Modulation of the functional properties by composition tailoring in Bi12O17Cl2/(BiO)2CO3 nanocomposite materials

In the field of environmental remediation strategies, multifunctional materials able to act both for fast pollutants adsorption and degradation under visible light are highly desirable. In this framework, bismuth oxyhalogenides (BimOnXo, X= Cl, Br, I), and (BiO)2CO3 nanostructures represent an interesting solution owing to their peculiar physico-chemical properties, layered structures, morphologies and low toxicity. Besides single phase materials, composite systems that display heterojunction structures, e.g. BiOCl/Bi2O3, BiOCl/BiOI, BiOI/Bi12O17Cl2, can operate far better thanks to the presence of synergic effects at the interface between the two components. The present study explores the modulation of chemico-physical properties, adsorption capacity and photodegradation activity towards model pollutants, i.e. Rhodamine B (RhB) and Methyl Orange (MO), of Bi12O17Cl2/(BiO)2CO3 nanocomposite materials, by tailoring the relative amount of the two components through different post-synthe sis treatments with UV-light or thermal annealing. In this regard, Bi12O17Cl2 is used as sensitizer to harvest the visible light being coupled to (BiO)2CO3 which has almost no visible absorption. The obtained results evidenced the ability of the employed strategy to modulate morphology, surface areas, ?-potential, optical absorption in the visible range and dye adsorption/degradation properties. The best performance was achieved by (BiO)2CO3-rich samples which adsorbed 80% of MO within 10 minutes contact time and decomposed the remaining 20% by visible light photocatalysis. Bi12O17Cl2-rich composite materials displayed a lower adsorption ability, but thanks to the stronger absorption in the visible they behaved as more effective photocatalysts.