Synthesis of ZnO/Ag hybrid nanostructures using amine functionalized ZnO for study of photocatalytic activity towards organic dyes

In this work, we have functionalized ZnO nanoparticles (NPs) with N-[3-(tri-methoxy-silyl)-propyl]-ethylenediamine to prepare hybrid ZnO/Ag nanostructures. A multi-technique characterization approach has been adopted to unravel structural, morphological and optical properties of the pristine ZnO and hybrid ZnO/Ag nanostructures. The presence of silver nanoparticles on ZnO is supported by XRD, SEM and EDS. SEM results show the presence of silver NPs on the surface of ZnO nanoparticles. Raman analysis reveals a significant broadening and shift of peaks towards lower energy along with reduction in E2 mode intensity for ZnO/Ag hybrid nanostructures, specifying lower crystallinity as compared to ZnO NPs. A higher concentration of defects is supported by Nelson-Riley factor analysis for ZnO/Ag-I hybrid. Photoluminescence quenching shows the high charge-separation efficiency or low electron-hole recombination of hybrid nanostructures. An improvement in the photocatalytic activity of ZnO/Ag-I and ZnO/Ag-II hybrid nanostructures is observed for the degradation of methylene blue, nitrophenol and doxycycline dyes as compared to ZnO. Photocatalytic performance further improved with increase in Ag content due to surface phonon resonance mechanism leading to augmented charge separation.