Halloysite–CeO2–AgBr nanocomposite for solar light photodegradation of methyl orange

Halloysite nanotube supported hybrid CeO2–AgBr nanocomposite was synthesized by a facile microwave mediated method. The molar ratio of CeO2 and AgBr in the halloysite–CeO2–AgBr nanocomposite was adjusted so that r = nAg/(nAg + nCe) was selected as 0.0, 0.25, 0.33, 0.40, 0.45, and 0.50 respectively. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible diffused reflectance spectroscopy (UV–Vis) were employed to investigate the structure and optical properties of the nanocomposites. Results indicate that among the pure halloysite and CeO2–AgBr loaded halloysite nanocomposites, the molar fraction r has a critical effect on the photocatalytic activity, which increases as the AgBr content increases to r ≤ 0.4 and decreases when r > 0.4. The highest conversion of methyl orange reached 99% within 80 min by using halloysite–CeO2–AgBr at r = 0.4, which was much higher than pure halloysite and CeO2–AgBr. As an exploratory study, the introduction of AgBr species was found to extend the spectral response from UV to visible region and improve the separation of electron–hole pairs. The repeatable use of the nanocomposite photocatalyst with little depreciation was also confirmed.