Create chemically hazardous gas detectors organophosphorus and nitrogen-containing substances on the basis of selective nanocrystalline semiconductors and molecular sieve

       The project aims to design and develop a prototype analyzer for automatic detection of toxic products in the air, including toxic organophosphorus compounds and nitrogen-containing toxic rocket fuel component. We plan to create a multi-channel analyzer through a detector which comprises a semiconductor in addition to the selective line of resistive type sensors , the sampling system also allowing to carry out a catalytic conversion and concentration of target gases. Joint analysis of sensor signals based on the software developed allows to detect the presence of toxic and explosive substances and determine simultaneously to 5 industrial air pollutants at 0.5 - 10 MPC working area.
    The methods of physical and chemical modifiers application clusters of different size and chemical nature. The high stability of nanocomposites in time in the temperature range 100 - 500^oC . Developed methods for determining the nature and concentration of active sites on the surface. The technique of applying the sensitive material on a microelectronic chip. Created a fully automated apparatus for measuring the sensor signal with a system of electronic flow meters for dilution calibration gas mixtures to the MCL . Created a database of the most promising nanocomposites for the detection of various groups of the main pollutants and toxic and explosive molecules in the air .
    The technical principles of the system pre-concentration of the molecules H₂S, NO_x, NH₃ and their retention . The authors of the project developed synthetic approaches to control the pore geometry in these systems, and therefore carry a targeted synthesis of materials with desired porous characteristics required for the selective separation and concentration of gas mixtures of given composition. Along with the molecular sieve properties of these materials exhibit ion exchange , acid / basic , oxidation / reduction and catalytic properties . New materials with combined micro-mesoporous system combines the advantages of zeolites and mesoporous molecular sieves: high thermal stability, acid, molecular sieve properties, large adsorption capacity and the absence of diffusion limitations for the transport of adsorbate molecules .

    During the reporting period for the effective detection of low concentrations of phosphorus compounds in the air has been proposed system consisting of adsorption hubs and semiconductor gas sensors. As sorbents preferably concentrating the use of silicates with a low density of surface hydroxyl groups which provides for a high degree of thermal desorption of recovering the target compound without decomposition. As sensor materials tested nanocomposites based on tin dioxide and modifier - PdOh clusters , PtOh , RuOh and d-oxides of the elements CuO, Fe₂O₃, MoO₃, V₂O₅. The most sensitive material is SnO₂, RuO₂ modified Using a combination of " hub-sensor " possible to detect DMMP at concentrations below 0.1 mg/m³, shows stable and reproducible operation of the system upon detecting DMMP to more than 500 cycles of adsorption - thermal desorption .
KEYWORDS

Metal oxides , nanocrystalline semiconductors, sensitizers , quantum dots CdSe, light, solid - gas reactions , electrical , sensors, catalysts