Self-Assembly of carbon quantum dots into C8-structured nanosheets

Abstract

Among carbon family, development of carbon nanosheets through a green and simple method is a great challenge, owing to the ineffective synthetic approaches. Furthermore, though various carbon nanosheets are reported as highly efficient energy storage systems, other than graphitic carbon nitride, 2D carbon structures are seldom fluorescent. Here, C8 structured carbon nanosheets were synthesized from self-assembly of biomass derived carbon quantum dots. Their formation and assembly into non-graphitic crystalline 2D structures were investigated in detail with XRD spectra. While addition of PVP incited the formation of crystalline C8 structure, the presence of urea inhibited their growth. Moreover, the PVP could alter the morphology of nanosheets to nanoparticles with same cubic C8 structure. Both nanosheets and nanoparticles exhibited broad blue fluorescence similar to emission spectra exhibited by carbon quantum dots. The fluorescence intensity of C8 nanoparticles were selectively quenched after addition of Cu2+ ions and with a limit of detection of 103 nM. Phytotoxicity and cytotoxicity study of obtained nanosheets confirmed the potential behaviour of nanosheets for biomedical applications.