Synthesis, characterization and application of graphene-based silver orthophosphate nanocomposite in organic dye degradation

The visible light driven semiconductor photocatalyst is a promising material in environmental pollution mediation. Silver orthophosphate has attracted considerable attention for its applications in this field. But the photocatalytic activity and stability is limited due to its photocorrosion during photocatalysis. In this work, a modified reduced graphene oxide (RGO) based silver orthophosphate heterostructure nanocomposite was synthesized by sol-gel and hydrothermal method. The nanocomposite was characterized by XRD, SEM, Raman, FTIR, diffuse reflectance spectra (DRS) and photoluminescence (PL) spectroscopy. The XRD and SEM indicated the formation of cubic silver orthophosphate nanoparticles deposited on RGO sheets. The FTIR and Raman spectra showed the interaction of silver orthophosphate nanoparticles with RGO. The DRS showed higher absorption of visible radiation and PL implied that these nanocomposites could effectively separate the photogenerated electron-hole pairs. The photocatalytic activity was tested in decolourization of Acid Blue 25, a toxic anthraquinonic dye in aqueous medium under visible light illumination. The kinetics of the degradation was studied by modified Langmuir-Hinshelwood mechanism. The result of this work revealed that heterostructure nanocomposite of silver orthophosphate grafted on reduced graphene oxide sheets could be easily synthesized by simple sol-gel and hydrothermal method and the photocatalytic activity of silver orthophosphate was greatly enhanced when integrated with RGO.