Regeneration of oxygenated functional groups on thermally reduced graphene oxide nanosheets via diluted oxygen DBD cold plasma

Abstract

Although stacked graphene oxide (GO) possesses abundant oxygenated functional groups, it suffers from limited specific surface area. This study aims to enhance the specific surface area of graphene oxide via thermal expansion and subsequently oxygenated functional groups using a dielectric barrier discharge (DBD) cold plasma. GO was synthesized via improved Hummer's method, followed by rGO reduction at 520 ℃. The rGO was treated by DBD cold plasma with N2 and O2 gases at various powers and exposure times. The resulting samples were characterized using several techniques, including TPD, FTIR, Boehm titration, BET, Raman spectroscopy, FESEM and EDS. The results showed that increasing O2 in the feed gas up to 47 % and plasma power enhanced oxygenated functional groups on plasma-functionalized rGO (PF-rGO). The exposure time significantly influenced the oxygen content of the functional groups; PF-rGO samples with 5 min exposure time exhibited superior specific surface area, water stability, and Cd2+ adsorption capacity compared to samples treated for 15 min. As plasma exposure time increased, layer stacking and oxygenated group density increased. Raman spectroscopy confirmed the enhancement of oxygen groups on the rGO surface treated with O2-N2 plasma. These findings provide valuable insights for designing and developing of graphene-based materials with tailored properties and enhanced performance for energy-related applications.