Advanced synthesis of nanostructured materials for environmental applications

The present study deals with Aerosol Spray Pyrolysis (ASP) synthesis of two families of nanostructured redox materials targeted to two different environmental applications: transition-metal-doped ferrites and base metal-doped cerium oxide, used for hydrogen production through solar-assisted water splitting and for catalytic soot oxidation, respectively. The synthesized powders were characterized with respect to their phase composition, morphology and particle size distribution by XRD, SEM and TEM analysis, which have shown their nanostructured character. Doped ferrites were evaluated, with respect to their hydrogen production activity from water dissociation, in an in-house built water-splitting testing rig. ASP materials proved to be very active water splitters demonstrating higher water conversion and hydrogen yields than materials of the same composition synthesized through Solid State Synthesis (SSS), with material performance depending on the dopants’ kind and stoichiometry. Base metal-doped cerium oxides were evaluated with respect to their direct soot oxidation activity, via Thermogravimetric Analysis (TGA), as well as on a diesel engine bench under realistic conditions. It was found that doping improves their activity and that they enhance soot oxidation at lower temperatures compared to materials synthesized through Liquid Phase Self-propagating High temperature Synthesis (LPSHS).