Improved chemical stability of silver by selective distribution of silver particles on reduced graphene oxide nanosheets

The chemical stability of particles on reduced graphene oxide (RGO) nanosheets is an important issue for the RGO/particles hybrid materials. Here we report that the chemical stability of environmentally sensitive silver can be significantly improved by controlling the distribution of silver particles on RGO nanosheets. By switching the sequence of "deoxygenation" and "deposition", two kinds of RGO/silver hybrids are prepared. The structure and chemical state of silver particles on RGO are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, Raman spectra, transmission electron microscopy and scanning electron microscope. It is found that the graphene/Ag hybrid prepared by "deposition" and then "deoxygenation" can still exhibit obvious surface enhanced Raman scattering (SERS) signals after 10-month storage, compared with the hybrid material fabricated in inverse order. The selective distribution of silver particles and non-uniform dispersion of electrons on RGO nanosheets are responsible for the different performances. This study provides a new insight into preparing chemically stable RGO/particle hybrid materials.