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

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.