查看更多>>摘要：? 2021In this paper, a dual-band tunable perfect plasmon absorber based on graphene split-ring-resonator is proposed. The device is composed of resonant ring graphene with an open top layer, a thick PMMA spacer layer and a Cu substrate mirror layer, which has simple structural characteristics. By FDTD simulation method, the numerical results show that perfect absorption is achieved at resonance wavelengths λA = 39.30 μm and λB = 62.00 μm, and the absorption rates are 99.55% and 99.64%, respectively. By adjusting the geometric parameters of graphene array, changing the structural period P and PMMA dielectric thickness, the absorber can achieve perfect absorption. In addition, the resonance wavelength and absorption peak of the absorber can be effectively tuned by controlling the chemical potential, relaxation time and dielectric constant inside the absorber. At last, we exposed the structure to different environmental refractive indices, and calculated the corresponding maximum sensitivities of the two resonant modes as SA = 13.82 μm/RIU and SB = 21.47 μm/RIU. The maximum figure of merit are FOM1 = 4.4870 RIU?1 and FOM2 = 3.5148 RIU?1 respectively. Therefore, the design of graphene-based tunable perfect metamaterial absorber proposed in this study can be applied to photodetectors, sensors and other fields.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, carbon nanotubes (CNTs) are grown by easy method with organic solutions upon foamed nickel substrates. It is found that ethanol is most likely to grow higher quality CNTs than other organic solutions without deoxidation gas. The foamed nickel not only acted as substrates but also uesed as catalyst to grow CNTs and then formed good electrical and thermal contact with CNTs. Moerover, the foamed nickel has intrinsic low contact resistance with CNTs and their multistage structure also makes it as multifunctional electrode for electrical devices. With multistage and high enhancement factor, these CNTs grown on foamed nickel have better field emission properties with turn-on field at 1.4 V/μm and the threshold-field at 2.9 V/μm. With high specific surface area, it is also has high sensitive property to detect heavy metal ion such as Pb2+. The results show it has a good linear relationship exists in the range of 100–400 ppb, and the limit of detection is about 0.955 μg/L Pb2+.This easy CNTs growth method offers a potential application in making field emission electron source and other electrical electrodes.
查看更多>>摘要：? 2021Graphene adsorbents are widely applied in pollutant removal with high adsorption capacities. However, the contradiction between high capacity and poor regeneration hinders the practical applications of graphene adsorbents in aqueous systems. In this study, we designed a magnetic Fe3O4/TiO2/graphene sponge (MFTGS) for dye adsorption in aqueous solution. Small Fe3O4 and TiO2 nanoparticles were decorated on the graphene sheets. MFTGS could be magnetically separated in aqueous systems with a saturated magnetization of 17.0 emu/g. MFTGS showed a moderately large capacity of 224 mg/g for methylene blue (MB). The adsorption could reach the equilibrium within 10 min with a k2 constant of 4.48 × 10?4 g/mg?min?1. The adsorption of MB on MFTGS was driven by entropy production, so the capacity increased at higher temperature. The decrease of pH value and increase of ionic strength slightly lowered the adsorption capacity of MFTGS. MFTGS could be easily regenerated by ethanol washing, where 80% of the capacity retained after 4 cycles. Our results provided high-performance magnetic graphene adsorbents for dye removal and would benefit the development of graphene nanotechnology.
查看更多>>摘要：? 2022 Elsevier B.V.The use of {113} oriented single crystal diamond substrates has been reported for CVD growth of high-quality p-type layers with increased doping efficiency, compared to the {100} orientation, and excellent electrical properties. In this work we expand the range of crystal orientations to include the {118} and {115} planes and study the effect of B doping level in the gas phase with B/C ratios from 250 up to 2000 ppm. We demonstrate the growth of high-quality B doped SCD layers, with low RMS roughness (<2 nm) and high surface chemical purity (99% C with >1% B) for all orientations. Boron incorporation is shown to be dependent not only on the B/C in the gas phase, but also on the crystallographic orientation, with orientations with a higher density of {100}/{111} steps and risers exhibiting higher B incorporation into the solid from the gas phase (4 × 1019 cm?3 up to 1 × 1021 cm?3). Finally, using electro-chemical techniques, we confirm, for the first-time, high-quality electrodes on such orientations. Novelty statement: In this work we report, for the first time, MW PECVD of high-quality boron doped diamond layers on vicinal {118} and {115} single crystal substrates, which are confirmed, via electro- chemical characterisation, to be excellent electrodes.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, efficient ZnWO4 nanotubes incorporated/BC sheets hybrid photoanodes were designed by controlling the surface charges of the two individual materials via facile hydrothermal method. The prepared hybrid nanocomposites have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, photoluminescence (PL) and UV–Visible spectroscopy. XRD and TEM results suggest that monoclinic crystalline structure with 10–15 nm diameter of ZnWO4 nanotubes were uniformly decorated on the outer surface of BC sheet. The BC layer has had a significant impact on the structure and properties of the material, including lattice extension, band-gap reduction, fluorescence enhancement, and photovoltaic activity. The photovoltaic properties of dye-sensitized solar cells were investigated by applying them on the working electrodes. The developed ZnWO4/BC photoanode demonstrated high power conversion efficiency (7.61%), IPCE (78.21%), and long-term stability. The improved mechanism of the proposed photoanode materials are also discussed in detail.
查看更多>>摘要：? 2022 Elsevier B.V.We investigated phase transitions in diamond under cyclic loading near the graphite-diamond equilibrium line at temperatures sufficiently below the Debye temperature (maximum stresses and temperature in the diamond do not exceed 6 GPa and 420 K accordingly). Using Raman and transmission electron microscopy, we reveal the following stages of the transition of diamond to graphite-type phase (onions). The first stage is the plastic deformation by the mechanical twinning along with martensitic phase transition of diamond to intermediate carbon phase (ICP). The next stage is the transition of ICP to onions with a radius below ~5 nm. The proposed theoretical ICP model based on the crosslinking of graphene layers by Frenkel defects displays not only good agreement with the available structural experimental data but also specific properties like enhanced out-of-plane stiffness and metallicity.
查看更多>>摘要：? 2022 Elsevier B.V.The diamond joints of the diamond/CuSnTiGa solder system were prepared under the holding time of 3 min, 6 min, 9 min, 12 min, and 15 min, respectively. The effect of brazing holding time on the microscopic morphology, interface characteristics, element distribution changes and mechanical properties of brazing diamond was studied. When the holding time is 6 min, a continuous and uniform TiC reaction layer has been formed at the interface. Etching of diamond and XRD results both proved the formation of TiC. The microhardness results show that when the holding time is 6 min, the maximum hardness at the interface is 318 HV0.1, and the uniformly fluctuating friction coefficient and grinding removal amount are obtained at the holding time of 6 min. Finally, combined with the analysis of the worn surface morphology, the interface reaction of the base brazing filler metal is closely connected, and the filler metal has a high holding force on the diamond. The 6 min heat preservation can effectively improve the bonding strength and wear resistance of the filler metal and the diamond, and meet the expected use requirements.
查看更多>>摘要：? 2022 Elsevier B.V.To clarify the nature of defects presented in neutron (n)-irradiated highly oriented pyrolytic graphite (HOPG), in situ X-ray diffraction (XRD) observation at room temperature (RT) and high pressure was conducted with synchrotron radiation (SPring-8). We focused on the graphite (002) [G(002)] peak under compression to 18.1 GPa and also under decompression. For comparison, unirradiated HOPG was also placed in the same high-pressure cell. We found that the G(002) peak can be represented by two components, the S and L peaks, for the n-irradiated HOPG, whereas it can be represented by only one component for the unirradiated HOPG. The d-spacing for the n-irradiated and unirradiated HOPG samples gradually decreased with increasing pressure. At 18.1 GPa, the d-spacing of the S peak of the irradiated sample became almost the same as that of the unirradiated one, but that of the L peak was larger. Under decompression, the behavior of the d-spacing was almost opposite to that under compression, and the d-spacing was restored to its value before compression. Also, taking account of the changes in the peak widths, we referred to and considered irradiation-induced defects of interstitial-type defects existing between the basal planes and in-plane defects of dislocation dipoles as possible defects that affect the changes in the G(002) peak.
查看更多>>摘要：? 2022 Elsevier B.V.Laser ablation is an effective and advantageous dressing method for dressing diamond grinding wheels. Previously, research on laser dressing has focused on parallel and convex face diamond wheels. Studies of the laser dressing model analysis and the sources of shape error for concave diamond wheels are less numerous. There is no research to analyse the source of the diamond wheel error from the optics itself. In this paper, a novel deflectable dual-laser misaligned tangential (DDLMT) dressing method was proposed for processing concave rectangular bronze-bonded diamond wheels. Using the DDLMT process, the slope effect error in dressing concave rectangular diamond wheels was basically eliminated. To analyse the causes of the slope effect error during profiling, a theoretical study of the laser radial and tangential dressing methods was carried out, and a mathematical model was established to analyse the laser energy loss mechanism. Experiments on different positions dressings were conducted to validate the mathematical model. The DDLMT dressing method offered a significant improvement in contour accuracy and more than doubled the dressing efficiency compared to single beam profiling. As the laser deflection angle increased, the angle deviation of the dressed right-angle contour gradually decreased. The least deviation of right-angle profile obtained was 0.51° when the deflection angle was 5°. The final PV value of the bottom contour was 11.83 μm, which had a better contour accuracy. The surface quality of the grinding wheel by DDLMT dressing is far better than that of radial dressing. The experimental results demonstrated the potential of the DDLMT dressing method for precision profiling diamond wheels.
查看更多>>摘要：? 2022 Elsevier B.V.There is still an urgent need to develop photothermal agents (PTAs) with stable photothermal stability and good biocompatibility, especially PTAs with functional groups for mild-temperature photothermal therapy (PTT). Herein, carboxylated nanodiamond (ND-COOH) was prepared by annealing of pristine nanodiamond (ND), and aminated nanodiamond (ND-PEI) was further synthesized by grafting ethylenediamine-branched polyethylenimine to ND-COOH. The mild-temperature photothermal effect of these NDs was certified. The photothermal conversion efficiency of the NDs was calculated to be ~20%, and the photothermal properties were stable for the NDs with the functional groups, which supplies possibility to further modify NDs as mild-temperature photothermal nanoplatforms. In vitro antibacterial experiments showed that almost all of the bacteria (>99%) co-cultured with NDs at concentration of 200 μg/mL and 150 μg/mL to S. aureus and to E. coli were killed after 808 nm irradiation for 10 min, respectively. 4T1 cells, mouse breast cancer cells, co-cultured with 200 μg/mL NDs under irradiation 10 min were ablated about 40%. Meanwhile, NDs showed no cytotoxicity and excellent biocompatibility. Therefore, NDs can be used as mild-temperature PTAs by near-infrared light-triggering, and NDs with functional groups will be new promising nanoplatforms which may inspire many new progresses in the field of mild-temperature PTT.
NSTL
Elsevier