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The project is structured into 5 work packages which will involve the 2 units and the subunit, i.e. U1 (University of Ferrara), U2 (POLIMI), SU (Bruno Kessler Foundation). The temporal program is summarized in the following Gantt diagram, in which the deliverables are also reported.
WP1 - Materials production and characterization (M 1-6)
Task 1.1 - Synthesis of nanocrystalline ZnSe and ZnTe
Task 1.2 - Nanopowders characterization
WP2 - Optical properties (M 3-10)
Task 2.1 - Optical characterization
Task 2.2 - Photoconductive characterization
Task 2.3 - Transient absorption spectroscopy
WP3 - Fabrication, characterization of sensors (M 4-12)
Task 3.1 - Production of devices
Task 3.2 - Photoconductive measurements under controlled atmosphere
WP4 - Operando investigation on solid-gas phase under visible light activation (M 11-24)
Task 4.1 - Operando DRIFT measurements on photo-activated gas sensors
Task 4.2 - Operando Confocal micro-Raman measurements on photo-activated gas sensors
Task 4.3 - Gas sensing mechanism interpretation
Task 4.4 - ELETTRA: Operando DRIFT measurements on synchrotron light activated gas sensors
WP5 - Dissemination and public engagement (M 9-24)
Expected results and advancement of knowledge
The investigation on the light activation of semiconductor gas sensors proposed by the LEVANTO project plays an important role in modern materials science due to its interdisciplinary nature and the perspectives for practical application of the results. The deliverables (D) of the LEVANTO project lie in the definition of a well established procedure to investigate the sensing mechanism of semiconductors (SC) photoactivated by visible light, paving the way for the exploitation of the potentialities of such an activation method.
D1. High quality nanocrystalline semiconductor materials for visible light activation. We firstly expect to merge the well-established electrically conductive properties of ZnSe and ZnTe with their optical properties, which are inherently present in them but not still explored, in the case of ZnTe, or completely explored, in the case of ZnSe, for photoactivated gas sensing. The modulation of conducting properties by optical stimulation would primarily enhance the exploitation of potential properties of SCs under test and then would further strengthen their capabilities for gas sensing.
D2. Effective SC optical properties and radiation parameters for photoactivation in the visible light range. The extensive optical characterization of both powders and films will guide the production of highly functional SC and then to effective photoactivated gas sensing devices. Moreover, these characterizations will support the identification of an established correlation between optical properties of SC and experimental irradiation parameters for their visible light activated gas sensitivity.
D3. Validation of operando spectroscopic techniques for gas sensitivity photoactivation. The LEVANTO project will actively contribute to the development and validation of innovative methods for the study of sensing mechanisms under visible light activation. In general, DRIFT spectroscopy is still limited in its use in research on SC gas sensitivity, also in thermal activation mode. So far, to the best of our knowledge, the setup proposed in this project is the first that allows the experimentation of DRIFT spectroscopy for photoactivated gas sensing SC devices. At the same time, the implementation of the operando approach for both DRIFT and micro-Raman spectroscopy is completely new and makes these analysis methods significantly progressive.
D4. Photoactivation addressed to reducing gases. It is well-known that most photoactivated sensors are more sensitive to oxidizing molecules, such as NO and O, and only few works reported photo-enhanced sensitivity to H. Starting from the preliminary works on ZnSe and ZnTe gas sensors developed in the last years, which demonstrated a sensitivity of these functional SC towards such interesting gases, i.e. SO and CO, an additional deliverable that the LEVANTO project would achieve is concrete effort to develop high performance detection also of reducing gases, such as organic compounds.
Visible light activated gas sensors based on semiconductors: an operando investigation by DRIFT and confocal micro-Raman spectroscopy
LEVANTO
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