The effect of the degree of oxidation on broadband nonlinear absorption and ferromagnetic ordering in graphene oxide

Abstract

We report on the effect of the degree of oxidation on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. As more sp(3) states evolved with the rise in oxidation degree, it turned out that the sp(2)/sp(3) fraction and sp(2) clustering are crucial parameters for tuning the broadband non-linear optical absorption over a wide range from ps to ns laser pulses for both visible and infrared laser irradiation. This was clearly confirmed by two different approaches, namely by a synthetic route through the gradual oxidation of graphene oxide from 1 to 3 oxidizing cycles, and reversely by in situ reduction of graphene oxide by UV laser irradiation. Furthermore, as the sp(3) states carry localized magnetic moments, ferromagnetic ordering is observed at low temperatures. The magnetization and temperature at which ferromagnetic ordering evolves are found to increase on increasing the oxidation degree. The tuning of non-linear optical and magnetic properties of graphene oxide by oxidation/reduction thus provides an easy way to endow graphene oxide with tunable physical features highly required in both optoelectronics and spintronics applications.

Nonlinear optical response of some Graphene oxide and Graphene fluoride derivatives

“…Tak-ing into account that the studied samples were prepared having similar degree of transformation of their sp 2 bonds to sp 3 ones, this reveals convincingly that the ratio sp 2 /sp 3 can be an effective and reliable parameter in order to control the NLO response of these graphene derivatives, confirming results from previous studies [24,29]. Another interesting issue arising from the present results is the effect of the pulse length of the laser excitation on the NLO response.…”

“…the sp 2 /sp 3 ratio. The ability to tune this ratio allows the continuous tuning of GO's band gap, suggesting an efficient way for the tailoring of GO's NLO response [24,29]. However, this dependence is neither simple nor straightforward because of the non-stoichiometric nature of GO samples.…”

“…In particular, concerning the range of the optical frequencies, inter-band optical transitions can occur at all photon energies. Beyond the typical SA response of pristine graphene and the optical limiting effect due to nonlinear scattering (NLS) [20], its derivatives have been shown to exhibit several other important NLO effects, such as two-photon and multiphoton absorption (TPA) [21,22], reverse saturable absorption (RSA) [22][23][24], and optical limiting [25][26][27]. Therefore, graphene exhibits excellent photophysical properties and large optical nonlinearities over a wide range of laser pulse lengths, which makes it a highly promising candidate for several potential applications including fast optical communications, all-optical switching, optical limiting, etc.…”

Impact of various oxidation degrees of graphene oxide on the performance of styrene–butadiene rubber nanocomposites

“…It suggests that the oxygen‐containing groups such as hydroxyl and epoxy groups were introduced onto the surface of GO. Compared with GO3, with increasing oxidation degree, two more peaks at 287.3 eV and 288.8 eV appear in GO9, GO15, and GO21, which are attributed to CO and OCO bond, respectively . It indicates that further increases in oxidation degree result in the formation of carbonyl groups along with the carboxyl groups.…”

“…In the C1s spectrum of GO3 (Fig. d), three main peaks appear at 284.6 eV, 285.8 eV, and 286.7 eV, corresponding to the bonds of CC, COH, and COC, respectively . It suggests that the oxygen‐containing groups such as hydroxyl and epoxy groups were introduced onto the surface of GO.…”