Submicron carbon-based hybrid nano-pour-point depressant with outstanding pour point depressant and excellent viscosity depressant

We have investigated the effective utilization potential of carbon nanomaterials in the field of pour point depressants, and reported three kind of carbon-based hybrid nano-pour-point depressants with different dimensions. In this paper, poly-α-olefins-acrylate high-carbon ester pour point depressant (PAA-18) was prepared by esterification and polymerization as the basic pour point depressant. Then, the basic pour point depressant PAA18 was modified by solvothermal method with graphene oxide (GO), carbon nanospheres (Cna) and carbon nanotubes (OCNTs). The morphology and structure of the composites were analyzed by SEM, FTIR and XRD. The results showed that PAA18 was successfully in situ polymerized on GO, Cna and OCNTs. We took the simulated oil as the experimental object, and evaluated its pour point, rheological properties and wax crystal morphology, and achieved excellent results. In the three carbon-based hybrid nano-pour-point depressants with different carbon contents, the oxidation carbon nanotubes composite pour point depressant (PAA18-1 % OCNTs) with carbon content of 1 % had the best pour point and viscosity reduction effect when the dosage was 1250 ppm, which could make the pour point of the simulated oil containing wax decrease by 16 °C. PAA18-1 % OCNTs reduced the pour point by 5 °C more than PAA18. This paper provides reference for the application of carbon nanomaterials in the field of pour point depressant.     

Micro-droplet Trapping and Manipulation: Understanding Aerosol Better for a Healthier Environment

Understanding the physicochemical properties and heterogeneous processes of aerosols is key not only to elucidate the impacts of aerosols on the atmosphere and humans but also to exploit their further applications, especially for a healthier environment. Experiments that allow for spatially control of single aerosol particles and investigations on the fundamental properties and heterogeneous chemistry at the single-particle level have flourished during the last few decades, and significant breakthroughs in recent years promise better control and novel applications aimed at resolving key issues in aerosol science. Here we propose graphene oxide (GO) aerosols as prototype aerosols containing polycyclic aromatic hydrocarbons, and GO can behave as two-dimensional surfactants which could modify the interfacial properties of aerosols. We describe the techniques of trapping single particles and furthermore the current status of the optical spectroscopy and chemistry of GO. The current applications of these single-particle trapping techniques are summarized and interesting future applications of GO aerosols are discussed.     

Preparation of quaternarized N-halamine-grafted graphene oxide nanocomposites and synergetic antibacterial properties

At present, frequent outbreaks of bacteria and viruses have seriously affected people's normal lives. Therefore, the study of broad-spectrum antibacterial nanocomposites is very promising. However, most antibacterial materials have some disadvantages, such as single bactericidal mechanisms and unrepeatable use. Based on the current situation, a kind of nanocomposite with three structures of graphene oxide (GO), quaternary ammonium salt (QAs) and N-halamine was prepared, which showed synergistic effect to improve antibacterial activity and combined with a variety of sterilization mechanisms. Meanwhile, GO can provide richer ways of sterilization and high specific surface area, which is conducive to the grafting of quaternarized N-halamine. The advantages of physical sterilization of GO, charge adsorption of QAs, reuse of N-halamine and efficient sterilization are fully utilized. The results showed that the quaternarized N-halamine-grafted GO was obtained successfully. GO grafted with quaternarized N-halamine polymer showed strong speedy bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) (99%). It had good storage and regeneration properties.     

Surface oxidized iron-nickel nanorods anchoring on graphene architectures for oxygen evolution reaction

Surface oxidized iron-nickel nanorods coupling with reduced graphene architectures (FeNi-O-rGA) are successfully constructed via hydrothermal, freeze-drying, and thermal activation approaches. The hierarchical structure can provide lots of pathways for fast ion diffusion and charge transfer, and expose abundant catalytic sites. Meanwhile, the activity of FeNi-O-rGA is boosted by the optimized metal-oxygen bond strength in FeNi₃ alloys. Partial oxidized FeNi nanorods are strongly coupled with rGA by the formation of metal-O-C bonds, which can impede the aggregation of FeNi₃ alloys and increase the utilization of active sites. The special structure and partially oxidized FeNi nanorods for FeNi-O-rGA can result in excellent OER activity and catalytic stability. Only 215 mV of overpotential is required to drive the current density of 10 mA/cm² as well as the Tafel slope of 50.9 mV/dec in 1 mol/L KOH. The change of surface chemistry of FeNi-O-rGA is confirmed by XPS after the OER test, which indicates the highly catalytic stability of FeNi-O-rGA due to the formation of intermediate metal oxyhydroxide.     

Determination of Tedizolid Phosphate Using Graphene Nanocomposite Based Solid Contact Ion Selective Electrode; Green Profile Assessment by Eco-scale and GAPI Approach

Antibiotics determination plays a major role in minimizing antimicrobial resistance starting from quality control of pharmaceutical formulations to therapeutic drug monitoring. Green modified glassy carbon electrode has been developed for determination of tedizolid phosphate; new antibiotic prodrug; in presence of its active metabolite. The graphene transducer interlayer, dispersed with PVC, improved the electrode stability and standard potential reproducibility. Graphene hydrophobicity prevented the water layer formation between the sensing layers that decreased the potential drift down to 267 μV h⁻¹. Electrochemical impedance showed a low resistance value for graphene containing sensor due to its high electron transfer ability.     

Binary Metal Oxide Adsorbed Graphene Modified Glassy Carbon Electrode for Detection of Riboflavin

Tungsten oxide (W) decorated titanium oxide (T) adsorbed onto a graphene (Gr) and modified the glassy carbon electrode for the electrochemical quantification of riboflavin (RF) in edible food and pharmaceuticals. For comparison, nanocomposites are formed using graphene oxide (GO), reduced graphene oxide (rGO) and pure graphite (G) sheets to study the electrochemical activities towards riboflavin. The ternary WTGr modified GCE shows the highest electrocatalytic activity due to synergetic interactions between the metal oxide and graphene. The electrochemical observations are supported by the SEM, HRTEM, XRD, UV-Vis, Zeta potential (ζ) and size data. The sensor shows a wide linear range 20 nM–2.5 μM with a detection limit 25.24 nM and sensitivity (4.249×10⁻⁸ A/nM). The fabricated sensor is validated in real samples.     

Spin and orbital magnetic moments and spin anisotropy energies of light rare earth atoms embedded in graphene: A first-principles study

The geometries, electronic structures, spin magnetic moments (SMMs), orbital magnetic moments (OMMs) and spin anisotropy energies (SAEs) of light rare earth atoms (La, Ce, Pr, Nd, Pm, Sm, Eu, and Gd) embedded in graphene were studied by using first-principles calculations based on Density Functional Theory (DFT). The spin-orbital coupling effect was taken into account and GGA+U method was adopted to describe the strongly localized and correlated 4f electrons. There is a significant deformation of the graphene plane after doping and optimization. The deformation of Gd doped graphene is the largest, while Eu the smallest. The results show that the valence is +3 for La, Ce, Pr, Nd, Pm, Sm and Gd, and +2 for Eu. Except Eu and Gd, there are obvious OMMs. When the spin is in the Z direction, the OMMs are −0.941 μ_B, −1.663 μ_B, −3.239 μ_B, −3.276 μ_B and −3.337 μ_B for Ce, Pr, Nd, Pm and Sm, respectively, and point the opposite direction of SMMs. All the doped systems except Gd show considerable SAEs. For Ce, Pr, Nd, Pm, Sm, and Eu, the SAEs are −0.928 meV, 20.941 meV, −8.848 meV, 7.855 meV, 75.070 meV and 0.810 meV, respectively. When the spin orientation is different, different orbital angular moments lead to apparent charge density difference of the 4f atoms, which can also explain the origin of SAEs.     

Change of the short-range scattering in the graphene covered with Bi2O3 clusters

In this work, we have studied the oxidation process of the bismuth doped graphene in the ambient air. Complete oxidation of the bismuth clusters and that of the graphene are firmly confirmed. The influence of oxygen on the graphene is characterized by means of Hall measurement and SdH oscillation. All transport measurements demonstrate a hole-type doping behavior. Our work also demonstrates that the short-range scattering mechanism is enhanced in doped graphene due to accumulated O-species adsorbates after being exposed in the atmosphere for 40 days and is suppressed after annealing. This investigation may open a new perspective for fabricating the graphene metal oxide devices.     

Reprint of : Shot noise fluctuations in disordered graphene nanoribbons near the Dirac point

Random fluctuations of the shot-noise power in disordered graphene nanoribbons are studied. In particular, we calculate the distribution of the shot noise of nanoribbons with zigzag and armchair edge terminations. We show that the shot noise statistics is different for each type of these two graphene structures, which is a consequence of the presence of different electron localizations: while in zigzag nanoribbons electronic edge states are Anderson localized, in armchair nanoribbons edge states are absent, but electrons are anomalously localized. Our analytical results are verified by tight binding numerical simulations with random hopping elements, i.e., off diagonal disorder, which preserves the symmetry of the graphene sublattices.     

Electronic and magnetic behaviors of graphene with 5d series transition metal atom substitutions: A first-principles study

The electronic structures and magnetic behaviors of graphene with 5d series transition metal atom substitutions are investigated by performing first-principles calculations. All the impurities are tightly bonded to single vacancy in a graphene sheet. The substitutions of La and Ta lead to Fermi level shifting to valence and conduction band, respectively. Both the two substitutions result in metallic properties. Moreover, the Hf, Os and Pt-substituted systems exhibit semiconductor properties, while the Re and Ir-substituted ones exhibit robust half-metallic properties. Interestingly, W-substituted system shows dilute magnetic semiconductor property. On the other hand, the substitution of Ta, W, Re and Ir induce 0.86 μ_B, 2 μ_B, 1 μ_B and 0.99 μ_B magnetic moment, respectively. Our studies demonstrate that the 5d series transition metal substituted graphene have potential applications in nanoelectronics, spintronics and magnetic storage devices.