Facile assembly of BiOI/GO composites with enhanced photocatalytic activity for NO photooxidation under visible light irradiation

Abstract

The most effective approach to develop new photocatalysts involves solar activation and prevention of the recombination of photogenerated hole–electron pairs. To achieve these goals, in this work, a series of bismuth oxyiodide and graphene oxide (BiOI/GO) composites were synthesized by a simple ex situ method. The structural, morphological, optical, and electrical properties of the synthesized compounds were thoroughly investigated. The photooxidation reaction of NO in the gas phase under visible light irradiation was used to assess the photocatalytic activity of BiOI/GO composites. The results showed that a small amount of GO significantly improved the photocatalytic activity. The BiOI/GO-0.5% sample prepared with 0.5 wt% GO showed the highest NO conversion (∼100%), indicating excellent photocatalytic stability after four continuous irradiation cycles and a high selectivity of 97% for nitrate ion formation. The increase in photocatalytic activity was mainly related to increased light absorption, high specific surface area, and better separation of light-generated charges. The use of chemical scavengers contributed to clarifying certain aspects of the possible photooxidation process of NO, which demonstrated that superoxide radicals (˙O₂⁻) could be the main factor responsible for the photodegradation of NO by BiOI/GO-0.5%.