No abstract

Understanding the mechanism of adsorption and self-assembly of surfactants on graphene is highly important to perform better optimization of the graphene dispersion process. Because of Gemini surfactants' special structure, they have a high charge capacity, high hydrophobicity, and unique self-assembly properties compared to single-chain surfactants. Therefore, Gemini surfactants with their small concentrations are expected to disperse and stabilize graphene nanosheets in aqueous solutions more effectively. We conducted molecular dynamics simulations to study adsorption and self-assembly of single-chain cationic surfactant dodecyltrimethylammonium bromide (CTAB) and its same family Gemini surfactant dimethylene-α,β-bis(dodecyldimethylammonium bromide) ([12-2-12]Br) on graphene nanosheets. The results showed that assemblies morphology formed on graphene is affected by surfactant structure. We observed that increasing surface coverage, especially for [12-2-12]Br, leads to a transmission in adsorption mechanism and most [12-2-12]Br head groups tend toward the aqueous phase and prevent water molecules from accessing graphene surface. It can be concluded from morphological assessments that [12-2-12]Br is more effective than CTAB in stabilizing graphene aqueous suspensions. Moreover, we investigated the effect of graphene sheet size and Gemini surfactant spacer length on the structure of surfactant assemblies on graphene. The present study results can expand our comprehension of dispersion mechanism of graphene nanosheets by Gemini surfactants.

A copper (II) supramolecular coordination complex formulated as [Cu2(μ‐ox)2(pyz)3]n (1), (pyz = pyrazine and ox = oxalate) has been synthesized under ultrasound irradiation. 1 was characterized using various techniques such as elemental analyses, Fourier‐transform infrared spectroscopy (FT‐IR), ultraviolet–visible spectroscopy (UV–Vis), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and single crystal X‐ray diffraction (SC‐XRD). A detailed magnetic characterization of complex 1 has been carried by vibrating sample magnetometer (VSM). The M‐H hysteresis loop of 1 revealed a weak ferromagnetic behavior with the highest magnetization of 0.0123 emu/g at room temperature. Compound 1 was used as an inorganic precursor to prepare Cu2O nanoparticles through thermal decomposition at 600 °C. The obtained Cu2O has been characterized using Fourier transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The results of SEM showed octahedron Cu2O nanoparticles with the edge lengths from 5–80 nm. Also, the adsorption ability and the photocatalytic activity of octahedral Cu2O nanoparticles in the removal of rhodamine B (RB) have been investigated. The results showed that the obtained octahedral Cu2O nanoparticles are effective in adsorption and degradation of rhodamine B from contaminated water sources. The maximum adsorption capacity and degradation efficiency of Cu2O nanoparticles were 83.3 mg/g and 91.7%, respectively. It was also found that in comparison with the commercial Cu2O, our fabricated Cu2O nanoparticles exhibit higher catalytic activity.