用NMR研究洋葱碳吸附水后的抗磁性（英文）

Diamagnetism of carbon onions probed by NMR of adsorbed water

对洋葱状碳缺陷位吸附水分子的1H化学位移进行测试,并比较块状水和石墨烯、氧化石墨烯和纳米金刚石吸附水的化学位移。纳米金刚石和氧化石墨烯绝缘体的1H共振位置与块状水接近,然而石墨烯和洋葱碳吸附水呈现明显的化学位偏移,这是由导电的石墨烯片层抗磁屏蔽效应所致。质子的化学位移和抗磁性之间存在显著的相关性。

We measured the 1 H chemical shift of water molecules adsorbed on defect sites of carbon onions and compared it with the shifts of bulk water and water adsorbed by chemically-derived graphene, graphene oxide and nanodiamond. The positions of 1H resonances for insulator nanodiamond and graphene oxide are close to that of bulk water, while water molecules adsorbed by gra-phene, and particularly by carbon onions, reveal a significant deviation in chemical shift from that of bulk water, which can be at-tributed to the diamagnetic screening effect of the conducting graphene layers. This conclusion is supported by a pronounced correla-tion established in our experiments between the proton chemical shifts and diamagnetic contribution to the magnetic susceptibility.