Structural and optical properties of encapsulated ZnO in porous host matrix

ZnO nanoparticles were encapsulated in the porous activated carbon matrix by incipient-wetness impregnation. The use of the small host matrix allowed the size confinement of ZnO by utilizing the porous nature of the host matrix. Partial fixation of ZnO in the porous matrix determines the size and the dispersion of the particles. Experiments at different calcination temperatures were carried out to investigate structural and optical properties of ZnO nanoparticles in the porous activated carbon matrix using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and photoluminescence. The optimal calcination temperature was found to be ∼450 °C in order to confine ZnO nanoparticles in the porous ACP matrix. Near-band-edge UV emission and green emission were both associated with the deep-level defect state. A decrease in full width at half maximum of E2 mode in Raman spectrum confirmed an increase in crystallite size due to higher calcination temperature, causing an increase in phonon lifetime.