Estimating hydroxyl/epoxy ratio in graphene oxide through adsorption experiment and semiempirical GFN2-xTB quantum method

Larissa C A Souza; Regis V A Abreu; Mário C Guerreiro; Juliano E Oliveira; Cleber P A Anconi

doi:10.1007/s00894-023-05444-4

Estimating hydroxyl/epoxy ratio in graphene oxide through adsorption experiment and semiempirical GFN2-xTB quantum method

J Mol Model. 2023 Jan 18;29(2):42. doi: 10.1007/s00894-023-05444-4.

Authors

Larissa C A Souza¹, Regis V A Abreu¹, Mário C Guerreiro¹, Juliano E Oliveira², Cleber P A Anconi³

Affiliations

¹ Department of Chemistry, Institute of Natural Sciences, University of Lavras, Lavras, 37200900, Brazil.
² Department of Engineering, School of Engineering, University of Lavras, Lavras, 37200900, Brazil.
³ Department of Chemistry, Institute of Natural Sciences, University of Lavras, Lavras, 37200900, Brazil. cleberanconi@ufla.br.

PMID: 36653546
DOI: 10.1007/s00894-023-05444-4

Abstract

Context: The reactivity of graphene oxide (GO) with amines is related to the ring-opening of the epoxy groups in its basal surface, as addressed experimentally. Therefore, discussing the hydroxyl/epoxy ratio for GO is relevant to improve the characterization of such material. As the adsorption of Methylene Blue into GO is related to a graphene derivative's oxidation degree (OD), we combined adsorption experimental information and theoretical data to estimate the hydroxyl/epoxy ratio. The theoretical data were compared to the experimental adsorption of Methylene Blue and Indigo Carmine into GO synthesized in our department. Our results show GO systems with hydroxyl/epoxy ratios equal to 0.7, 0.8, and 0.9 are the most representative in which the most coherent model corresponds to OH/EP=0.8 for our GO previously synthesized.

Methods: The GO-MODEL software was developed in the present work to obtain cartesian coordinates of GO systems. We investigated 204 systems comprising models with 486 carbon atoms with the GFN2-xTB semiempirical quantum method. The supramolecular arrangements were constructed with the recently developed UD-APARM program.

Keywords: Adsorption; Epoxy/hydroxyl ratio; GFN2-xTB; Graphene oxide; Methylene Blue.