Robust magnetic moments on the basal plane of the graphene sheet effectively induced by OH groups

Abstract

Inducing robust magnetic moments on the basal plane of the graphene sheet is very difficult, and is one of the greatest challenges in the study of physical chemistry of graphene materials. Theoretical studies predicted that introduction of a kind of sp3-type defects formed by OH groups is an effective pathway to achieve this goal [Boukhvalov, D. W. & Katsnelson, M. I. ACS Nano 5, 2440–2446 (2011)]. Here we demonstrate that OH groups can efficiently induce robust magnetic moments on the basal plane of the graphene sheet. We show that the inducing efficiency can reach as high as 217 μB per 1000 OH groups. More interestingly, the magnetic moments are robust and can survive even at 900°C. Our findings highlight the importance of OH group as an effective sp3-type candidate for inducing robust magnetic moments on the basal plane of the graphene sheet.

Magnetism of graphene quantum dots

“…As reported, the magnetic moments of GO come from two categories: oxygen groups and vacancies on the basal plane, and spin polarized states at zigzag edges. 36 As mentioned above, the XPS and Raman characterizations indicate that oxygen groups and vacancies on the basal plane have been removed by annealing at the high temperature of 1010°C. The basal plane of GQDs is nearly perfect, which would not contribute to the magnetism.…”

“…In addition, the basal-plane defects such as point vacancies or chemisorbed OH groups on the basal plane of graphene sheet would induce magnetic moments. 36,49 Despite that our GQDs have nearly perfect basal planes, one can't exclude the possibility that there may still be some residual defects on the basal plane of GQDs sheet. Namely, defects on the basal plane may more or less contribute to the magnetism of our GQDs.…”

“…27,29 Notably, the hydroxyl groups at the edge can survive even at a temperature of 1000°C. 27 It was reported that ether and carbonyl at the edge of graphene are nonmagnetic, 36 while hydroxyl passivating the σ bond of the zigzag edge C can preserve the edge states magnetism. 47,48 Especially, as reported by Song et al, zigzag edges with passivated σ bonds can avoid edge reconstruction.…”

“…The reason may be that some oxygen groups convert to the hydroxyl groups at the edge during the annealing. 27,36 The M-T and 1/χ-T curves of GQDs-20 and GQDs-40 are shown in Supplementary Figure S3a 19 g −1 for GQDs, respectively. Clearly, with the increase of the hydroxyl groups, the spin density of the sample increased.…”

Magnetic Properties of a Bottom‐Up Synthesis Analogous Graphene with N‐Doped Zigzag Edges

“…[ 24 ] OH groups of hydroxylated graphene oxide can effectively induce robust magnetic moments and are up to high magnetization of 2.41 emu g −1 . [ 25 ] The saturation magnetization at the surface of graphite samples at room temperature recently was found up to values above 10 emu g −1 . [ 26 ] N-doping can make graphene oxide to be ferromagnetic with a very high magnetization of 1.66 emu g −1 .…”