Regulation and enhancement of the optical performance of graphene oxide through Ni/Fe/Ag nanoparticles doping

Graphene oxide (GO) is a two-dimensional carbon material with a graphene-like structure and many oxygen-containing functional groups, and in recent years from research into the unique optical properties of GO, GO-based composite materials formed by combining with other materials have shown improved overall performance. Reported here is an investigation of how doping with Ni, Fe, and Ag nanoparticles affects the linear and nonlinear optical properties of GO films. The morphology and structure of films of GO, GO with Ni nanoparticles, GO with Fe nanoparticles, and GO with Ag nanoparticles were studied by laser scanning confocal microscopy, SEM, energy dispersive spectroscopy, XRD, and Raman spectroscopy. UV–visible absorption spectra were used to study the optical absorption properties, and the optical band gaps of GO and the composites were calculated from those spectra via Tauc plots. The results show that the band gaps of GO films can be effectively regulated by metal nanoparticles, and so the properties of GO composites can be manipulated. The nonlinear optical properties of GO and GO–metal-nanoparticle composite films were studied by femtosecond laser Z-scanning. The results show that the femtosecond laser power can be tuned to the optical limiting behavior of GO. The strong synergistic coupling effect between metal nanoparticles and GO enhances the nonlinear absorption and nonlinear refraction of composite thin films. The nonlinear absorption coefficient of the composite thin films is improved significantly, and the optical limiting properties are excellent. GO–metal-nanoparticle composite materials have potential applications and advantages in improving optical absorption, band-gap control, and optical limiting. They can promote the expansion of GO composite materials in various practical applications and are candidates for good optical materials, opening the way to GO photonics.