Abstract
Heteroatom functionalization on a graphene surface can endow the physical and structural properties of graphene. Here, a one-step in situ polymerization method was used for the noncovalent functionalization of a graphene surface with poly-N-vinyl-2-pyrrolidone (PNVP) and the exfoliation of graphite into graphene sheets. The obtained graphene/poly-N-vinyl pyrrolidone (GPNVP) composite was thoroughly characterized. The surface morphology of GPNVP was observed using field emission scanning electron microscopy and high-resolution transmission electron microscopy. Raman spectroscopy and X-ray diffraction studies were carried out to check for the exfoliation of graphite into graphene sheets. Thermogravimetric analysis was performed to calculate the amount of PNVP on the graphene surface in the GPNVP composite. The successful formation of the GPNVP composite and functionalization of the graphene surface was confirmed by various studies. The cyclic voltammetry measurement at different scan rates (5–500 mV/s) and electrochemical impedance spectroscopy study of the GPNVP composite were performed in the typical three-electrode system. The GPNVP composite has excellent rate capability with the capacitive property. This study demonstrates the one-pot preparation of exfoliation and functionalization of a graphene surface with the heterocyclic polymer PNVP; the resulting GPNVP composite will be an ideal candidate for various electrochemical applications.
Highlights
One of the most studied materials is graphene, where carbon atoms are arranged in a honeycomb lattice structure [1,2]
Surface and elemental mapping by Field emission scanning electron microscopy (FESEM) reveals the uniform distribution of PNVP over the graphene surface, and thin layers of graphene sheets were confirmed from FESEM and highresolution transmission electron microscopy (HRTEM) analyses
ATR-FTIR and X-ray photoelectron spectroscopy (XPS) revealed the presence of PNVP on the graphene surface in the graphene/poly-N-vinyl pyrrolidone (GPNVP) composite
Summary
One of the most studied materials is graphene, where carbon atoms are arranged in a honeycomb lattice structure [1,2]. By liquid-phase exfoliation, graphite was exfoliated into graphene using high-boiling solvents such as N-methyl pyrrolidone [23,26]. This leads to the reaggregation of graphene sheets. The prepared polymers were utilized to disperse graphene in different solvents [33,34,35] In these works, we confirmed that the nitrogen in polymers plays a vital role in interactions with graphene surfaces. It was assumed that the oxygen atom might be involved in the interaction with graphene, in addition to the nitrogen atom that might enhance the stability of graphene dispersion This was believed for stable graphene dispersion with poly-N-vinyl-2-pyrrolidone (PNVP). The cyclic voltammetry (CV) measurement of the GPNVP composite was performed at different scan rates (5–500 mV/s) and CV measurements up to 1000 cycles were carried out to reveal the stability of the GPNVP composite
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