Synthesis of graphene–carbon sphere hybrid aerogel with silver nanoparticles and its catalytic and adsorption applications

•We present a facile synthetic method for a graphene-based hybrid aerogel.•The hybrid aerogel exhibits catalytic activity for the reduction of 4-nitrophenol.•The hybrid aerogel effectively adsorbs Cr(VI), U(VI) and methylene blue. In this study, we report the fabrication of a graphene–carbon sphere hybridaerogel decorated with silver nanoparticles (G/AgCS). Graphene oxide (GO) and carbon spheres doped with silver nanoparticles (AgCS) were prepared separately. G/AgCS hydrogel was then synthesized by induced reduction and gelation of a mixture of GO and AgCS in an oil bath. The G/AgCS aerogel was obtained by freeze drying the hydrogel. The synthesized G/AgCS aerogel was characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman and infra-red spectroscopy. The G/AgCS showed promising efficacy for the catalytic reduction of 4-nitrophenol in the presence of NaBH4. The catalytic activity did not significantly decrease during more than 10 cycles of the catalytic reaction. The adsorption capability of chromium(VI), uranium(VI), and methylene blue on the G/AgCS aerogel was also evaluated using a Langmuir isotherm model in comparison to commercial activated carbons.