Lack of enhanced photocatalytic formation of iodine on particulate semiconductor mixtures

Under UV-A light illumination, formation of iodine from iodide ion on the surfaces of anatase TiO2, ZnO, Fe2O3, CeO2, MoO3, Bi2O3, and Nb2O5 increases with the concentration of iodide ion, airflow rate and light intensity and conform to the Langmuir-Hinshelwood kinetic model. Measurement of the particle size of the semiconductor oxides by light scattering method and deduction of the same from the determined specific surface area show that the oxide particles agglomerate in suspension. However, mixtures of any two listed particulate semiconductors do not show enhanced photocatalytic formation of iodine indicating absence of interparticle charge transfer. The results are rationalized.

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► Iodine photoformation on oxide surface follows Langmuir-Hinshelwood kinetics.
► Semiconductor particles under suspension agglomerate.
► Photocatalyzed iodine formation is not enhanced by particulate semiconductor mixtures.