Electrochemical Exfoliation of Graphite in Aqueous Sodium Halide Electrolytes toward Low Oxygen Content Graphene for Energy and Environmental Applications.
Jose M MunueraJuan Ignacio ParedesM EnterríaA PagánSílvia Villar RodilM F R PereiraJ I MartinsJose Luis FigueiredoJ L CenisA Martínez-AlonsoJ M D TascónPublished in: ACS applied materials & interfaces (2017)
Graphene and graphene-based materials have shown great promise in many technological applications, but their large-scale production and processing by simple and cost-effective means still constitute significant issues in the path of their widespread implementation. Here, we investigate a straightforward method for the preparation of a ready-to-use and low oxygen content graphene material that is based on electrochemical (anodic) delamination of graphite in aqueous medium with sodium halides as the electrolyte. Contrary to previous conflicting reports on the ability of halide anions to act as efficient exfoliating electrolytes in electrochemical graphene exfoliation, we show that proper choice of both graphite electrode (e.g., graphite foil) and sodium halide concentration readily leads to the generation of large quantities of single-/few-layer graphene nanosheets possessing a degree of oxidation (O/C ratio down to ∼0.06) lower than that typical of anodically exfoliated graphenes obtained with commonly used electrolytes. The halide anions are thought to play a role in mitigating the oxidation of the graphene lattice during exfoliation, which is also discussed and rationalized. The as-exfoliated graphene materials exhibited a three-dimensional morphology that was suitable for their practical use without the need to resort to any kind of postproduction processing. When tested as dye adsorbents, they outperformed many previously reported graphene-based materials (e.g., they adsorbed ∼920 mg g-1 for methyl orange) and were useful sorbents for oils and nonpolar organic solvents. Supercapacitor cells assembled directly from the as-exfoliated products delivered energy and power density values (up to 15.3 Wh kg-1 and 3220 W kg-1, respectively) competitive with those of many other graphene-based devices but with the additional advantage of extreme simplicity of preparation.
Keyphrases
- ionic liquid
- room temperature
- carbon nanotubes
- walled carbon nanotubes
- healthcare
- gold nanoparticles
- primary care
- solid state
- molecularly imprinted
- emergency department
- nitric oxide
- reduced graphene oxide
- oxidative stress
- climate change
- big data
- artificial intelligence
- cell death
- cell proliferation
- risk assessment
- high resolution
- quantum dots
- ion batteries