sensor palladium surface (CO reduction associated with thermal cleaning) and kinetics studies of sensor response, allows us to obtain reproducible measurements of NO2 and O3 concentrations in the range of 20–100 ppb. Our pseudo-Schottky sensor associated to this methodology exhibits low NO2 and O3 threshold values, high resolution, reproducible responses and real-time detection