Synthesis and optical limiting properties of graphene oxide/bimetallic nanoparticles

Bimetallic (Pt and Cu) nanoparticles (NPs) were homogeneously deposited on graphene oxide (GO) sheets, by the hydrothermal reaction of H2PtCl6 and Cu(NO3)2 in the presence of GO. Transmission electron microscopy and X-ray photoelectron and Raman spectroscopies were used to characterize the surface morphology and structure of the GO/bimetallic NPs. Their nonlinear optical (NLO) and optical limiting (OL) properties were characterized by open-aperture Z-scan measurements, using a 532-nm laser with a pulse duration of ∼4 ns. The GO/bimetallic NPs exhibited enhanced NLO and OL properties, compared with GO and GO coated with single-metal NPs. The two-photon absorption of GO sheets, nonlinear scattering of Pt and Cu NPs, inter-band transition of Pt and Cu NPs, and charge transfer between GO and metal NPs all contributed to the enhanced NLO and OL properties of the GO/Pt–Cu NPs. The GO/bimetallic NPs are promising candidates for optical limiters.