Theoretical simulation of reduction mechanism of graphene oxide in sodium hydroxide solution

Abstract

Based on a density functional theory simulation, we proposed a reduction mechanism of graphene oxide (GO) under a sodium hydroxide solution containing anions (OH(-)), cations (Na(+)) and neutral H2O molecules as main components. OH(-) anion can interact with hydroxyl in GO and transfer electrons to the graphene sheet, resulting in negatively charged GO, and these electrons obviously lower the barrier of the ring-opening reaction of epoxy. Na(+) cations can be attracted by the negatively charged GO, and this reaction is equivalent to the one between metallic Na and GO. The opened epoxy is reduced with the assistance of Na(+) cation and water molecule. In such a reduction process, NaOH can be viewed as a catalyst and more defects should be formed because of these diffused epoxies on the negatively charged graphene sheet. Our results may be helpful to understand further the nature of the reduction of GO among various reducing agents.

Identification of functional groups and determination of carboxyl formation temperature in graphene oxide using the XPS O 1s spectrum

“…To do so, GO was reacted with sodium hydroxide (NaOH) and the assignments confirmed by comparing the resulting O 1s spectra. Studies have shown that adding NaOH to GO can cause epoxide ring opening at temperatures as low as 313 K and as a result of this, either ionic oxygen or a hydroxyl would be formed [32,33]. Another study found that the addition of NaOH to aqueous GO resulted in structural damage and decomposition of the carbon lattice [34].…”

“…5(d). This meant that either the concentration of hydroxyl groups in GO was less than 0.10 M or NaOH was acting as a catalyst as proposed by Chen et al [33].…”

Efficient loading of silver nanoparticles on graphene oxide and its antibacterial properties

“…GO contains polyaromatic structure and a variety of oxygen functional groups as epoxy, hydroxyl, carbonyl, and carboxyl. The epoxy groups of GO change into phenolic hydroxyl groups by ring opening reaction in alkaline condition [28]. Furthermore, the carboxyl groups ionize H + under alkaline conditions, making GO negatively charged, which may increase the spaces of the nanosheets by charge repulsion and be more favorable for [Ag(NH 3 ) 2 ] + intercalation and attaching to the GO nanosheets.…”

Alternately Dipping Method to Prepare Graphene Fiber Electrodes for Ultra-high-Capacitance Fiber Supercapacitors

“…The Raman spectrum of the AD:Ti@RGO ( Figure 1 F) shows two peaks around 1,340 and 1,580 cm −1 that are assigned to the D and G bands of carbon, respectively Kudin et al., 2008 , with an I D /I G value of 1.4, which is greater than that of RGO in previous reports Cao et al., 2013 . With the same starting GO solution, DC:Ti@RGO shows an I D /I G value of only 1.1 ( Figure S3 ), indicating that the strong alkaline NaOH solution used in the AD approach may be responsible for the high population of defects ( Chen et al., 2014a ).…”

“…Zhang et al. have theoretically predicted that more defects may be generated on RGO in the presence of NaOH due to the diffusion of epoxies on the negatively charged graphene sheet ( Chen et al., 2014b ).The defects in RGO may induce pores, leading to increased charge-storage capability ( Zhu et al., 2016 ). To verify the impact from strongly alkaline environment, AD:Ti@RGO fibers made in different coagulating and reducing solutions, including CaCl 2 , NaOH, KOH, and ethanediamine, are compared ( Figure S21 ).…”