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This article focuses on EPR relaxation measurements in various carbon samples, e.g., natural carbons—anthracite, coal, higher anthraxolites, graphite; synthetically obtained carbons—glassy carbons, fullerenes, graphene, graphene oxide, reduced graphene oxide, graphite monocrystals, HOPG, nanoribbons, diamonds. The short introduction presents the basics of resonant electron spin relaxation techniques, briefly describing the obtained parameters. This review presents gathered results showing the processes leading to electron spin relaxation and typical ranges of electron spin relaxation rates for many different carbon types. [ABSTRACT FROM AUTHOR]

This work presents the preparation and characterization of pristine and transition metal doped partially reduced graphene oxide aerogels. The step-by-step preparation of aerogels from graphene oxide with an assistance of VCl3, CrCl3, FeCl2·4H2O, CoCl2, NiCl2 and CuCl2 chlorides as reducing agents is shown and explained. The influence of reducing agents on the structural and magnetic properties of prepared aerogels is investigated. The use of electron paramagnetic resonance in purification during synthesis of GO and characterization afterwards is shown. It was found that VCl3 was the strongest reducing agent leading to the formation of the most dense reduced graphene oxide aerogel, whereas vanadium is visible in EPR spectrum in form of V4+ complex as a VO2+ groups. [ABSTRACT FROM AUTHOR]

Magnetic properties of zigzag edges of single-layer graphene were investigated by ferromagnetic resonance (FMR)/electron spin resonance (ESR) technique. We observed the FMR lines in single-layer graphene, which provide the most direct experimental proof of the theoretical prediction of ferromagnetic correlations at zigzag edges. To explain the observed temperature dependence of the FMR lines we analyzed the magnetic spin correlation length, which is responsible for magnetic ordering in these quasi-1D ferromagnetic nanodomains formed by zigzag edges. ESR spectra of conduction electrons were also studied. [ABSTRACT FROM AUTHOR]

Abstract: We report pulse ESR studies of the electron spin relaxation processes in graphene. The linear temperature dependences of relaxation rates corresponding to T 1 ≈ T 2 ∼0.1–1μs, similar values of g-factors of possible paramagnetic centres, and the Lorentzian lineshape of the signal indicate the bottleneck effect in spin relaxation of the strongly coupled homogeneous spin system of localized spins and conduction electrons. Interpretation of the data in the frames of the theory of strongly interacting localized and delocalized magnetic moments gives the spin relaxation time of the conduction electrons of an order of 5–30ns, depending on the paramagnetic centres concentration. [Copyright &y& Elsevier]

Graphene and graphene oxide (GO) structures and their reduced forms, e.g., GO paper and partially or fully reduced three-dimensional (3D) aerogels, are at the forefront of materials design for extensive biomedical applications that allow for the proliferation and differentiation/maturation of cells, drug delivery, and anticancer therapies. Various viability tests that have been conducted in vitro on human cells and in vivo on mice reveal very promising results, which make graphene-based materials suitable for real-life applications. In this review, we will give an overview of the latest studies that utilize graphene-based structures and their composites in biological applications and show how the biomimetic behavior of these materials can be a step forward in bridging the gap between nature and synthetically designed graphene-based nanomaterials. [ABSTRACT FROM AUTHOR]