López-Dı Az David, Merchán M Dolores, Velázquez M Mercedes, Maestro Armando
Departamento de Quı́mica Fı́sica, Facultad de Ciencias Quı́micas, Universidad de Salamanca, 37008 Salamanca, Spain.
Institut Max von Laue and Paul Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble, cedex 9, France.
ACS Appl Mater Interfaces. 2020 Jun 3;12(22):25453-25463. doi: 10.1021/acsami.0c05649. Epub 2020 May 21.
We address here the role of oxidation impurities on the structure of graphene oxide films at the air-water interface by specular neutron reflectivity (SNR). We study films of purified graphene oxide (PGO) and nonpurified graphene oxide in the close-packed state. Nonpurified graphene oxide is constituted by graphene oxide (GO) layers with oxidation impurities adsorbed on the basal plane, while in PGO sheets, impurities are eliminated. SNR measurements show that GO films are formed by well-defined bilayers constituted by 2-3 layers of GO stacked in contact with air and a second layer of impurities submerged in the aqueous subphase. In contrast, PGO films are formed by a single layer in contact with air. We show for the first time that impurities constitute a layer submerged in the aqueous subphase, decrease the elasticity, and favor the collapse of graphene oxide films. Our results allow designing the surface properties of GO trapped at fluid interfaces.
我们通过镜面中子反射率（SNR）研究了氧化杂质在空气-水界面处对氧化石墨烯薄膜结构的作用。我们研究了紧密堆积状态下的纯化氧化石墨烯（PGO）薄膜和未纯化氧化石墨烯薄膜。未纯化氧化石墨烯由氧化石墨烯（GO）层构成，其基面吸附有氧化杂质，而在PGO薄片中，杂质被去除。SNR测量表明，GO薄膜由明确的双层组成，该双层由与空气接触堆叠的2 - 3层GO以及浸没在水相下层的第二层杂质构成。相比之下，PGO薄膜由与空气接触的单层组成。我们首次表明，杂质构成浸没在水相下层的一层，会降低弹性，并有利于氧化石墨烯薄膜的塌陷。我们的结果有助于设计捕获在流体界面处的GO的表面性质。
