Self-assembled graphene-based microfibers with eclectic optical properties

Mahdi Ghamsari,Mazaher Ahmadi,Tayyebeh Madrakian,Abbas Afkhami

doi:10.1038/s41598-021-84940-0

Abstract

The construction of graphene-based microfibers with reinforced mechanical and electrical properties has been the subject of numerous researches in recent years. However, the fabrication of graphene-based fibers with remarkable optical features still remains a challenge and has not been addressed so far. This paper aims to report a series of flexible self-assembled fibers, synthesized through a few-minute sonication of thermally oxidized graphene oxide nanosheets, so-called Nanoporous Over-Oxidized Graphene (NOG), in an acidic medium. These free-standing glassy fibers were classified into four distinct morphological structures and displayed a collection of intriguing optical properties comprising high transparency, strong birefringence, fixed body colorations (e.g. colorless, blue, green, and red), tunable interference marginal colorations, UV–visible-near IR fluorescence, and upconversion emissions. Moreover, they exhibited high chemical stability in strongly acidic, basic, and oxidizing media. The foregoing notable attributes introduce the NOG fiber as a promising candidate both for the construction of graphene-based photoluminescent textiles and the development of a wide variety of optical applications.

Highlights

The construction of graphene-based microfibers with reinforced mechanical and electrical properties has been the subject of numerous researches in recent years
A new type of nanoporous graphene which was synthesized through thermal oxidation of orderly graphene oxide sediments (OGOS) up to 800 °C showed a great promise in this regard
At first, in an effort to shed a light upon the role of thermal oxidation in the synthesis of Nanoporous Over-Oxidized Graphene (NOG) nanosheets, the changes of OGOS during this process were inspected by means of TGA, Transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), and UV/visible absorption analyses

Summary

Introduction

The construction of graphene-based microfibers with reinforced mechanical and electrical properties has been the subject of numerous researches in recent years. This paper aims to report a series of flexible self-assembled fibers, synthesized through a few-minute sonication of thermally oxidized graphene oxide nanosheets, so-called Nanoporous Over-Oxidized Graphene (NOG), in an acidic medium These free-standing glassy fibers were classified into four distinct morphological structures and displayed a collection of intriguing optical properties comprising high transparency, strong birefringence, fixed body colorations (e.g. colorless, blue, green, and red), tunable interference marginal colorations, UV–visible-near IR fluorescence, and upconversion emissions. A new type of nanoporous graphene which was synthesized through thermal oxidation of orderly graphene oxide sediments (OGOS) up to 800 °C showed a great promise in this regard This unique material, so-called nanoporous over-oxidized graphene (NOG), showed remarkable optical properties including high transparency, UV–visible-near IR fluorescence, as well as upconversion luminescence (UL). The transformation mechanism of NOG nanosheets into the selfassembled microfibers together with the characterization of the resulting fibers were discussed on the basis of optical microscopy, polarized-optical microscopy, epifluorescence microscopy, confocal laser scanning microscopy, FE-SEM, TEM, and DLS spectrophotometry findings

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