A cost-effective and sustainable De-NOx photocatalyst is prepared using zinc acetate and rice husk.ZnO@SiO 2 samples are obtained from the calcination of a homogenised precursor mixture at 600 C.ZnO nanoparticles (70 -180 nm) grow aggregated in spheres and well dispersed (40 -53 m 2 g -1 surface area) covering the silicon skeleton. The corresponding band gap for ZnO@SiO 2 photocatalysts was estimated at 3.1 -3.2 eV. When the samples are irradiated by sunlight in a nitrogen oxide atmosphere the NO HNO 2 NO 2 NO 3 photochemical oxidation takes place. In comparison to unsupportedZnO and TiO 2 -P25, ZnO@SiO 2 samples exhibit high NO X removal values (70 %) and outstanding selectivity (> 90%), the latter related to the sensitivity of zinc oxide towards NO 2 gas. This new photocatalyst is easily recyclable and reusable.
Revised Manuscript (clean for typesetting) Click here to view linked ReferencesIn this study, we report that layered double hydroxides (LDH) exhibited high photocatalytic activities in degrading NOx gases for the first time. ZnAl-CO 3 LDHs with a 1.5 to 3.0 Zn/Al ratio were prepared by a coprecipitation method both with and without hydrothermal treatment. Syntheses were carried out with high and low metal concentrations, the latter being the most favorable in obtaining pure LDHs in the whole Zn/Al ratio range. The samples were characterized by different techniques such as PXRD, FT-IR, ICP mass, TGA, SBET, SEM and Diffuse reflectance (DR). The LDH particles grew as well-defined hexagonal nanolayers, whose size and crystallization depended on the synthetic procedure and the Zn/Al ratio. Those samples with lower crystallinity exhibit the highest specific surface area values (> 50 m 2 •g -1 ). The ZnAl-CO 3 LDHs were UV light responsive with band-gap values close to 3.5 eV. The LDH photocatalysts show a high performance towards the photochemical oxidation process of NO gas, with efficiencies of around 55 %. Remarkably, the ZnAl-CO 3 photocatalysts exhibit an impressive selectivity towards the deNOx process, avoiding the emission of the toxic NO 2 gas into the atmosphere. Interestingly, these promising deNOx results are repeated when working for a long irradiation period or with the highest concentration of NO in polluted atmospheres.
Supported Fe2O3/TiO2 nanocomposites were prepared for the first time by a plasma-assisted route and\ud
successfully tested in photocatalytic NOx abatement driven by solar illumination. In particular,\ud
a sequential low-temperature (<100 °C) plasma enhanced-chemical vapor deposition (PE-CVD)/radio\ud
frequency (RF) sputtering approach was used to fabricate Fe2O3/TiO2 nanocomposites with controlled\ud
composition and morphology. The preparation process was accompanied by a thorough multitechnique\ud
investigation carried out by complementary techniques, including X-ray photoelectron\ud
spectroscopy (XPS), secondary ion mass spectrometry (SIMS), field emission-scanning electron\ud
microscopy (FE-SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The results evidenced\ud
the formation of high purity nanocomposites, in which TiO2 content could be tailored by controlled\ud
variations of the sole sputtering time, and characterized by an intimate Fe2O3/TiO2 contact, of key\ud
importance to exploit the chemical and electronic coupling between the two oxides. The obtained\ud
nanomaterials were tested in NO photo-oxidation activated by sunlight, showing a remarkable activity in\ud
NOx (NO + NO2) removal and a high selectivity (>60%) in their conversion to nitrate species. Overall, the\ud
present performances candidate the present photocatalysts as valuable materials for next-generation\ud
technologies aimed at the abatement of harmful gaseous pollutants
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