Ag2O-Ag/CAC/SiO2 composite for visible light photocatalytic degradation of cumene hydroperoxide in water

A visible light-active composite, Ag2O-Ag/CAC/SiO2, was produced by loading an aqueous silver salt solution onto the layer of hydrated calcium aluminate cement coating on porous SiO2 sphere. The mild cement hydration condition induced the formation of in situ Ag2O precipitates on the cement surface which were partially decomposed to metallic Ag after drying and appropriate heat treatment at 200 °C to enhance both decomposition and crystallinity of Ag2O. The coexistence of Ag2O and Ag in the composite was clearly confirmed by XRD and XPS, and the mechanisms for the formation of Ag2O particles on the hydrated cement layer and for the photocatalytic degradation of CHP were also suggested. The photocatalytic activity of Ag2O-Ag/CAC/SiO2 composite (calcined at 200 °C), evaluated under UV and visible lights irradiation through the photodecomposition of CHP in water quantified by HPLC, was two times higher than that of Ag2O-Ag/CAC/SiO2 composite (dried at 45 °C), and able to completely decompose CHP in 5 h. Additionally, the photostability of Ag2O-Ag/CAC/SiO2 photocatalyst remained unchanged for 5 recycling tests.