Abstract
The transfer-free fabrication of the high quality graphene on the metallic nanostructures, which is highly desirable for device applications, remains a challenge. Here, we develop the transfer-free method by direct chemical vapor deposition of the graphene layers on copper (Cu) nanoparticles (NPs) to realize the hybrid nanostructures. The graphene as-grown on the Cu NPs permits full electric contact and strong interactions, which results in a strong localization of the field at the graphene/copper interface. An enhanced intensity of the localized surface plasmon resonances (LSPRs) supported by the hybrid nanostructures can be obtained, which induces a much enhanced fluorescent intensity from the dye coated hybrid nanostructures. Moreover, the graphene sheets covering completely and uniformly on the Cu NPs act as a passivation layer to protect the underlying metal surface from air oxidation. As a result, the stability of the LSPRs for the hybrid nanostructures is much enhanced compared to that of the bare Cu NPs. The transfer-free hybrid nanostructures with enhanced intensity and stability of the LSPRs will enable their much broader applications in photonics and optoelectronics.
Highlights
Graphene as two-dimensional one-atom-thick sheet of carbon has shown its potential for a wide variety of applications[1,2,3]
The as-grown graphene on the Cu NPs is beneficial to their full electric contact and strong interactions on account of the larger adhesion energy. 10-fold enhancement of fluorescence from the dye coated hybrid nanostructures has been obtained due to graphene-induced enhanced localized surface plasmon resonances (LSPRs), which has been supported by finite-difference time domain (FDTD) calculation
The surface morphologies of the copper nanoparticles coated with and without the as-grown graphene layers are investigated by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) and shown in Fig. 2a,b, respectively
Summary
Graphene as two-dimensional one-atom-thick sheet of carbon has shown its potential for a wide variety of applications[1,2,3]. An enhanced intensity of the LSPRs induced by the enhanced light–matter interactions is expectable for the hybrid nanostructures of graphene/metal NPs. Copper (Cu) has competitive advantages over the noble metals in low cost, compatibility of integrated circuit, high thermal and electrical conductivities and low electro-migration resistance[20,21,22,23]. The as-grown graphene/Cu NPs hybrid nanostructures exhibit enhancements in both intensity and stability of the LSPRs due to the graphene-induced enhancement in the light–matter interactions and the surface passivation. The stability of the LSPRs for the hybrid nanostructures is much enhanced compared to that of the bare Cu NPs due to the surface passivation of the graphene sheets covering completely and uniformly on the Cu NPs. Our findings might open up a new avenue to realize high quality graphene/Cu NPs hybrid nanostructures and fulfil their practical applications in photonics and optoelectronics
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