Graphene Oxide: Study of Pore Size Distribution and Surface Chemistry Using Immersion Calorimetry.

Carlos A Guerrero-Fajardo,Juan Carlos Moreno-Piraján,Liliana Giraldo

doi:10.3390/nano10081492

Carlos A Guerrero-Fajardo, Juan Carlos Moreno-Piraján + Show 1 more

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https://doi.org/10.3390/nano10081492

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Abstract

In this work, the textural parameters of graphene oxide (GO) and graphite (Gr) samples were determined. The non-local density functional theory (NLDFT) and quenched solid density functional theory (QSDFT) kernels were used to evaluate the pore size distribution (PSD) by modeling the pores as slit, cylinder and slit-cylinder. The PSD results were compared with the immersion enthalpies obtained using molecules with different kinetic diameter (between 0.272 nm and 1.50 nm). Determination of immersion enthalpy showed to track PSD for GO and graphite (Gr), which was used as a comparison solid. Additionally, the functional groups of Gr and GO were determined by the Boehm method. Donor number (DN) Gutmann was used as criteria to establish the relationship between the immersion enthalpy and the parameter of the probe molecules. It was found that according to the Gutmann DN the immersion enthalpy presented different values that were a function of the chemical groups of the materials. Finally, the experimental and modeling results were critically discussed.

Highlights

The materials area is one of the most studied in science today, due to its wide spectrum of applications
The results presented so far showed that the average pore width calculated by quenched solid density functional theory (QSDFT) indicated small pore values, around 7.80 nm to 8.75 nm for Gr and graphene oxide (GO) respectively, which confirmed the structural change of Gr as starting component to obtain GO
To analyze the results of the immersion enthalpy obtained with the probe molecules based on the pore size distribution (PSD), only the area corresponding to the porous micro-meso was considered

Summary

Introduction

The materials area is one of the most studied in science today, due to its wide spectrum of applications. Graphene is characterized by having different properties among which electrical, thermal, and optical can be mentioned This material can be used in areas such as compounding for the electronic industry, thin films, the environment, catalysis, sensors, and biosensors, among others. It is possible to obtain derivatives of it that have different chemical and physical properties useful in what refers to its applications [4,5,6] One of these new materials is graphene oxide (GO), which contains abundant functional oxygen groups such as carboxyl, carbonyl, hydroxyl, and ether in the basal plane of the carbon sheet, which makes the GO intermediate layer hydrophilic and allows it to be subjected to intercalation processes, since it is possible that they are stacked in graphene oxide. GO can be used by taking advantage of its hydrophilic surface, which provides it with a favorable environment for the intercalation of polar organic molecules [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]

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