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The detection of organophosphorous compounds remains one of the major issues to be addressed in order to prevent chemical threats. For that purpose, the need of sensitive and selective sensor is of great importance. In this study, we decided to use microcantilevers whose principle is based on the modification of their resonance frequency due to molecule adsorption onto their surface. The idea of this project is to combine the nanostructuration and functionalization to improve cantilevers performances. Thus, the microcantilevers surface was nanostructured using solvothermal method with TiO2 nanorods to increase their adsorption capacity and then, cantilevers sensibility. Those nanostructured cantilevers was then functionalized by molecules able to specifically bind OPs molecules to improve sensors selectivity. The nanostructuration and functionalization were first optimized on silicon substrates before being transferred onto cantilevers. A parametric study was performed to evaluate the impact of synthesis conditions on the nanostructures morphology. The molecules loading on TiO2 nanorods was evaluated and the best nanostructure was reproduced on cantilevers to carry out detection tests of an OPs simulant. Specific investigation was also performed to understand the interaction mechanism between OPs and TiO2.; La détection d’agents organophosphorés (OPs) demeure l’un des problèmes majeurs à résoudre pour prévenir la menace chimique. A cet effet, la recherche de capteurs sensibles, sélectifs, portables reste d’un grand intérêt. Dans ce projet, notre intérêt s’est porté vers des microleviers dont le principe repose sur la modification de leur fréquence de résonance due à une adsorption de molécules à leur surface. Un concept associant la nanostructuration et la fonctionnalisation a été étudié pour améliorer les performances des leviers. Ainsi, la surface des microleviers a été nanostructurée par voie solvothermale avec des nanobâtonnets de TiO2 pour accroitre leur capacité d’adsorption et leur sensibilité. Ces leviers nanostructurés ont ensuite été fonctionnalisés par des molécules (alcool, oxime) susceptibles de se lier spécifiquement aux OPs pour améliorer leur sélectivité. La nanostructuration et la fonctionnalisation ont été préalablement optimisées sur des surfaces modèles avant d’être transférées sur des leviers. Une étude paramétrique a été menée pour évaluer l’impact des conditions de synthèse sur la morphologie des structures. La capacité de greffage des nanostructures a été évaluée et les meilleures structures ont été reproduites sur les leviers pour les tests de détection d’un simulant d’OPs. Des études plus spécifiques ont également été menées pour comprendre les mécanismes d’interactions entre les OPs et le TiO2.

The detection of organophosphorous compounds remains one of the major issues to be addressed in order to prevent chemical threats. For that purpose, the need of sensitive and selective sensor is of great importance. In this study, we decided to use microcantilevers whose principle is based on the modification of their resonance frequency due to molecule adsorption onto their surface. The idea of this project is to combine the nanostructuration and functionalization to improve cantilevers performances. Thus, the microcantilevers surface was nanostructured using solvothermal method with TiO2 nanorods to increase their adsorption capacity and then, cantilevers sensibility. Those nanostructured cantilevers was then functionalized by molecules able to specifically bind OPs molecules to improve sensors selectivity. The nanostructuration and functionalization were first optimized on silicon substrates before being transferred onto cantilevers. A parametric study was performed to evaluate the impact of synthesis conditions on the nanostructures morphology. The molecules loading on TiO2 nanorods was evaluated and the best nanostructure was reproduced on cantilevers to carry out detection tests of an OPs simulant. Specific investigation was also performed to understand the interaction mechanism between OPs and TiO2., La détection d’agents organophosphorés (OPs) demeure l’un des problèmes majeurs à résoudre pour prévenir la menace chimique. A cet effet, la recherche de capteurs sensibles, sélectifs, portables reste d’un grand intérêt. Dans ce projet, notre intérêt s’est porté vers des microleviers dont le principe repose sur la modification de leur fréquence de résonance due à une adsorption de molécules à leur surface. Un concept associant la nanostructuration et la fonctionnalisation a été étudié pour améliorer les performances des leviers. Ainsi, la surface des microleviers a été nanostructurée par voie solvothermale avec des nanobâtonnets de TiO2 pour accroitre leur capacité d’adsorption et leur sensibilité. Ces leviers nanostructurés ont ensuite été fonctionnalisés par des molécules (alcool, oxime) susceptibles de se lier spécifiquement aux OPs pour améliorer leur sélectivité. La nanostructuration et la fonctionnalisation ont été préalablement optimisées sur des surfaces modèles avant d’être transférées sur des leviers. Une étude paramétrique a été menée pour évaluer l’impact des conditions de synthèse sur la morphologie des structures. La capacité de greffage des nanostructures a été évaluée et les meilleures structures ont été reproduites sur les leviers pour les tests de détection d’un simulant d’OPs. Des études plus spécifiques ont également été menées pour comprendre les mécanismes d’interactions entre les OPs et le TiO2.

International audience; Vertically aligned TiO2 nanorods have been successfully synthesized on the micrometric surface of a cantilever by a two-step procedure involving solvothermal method. Adjusting TiO2 synthesis conditions, first optimized on centimetric silicon substrate, allowed to well-control the morphology of the nanorods, aimed to increase the collection surface of this micromechanical sensor. By using the nanostructured microcantilever for the detection of organophosphorous agent (OPs), a frequency shift of 833 Hz corresponding to a remarkable enhancement of the sensor sensitivity by a factor of 75 compared to a pristine cantilever is achieved. Moreover, functionalization of this nanostructured cantilever with a tailored functional oxime molecule having strong affinity with OPs compounds significantly improved the performance of the sensor in vapor phase. A frequency shift of 1319 Hz is obtained at 500 ppm of DMMP with the functionalized sensor.

The presence of AMPA in environment becomes today a real problem due to its persistence, its toxicity, and its multiple origins (main metabolite of glyphosate, the pesticide the most used in the world; degradation product of personal care and industrial products). This paper reports the development of a simple, effective, cheap and easy electrochemical treatment, for mineralising AMPA under very soft conditions: at room temperature, at free pH, and in a classical open electrochemical cell. The electrode material used is an electrodeposited thin film of birnessite, a non-toxic material, synthesised in very soft conditions. The original idea is to couple the spontaneous oxidative properties of birnessite to an electrochemical oxidation treatment in the aim to increase its reactivity towards this pollutant. Very good mineralisation rates and capacity (≈0.115 g AMPA mineralized by gramme of birnessite) were obtained with very low energy supplies (Q ≈ 3 C). Some tests performed with concentrated glyphosate solutions, one of its main parents, give also good results allowing us to envisage the development of an easy method of wastewater treatments at very low costs in complement of classical methods and/or directly at the source of pollution. Keywords: Layered manganese oxides, Phyllomanganate, Organophosphorous compounds, Phosphonates, Glyphosate

International audience; Organophosphorous compounds are involved in many toxic compounds such as fungicides, pesticides, or chemical warfare nerve agents. The understanding of the decomposition chemistry of these compounds in the environment is largely limited by the scarcity of thermochemical data. Because of the high toxicity of many of these molecules, experimental determination of their thermochemical properties is very difficult. In this work, standard gas-phase thermodynamic data, i.e. enthalpies of formation (Hf°298), standard entropies (S°298) and heat capacities (Cp°(T)) were determined using quantum chemical calculations and more specifically the CBS-QB3 composite method which was found the best compromise between precision and calculation time among high accuracy composite methods. A large number of molecules was theoretically investigated, involving trivalent and pentavalent phosphorus atoms, and C, H, O, N, S and F atoms. These data were used to propose 83 original groups, used in the semi-empirical group contribution method proposed by Benson. Thanks to these latter group values, thermochemical properties of several nerve agents, common pesticides and herbicides have been evaluated. Bond dissociations energies (BDE), useful for the analysis the thermal stability of the compounds, were also determined in several molecules of interest.