| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1663958 | Thin Solid Films | 2016 | 9 Pages |
•Graphene oxide has been chemically modified with Ca ions by immersion in a CaCO3 solution.•GO–Ca has morphology similar to an ultra-thin membrane composed of overlapping sheets.•CaCO3 residue was completely removed by acid washes, leaving only ionic calcium.•EDS maps show that Ca incorporation is spatially homogeneous in GO structure.•Thermal analyses show a remarkable increase in GO stability after Ca incorporation.
Surface chemical modification and functionalization are common strategies used to provide new properties or functionalities to a material or to enhance existing ones. In this work, graphene oxide prepared using Hummers' method has been chemically modified with calcium ions by immersion in a calcium carbonate solution. Transmission electron microscopy analyses showed that graphene oxide (GO) and calcium incorporated graphene oxide have a morphology similar to an ultra-thin membrane composed of overlapping sheets. X-ray diffraction and Fourier-infrared spectroscopy show that calcium carbonate residue was completely removed by hydrochloric acid washes. Energy dispersive X-ray spectroscopy mapping showed spatially homogeneous calcium in Ca-incorporated graphene oxide sample after HCl washing. This Ca is mainly ionic according to X-ray photoelectron spectroscopy, and its incorporation promoted a small reduction in the graphene oxide structure, corroborated also by four-point probe measurements. A thermal study shows a remarkable increase in the GO stability with the presence of Ca2 + ions.
