Nanostructured vanadium pentoxide gas sensors for SCR process control

Abstract

Different types of vanadium pentoxide nanostructures were fabricated by pulsed laser deposition and were studied as gas sensing materials to control selective catalytic reduction process. X-ray diffraction and Raman spectroscopy studies confirmed that the fabricated layers consisted solely of pure V2O5 phase. The film surface morphologies were examined by atomic force microscopy. The results showed that microstructures of the films were strongly dependent on the deposition parameters used in the pulsed laser deposition process. The morphologies of the film surfaces varied also between denser films and highly porous layers formed of agglomerated nanoparticles. The electrical conductivity-based gas sensing measurements showed strong selectivity to ammonia in comparison to NO and CO gases in the cross-sensitivity tests. The films were capable of detecting 20 ppm of NH3 even in the presence of the interfering gases of NO and CO, and also in varying O2 background concentrations. Furthermore, the films were found to show very stable gas response over the time period longer than 450 h. These are very promising results when considering possible sensing applications, e.g., control of selective catalytic reduction process in diesel engine exhausts with very strict and challenging specifications set by car industry.