Calcium incorporation in graphene oxide particles: A morphological, chemical, electrical, and thermal study

• Published in: Thin solid films Vol. 610; pp. 10 - 18
• Main Authors: Castro, Kelly L.S., Curti, Raphael V., Araujo, Joyce R., Landi, Sandra M., Ferreira, Erlon H.M., Neves, Rodrigo S., Kuznetsov, Alexei, Sena, Lidia A., Archanjo, Braulio S., Achete, Carlos A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2016
• Subjects: Calcium; Calcium carbonate; Calcium intercalation; Diffraction; Graphene; Graphene oxide; Hummers' method; Morphology; Oxides; Reduction; Thermal stability; X-ray diffraction; X-ray photoelectron spectroscopy; X-rays; X-ray diffraction; Graphene oxide; Hummers' method; Calcium intercalation; X-ray photoelectron spectroscopy; Thermal stability
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2016.04.042

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.
•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.