查看更多>>摘要：? 2022 Elsevier B.V.The effective reduction of graphene oxide (GO) and incorporation of dopant elements on flexible soft substrates, such as plastics, polymers, papers etc. are of significant importance for energy-related devices and flexible wearable electronics. Here, we demonstrate a novel microwave-excited surface-wave plasma (MW-SWP) process to reduce insulating GO to highly conducting reduced graphene oxide (rGO) on the polyethylene terephthalate (PET) substrate as well as achieving reduction of free-standing GO paper at a near-room temperature. It is also observed that the GO coated on the both top and back surface of a PET substrate reduce simultaneously to obtain conducting rGO films. Most effective reduction was achieved using an argon-hydrogen gas mixture, whereas addition of nitrogen in the gas mixture enabled to incorporate nitrogen dopant in the rGO layers. The GO coated PET and freestanding GO films showed a sheet resistance in the range of MΩ/□, which reduced to an average value of 1.075 kΩ/□ and 134 Ω/□, respectively after the plasma treatment. Thus, the developed MW-SWP process can be significant to produce highly conducting rGO-based graphene films on a soft substrate as well as enabling fabrication of highly conducting freestanding rGO papers.
查看更多>>摘要：? 2022The Cerium Phosphate (CP) doped g-C3N4(g-CN) composite was synthesized by a simple hydrothermal process. The crystal nature, absorbance, morphology, elemental analysis, functional groups analysis, charge and particle size of all the synthesized materials were examined by various characterization techniques like UV ? Vis-DRS spectroscopy (UV–Vis),Fourier transform infra red spectroscopy analysis (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy techniques (TEM), zeta potential and particle size analyser. The characterized CP/g-CN composite was used as a photocatalyst for the degradation of malachite green (Mal G) dye under the visible light irradiation with peroxymonosulfate (PMS) activation. The composite material was found to successfully overcome the electron hole recombination process. The PMS activation process was used to enhance the photocatalytic efficiency of the synthesized CP/g-CN composite. The synthesized CP/g-CN with PMS activation exhibits 94% of malachite green dye degradation in time duration of 90 min and also was found to retain 90% of degradation efficiency after four consecutive photocatalytic performances. The toxicity of the photocatalytic degraded water sample was examined by the animal and plant mortality studies. The zebra fish (Danio rerio) and Mung bean (Vigna radiata) were employed in the animal and plant survival investigations. The CP/g-CN photocatalyst treated dye solution is found to be fit for animal and plant survival and therefore it is a potential photocatalyst for water remediation application.
查看更多>>摘要：? 2022In the present research, the influence of nanodiamond (ND) and a physical hybrid of ND and fumed nano-SiO2 were investigated on the performance of a typical tire tread compound. The styrene-butadiene rubber (SBR) and cis-butadiene rubber (BR) blend filled with a commercial grade highly dispersive silica at 70 phr loading were used as typical tire tread compound. ND was substituted partially with silica at two different concentrations of 5 and 10phr. Meanwhile, 5 phr of ND/nano-SiO2 hybrids with the weight ratio of 2.5/2.5 and 1/4 were substituted with silica. ND-Filled compounds exhibit increased scorch and cure time compared to controls. Improvement in different characteristics of the control sample such as mechanical properties, thermal conductivity and crosslink density estimated based on the tube theory and swelling test was observed for 5 phr loading of ND. The sample containing 5 phr loading of ND exhibited improved Young's modulus (～ 40%) and enhanced thermal stability (～ 40°C and ～ 10 °C increase in temperature at weight loss of 10% and 50%, respectively). Moreover, ND at 5phr loading provided notable progress (～ 10%) in wet traction, which could be essential for tire tread manufacturers. ND/nano-SiO2 hybrid enhanced the hardness and thermal stability in synergistic manner.
查看更多>>摘要：? 2022 Elsevier B.V.Recent studies have shown that nitrogen-doped carbon nanotubes (N-CNTs) exhibit anomalous piezoelectric properties, which opens broad prospects for their use in the field of nanopiezotronics. In this work, we have demonstrated the effect of the material of the conducting sublayer (titanium, titanium nitride, molybdenum, and chromium) on the structural and piezoelectric properties of N-CNTs. It was found that the sublayer material significantly affects the nitrogen concentration and the type of defects formed in N-CNTs, which in turn has a decisive effect on the magnitude of the piezoelectric strain coefficient of N-CNTs. It is shown that the maximum piezoelectric strain coefficient is observed for CNTs grown on a molybdenum sublayer, which is associated with the active formation of pyrrolic nitrogen in the nanotube structure in the process of growth. The magnitude of the piezoelectric strain coefficient N-CNTs increases from 5.6 to 21.5 pm/V with an increase in the concentration of pyrrolic nitrogen from 10 to 39%. An increase in the piezoelectric strain coefficient of N-CNTs, in turn, leads to an increase in the generated current from 12 to 138 nA. The results obtained can serve as a basis for the development of energy-efficient nanogenerators based on nitrogen-doped CNTs.
查看更多>>摘要：? 2022 Elsevier B.V.To develop a highly efficient and easily recyclable photocatalysts, graphitic carbon nitride (g-C3N4) nanosheets were hydrothermal synthesized firstly and then magnetic Ni nanoparticles were anchored on g-C3N4 nanosheets with solvothermal method. The morphology, microstructures, magnetic response and photocatalytic activity of all samples were characterized with XRD, TEM, VSM, N2 adsorption–desorption isotherms and spectrophotometer. All results indicate that Ni nanoparticles anchor on the surface of g-C3N4 nanosheets to form Ni/g-C3N4 nanocomposites. The g-C3N4 nanosheets present the higher photocatalytic activity than pristine g-C3N4 powders. The photocatalytic activities to MB and CIP of Ni/g-C3N4 nanocomposites are much higher than those of g-C3N4 nanosheets. The interface between Ni and g-C3N4 forms the metal-semiconductor heterojunctions, which plays a dominated role on electron transition near interface. The photogenerated electrons near interface prefer to transfer from g-C3N4 nanosheets to Ni nanoparticles, resulting in the separation of photogenerated electron-hole pairs. Furthermore, Ni/g-C3N4 nanocomposites could be easily separated from the solution after photocatalysis.
查看更多>>摘要：? 2022It is meaningful that the sensing performance is achieved in a simple graphene structure. In this paper, we proposed a simple graphene-based metasurface structure which contain a graphene ribbon and U-shaped graphene pattern, showing outstanding sensing performance in terahertz band. The transmission spectrum with three dips is excited in our proposed structure calculated by the finite-difference time domain (FDTD) simulation method. The results show that the transmission spectrum with three dips can be effectively tuned by the Fermi energy. Intriguingly, the tri-frequency detection of the sensing performance is focused on the proposed graphene-based metasurface. The maximum of sensitivity and figure of merit(FOM) for the sensing performance are 3.4269 THz/RIU and 21.92, respectively. These research results may pave the way for the development of optical terahertz sensing devices.
查看更多>>摘要：? 2022 Elsevier B.V.Point defects in diamond are responsible for a wide range of optoelectronic properties, making it crucial to engineer defect concentrations for novel applications. However, considering the plethora of defects in co-doped semiconducting and dielectric materials and the dependence of defect formation energies on heat treatment parameters, process-design based on an experimental trial and error approach is not an efficient strategy. This makes it necessary to explore computational pathways for predicting defect equilibria during heat treatments. By considering nitrogen, hydrogen, and silicon doped diamond, we have investigated the pressure dependence of defect formation energies and calculated the defect equilibria during heat treatment of diamond through ab-initio calculations. We have plotted monolithic-Kr?ger-Vink diagrams for various defects, representing defect concentrations based on process parameters, such as temperature and partial pressure of gases used during heat treatments of diamond. The method demonstrated predicts the majority of experimental data, such as nitrogen aggregation path leading towards the formation of the B center, annealing of the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal stability of the SiV center, and temperature dependence of NV concentration. We demonstrate the possibility of designing heat treatments for diamond and other semiconducting or dielectric materials through ab-initio modeling of defect equilibria.
查看更多>>摘要：? 2022 Elsevier B.V.A friction experiment was carried out after the high-temperature annealing of polycrystalline diamond compact (PDC) with cobalt removal and unused grinding balls. The annealing process was carried out in a box-type resistance furnace. The PDC after high-temperature annealing for cobalt removal was studied by scanning electron microscopy, energy-dispersive X-ray spectrometry, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The results of atomic force microscopy showed that the roughness of ZrO2 after grinding with PDC was the lowest among the three friction pairs that were studied, and it exhibited excellent tribological properties. The experimental results showed that different tribochemical mechanisms operated between the unused grinding balls and PDC. The results of XPS analysis showed that oxygen and tungsten ions caused strong chemical oxidation, and the tungsten carbide (WC) friction pair thus exhibited severe friction and wear. The sp3 structures in PDC were transformed into sp2 structures in different friction pairs, and finally a dynamic equilibrium was achieved. Therefore, different friction and wear mechanisms operated in PDC in different friction pairs. These experimental data can promote, by providing a theoretical basis, the use of PDC in friction pairs in actual engineering applications.
查看更多>>摘要：? 2022The recent observations of unusual ferromagnetic and superconductive phenomena in sulfur-doped amorphous carbon and highly oriented pyrolytic graphite (HOPG) have attracted significant attention. In this work we present a novel in-depth investigation on the relationship between magnetic-ordering and sulfur-doping-induced structural modifications in pyrolytic graphite. We demonstrate the nucleation of an unusual amorphous carbon film with sp3-rich characteristics as a result of chemical interactions between sulfur and HOPG. Investigations were performed at the controlled temperatures (T) of ~300, 350, 500 °C, with the residence time parameter varying from 1 min to 15 h. Magnetic characterization revealed a re-entrant spin-glass behavior, possibly originating from vacancy-defects created by sulfur migration. Noticeably, long-time air-exposure of the samples (3 weeks) was found to significantly enhance the diamagnetic component. Density functional theory (DFT) calculations applied to a sp3-rich amorphous?carbon-system in presence of sulfur-bonding revealed a significant variation of the system-metallicity. We report the presence of insulating states up to sulfur concentrations of ~6.25% (atom %), which then vanish at ~7.5% (atom %) of sulfur-doping. Interestingly, inclusion of the sulfur-migration effect within the DFT calculations revealed significant contributions arising from magnetic-moments generated by electron localization at the vacancy sites. Total spin isosurface analyses (spin up - spin down) highlighted the presence of ferromagnetic contributions arising from carbon-atoms, due to dangling bonds generated by point defects (with the largest magnetic moment values being 0.42 μΒ and 0.379 μΒ respectively).
查看更多>>摘要：? 2022 Elsevier B.V.We studied theoretically the interactions of phthalocyanines (Pcs) of general formula MPc (M = 2H, Mn, Fe, Co, Ni, Cu, Zn) with endohedral fullerenes (EFs) N@C60 and P@C60, at the PBE-D/DNP theoretical level. All MPcs can form stable noncovalent complexes with both N@C60 and P@C60. The binding energies vary between ?17.7 and ?31.1 kcal/mol. Complexation pattern depends on the central atom of MPc, but not on the endohedral species (N or P): for H2Pc, two central H atoms approach the carbon atoms of C60 of adjacent 5:6:6 junctions; for MnPc, manganese atom coordinates to two carbon atoms of 6,6 C-C bond; for other MPcs, the central metal coordinates to 5:6:6 junction of fullerene. In MPc+N@C60 HOMO is localized exclusively on phthalocyanine, with LUMO found mostly on fullerene. In MPc+P@C60 complexes, HOMO has essentially the same localization and shape, but LUMO distribution is variable. After complexation with MPcs, no tangible changes are observed in the N and P spin state. MnPc, CoPc and CuPc having open-shell metal atoms behave differently: while the complexation has almost no effect on Cu spin, and causes only a moderate decrease in Co spin, Mn atom transfers roughly two-thirds of its unpaired electrons to fullerene.
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