Encapsulation of Ag nanoparticle-carbon composite and enhancement of visible light ZnO nanorods photodiode

Surface modification on zinc oxide nanorods (ZnO NRs) by encapsulating with silver nanoparticles-carbon (Ag NPs-C) composite was done and its characterisation was undertaken. Field emission scanning electron microscopy (FESEM) shows a thin film of Ag NPs-C encapsulating the ZnO NRs. Diffuse reflectance spectroscopy (DRS) shows Ag NPs-C has higher reflectance in the 320-380 nm range, with a small absorption peak at 320 nm due to Ag NPs plasmonic effect. ZnO NRs encapsulated with the composite records a broader peak and slight red shift in the photoluminescence (PL) spectra. The composite encapsulating the ZnO NRs introduces new energy states in the ZnO lattice structure, resulting in the encapsulated ZnO NRs more photosensitive to longer wavelength (460 nm) compared to unencapsulated ZnO NRs which is more photosensitive to ultraviolet wavelength (395 nm).