Universal Strategy for Reversing Aging and Defects in Graphene Oxide for Highly Conductive Graphene Aerogels

Abstract

The production of highly stable, defect-free, and electrically conducting 3D graphene structures from graphene oxide precursors is challenging. This is because graphene oxide is a metastable material whose structure and chemistry evolve due to aging. Aging changes the relative composition of oxygen functional groups attached to the graphene oxide and negatively impacts the fabrication and properties of reduced graphene oxide. Here, we report a universal strategy to reverse the aging of graphene oxide precursors using oxygen plasma treatment. This treatment decreases the size of graphene oxide flakes and restores negative zeta potential and suspension stability in water, enabling the fabrication of compact and mechanically stable graphene aerogels using hydrothermal synthesis. Moreover, we employ high-temperature annealing to remove oxygen-containing functionalities and repair the lattice defects in reduced graphene oxide. This method allows obtaining highly electrically conducting graphene aerogels with electrical conductivity of 390 S/m and low defect density. The role of carboxyl, hydroxyl, epoxide, and ketonic oxygen species is thoroughly investigated using X-ray photoelectron and Raman spectroscopies. Our study provides unique insight into the chemical transformations occurring during the aging and thermal reduction of graphene oxide from room temperature up to 2700 °C.

Ultra-broadband THz absorbers based on 3D graphene

“…400 • C, 750 • C, and 1300 • C, to produce a 3D GA. The sample annealing affected the GA composition by removing the oxygen-related functional groups [28]. The content of C reached almost ∼100% after the annealing at 1300 • C. A scheme of the fabrication process is depicted in supplementary material (figure S1).…”

Flexible Humidity Sensor Based on a Graphene Oxide–Carbon Nanotube-Modified Co3O4 Nanoparticle-Embedded Laser-Induced Graphene Electrode

“…3 Two-dimensional graphene oxide (GO) features an extensive surface area, an abundance of oxygen-functional groups, and exceptional permeability to water molecules. 22,23 This inherent humidity sensitivity endows it with the potential to significantly improve the sensing performance of humidity sensors. 24 However, the inherent two-dimensional nature of GO engenders a propensity for stacking, thereby diminishing its effective interaction with water molecules and impeding the complete realization of its humidity sensing capabilities.…”