Enhanced photocatalytic activity of BiOI synthesized in presence of EDTA

Bismuth oxyiodide (BiOI) was successfully synthesized by a rapid method using microwave irradiation and by the conventional co-precipitation route. In both cases the synthesis was carried out in aqueous medium using different amounts of EDTA as retarder of the reaction. The physicochemical properties of BiOI such as specific surface area, morphology and photocatalytic activity were directly related with the amount of EDTA added during the formation of the oxyiodide. The photocatalytic activity of BiOI samples was evaluated in the photo-oxidation reaction of nitric oxide in gaseous phase under UV–Vis and visible irradiation. In particular, a strong correlation between the specific surface area of each sample and its photocatalytic activity was observed. For this reason, efforts were focused on finding experimental conditions to obtain BiOI samples with high surface area. The sample with the highest photocatalytic activity (co-precipitation, 40% EDTA) was able to remove 98% of NO from air, showing good stability when was exposed to several cycles of use. Moreover, the selectivity of the photo-oxidation reaction of NO to nitrate ions was of 78%, showing the capacity of the photocatalyst to direct the reaction until the formation of innocuous products.