Mesoporous carbon with extremely low micropore content synthesized from graphene oxide modified with alkali metal nitrates

High-temperature thermal exfoliation is a simple, rapid, and cost-efficient method for transforming graphene oxide (GO) materials into reduced graphene oxide (rGO) materials. In this study, GO materials were dispersed with alkali metal nitrates (MNO3), leading to the preparation of porous rGO materials characterized by high specific surface area (SSA) and pore volume via high-temperature thermal exfoliation. Experimental data indicate that the metal cations of MNO3 tend to react directly with the oxygen functional groups (OFG) of GO, modulating the OFG content. Simultaneously, nitrate anions have preferential interaction with alkali metal ions and adhere to the surface of the GO. The presence of MNO3 on the surface of GO facilitates the thermal exfoliation process and leads to the formation of structures with an extremely high proportion of mesoporous content. The isothermal gas adsorption results show that the exfoliation efficiency of the samples activated with different nitrate salts decreases in the order rGO-KNO3 > rGO-NaNO3 > rGO-LiNO3. Among these samples, rGO modified with KNO3 exhibited the greatest exfoliation efficiency, with a mesopore-to-micropore volume ratio of 22.4, more than 1.7 times that of rGO. Its SSA and pore volume were 359 m2 g−1 and 1.26 cm3 g−1, respectively. These values significantly surpass those of rGO. Our research findings demonstrate that activation with MNO3 significantly increases the SSA and pore volume of the GO material after high-temperature annealing.

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