查看更多>>摘要：? 2022A Schottky barrier can enhance the separation of electron-hole pairs and the photocatalytic performance. Herein, CuX/g-C3N4 (CuX/CN) photocatalysts with the Schottky barrier were successfully synthesized by a simple electrostatic adsorption method. The obtained Cu3/CN exhibited higher photocatalytic degradation activity (96.77%) and TOC removal rate (86.97%) toward methylene blue (MB) than pure g-C3N4 (29.04%, 36.48%, respectively). In addition, the Cu3/CN performed well in 4 cycles. The enhanced photocatalytic activity was ascribed to the Schottky barrier at the interface of Cu and g-C3N4. Therefore, the semiconductor g-C3N4 became an electron donor for metal Cu under visible light excitation. The separation efficiency of photogenerated carriers was significantly improved via the Schottky barrier, confirmed by photoluminescence spectra, transient photocurrent response, and electrochemical impedance spectra. In addition, the introduction of Cu broadened the absorption range of visible light. The active radical capture tests displayed that superoxide radicals (?O2?) and holes (h+) were dominant radicals during photocatalytic degradation. This work showed that the Schottky barrier provided a new path for the effective transfer of electrons.
查看更多>>摘要：? 2022 Elsevier B.V.The studies on electrochemical sensing of organics present together at low concentration continue to attract researchers. In the present study, concurrent sensing of acetaminophen (AAP), phenylephrine hydrochloride (PPH) and cytosine (CTS) was attempted and implemented successfully with bismuth vanadate/zirconium dioxide@graphene (BiVO4/ZrO2@graphene) modified glassy carbon electrode. The electroactive nanocomposite (EANC) was characterized by XRD, FTIR, SEM with EDX and RAMAN spectroscopy. Using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), the electrochemical oxidative sensing of AAP, PPH, and CTS was investigated. The electrode exhibited enhanced sensitivity and well separation of signals due to all the three analytes. The analytes showed linear response of 7.5 nM to 255.8 μM, 9.5 nM to 120.1 μM and 10.5 nM to 350.05 μM for AAP, PPH and CTS, respectively, and their detection limit was equal to 6.5, 6.9 and 3.8 μM respectively. The research subsequently succeeded to pharmaceutics and blood serum evaluation of same analytes. The stability of the modified electrode was indeed excellent. As a result, the current electrode material could be a successful one for making a commercial electrochemical sensor sense AAP, PPH, and CTS at the same time.
查看更多>>摘要：? 2022 Elsevier B.V.The significance of reduced graphene oxide (rGO) as an electrode material has been widely explored in lithium?oxygen batteries (LOBs) owing to its extensive surface area, excellent electrical conductivity, good mechanical strength, and chemical stability. However, depending on the synthesis procedures and thermal treatments, the rGO structure might have variable structural and chemical features such as the number of layers, functional groups, and defect structure, affecting the electrochemical activity of the electrodes. In recent years, researchers have attempted to produce rGO sheets by reduction of graphene oxide (GO) for different purposes. Several methods have been reported to obtain rGO, such as unzipping of carbon nanotubes, epitaxial growth, chemical vapor deposition, electrochemical exfoliation of graphite, and chemical reduction of GO. Herein, a green strategy was used to synthesize reduced graphene oxide nanosheets by utilizing extract of Salvia Officinalis leaves. The natural reducing agent was compared with sodium borohydride (NaBH4) and hydrazine (N2H4) as potential toxic reducing agents. Graphene oxide was produced by the modified hummers process and successfully reduced by Salvia O. extract due to the presence of active biomolecules in the plant, which act as reducing agents. The proposed method avoids the use of hazardous and expensive chemicals. The as-prepared rGO materials were applied as cathode materials for LOBs, and their electrochemical performances were evaluated. The results exhibited that the electrode GO reduced by Salvia extract delivered a capacity of 4320 mAh g?1, while rGO reduced by hydrazine and NaBH4 offered specific capacities of 3840 mAh g?1 and 3210 mAh g?1, respectively.
查看更多>>摘要：? 2022The geometric deformation, bonding energies and mechanical properties of graphene-h-BN heterostructures (Gr-h-BN) under the coupling of external field (strain rate and temperature) and internal field (grain boundary (GBs) and nanoholes) were studied by using molecular dynamics and nonlinear mechanics. The results show that GBs and nanoholes will cause the Gr-BN-GBs configuration to deviate from the plane configuration, and produce a saddle shape with positive curvature and negative curvature, and its displacement field diverges with distance. In addition, the presence of GBs and nanoholes leads to a reduction in failure stress, Young's modulus and Von-mises stress. However, the presence of GBs and nanoholes also improves the bending rigidities of two dimensional (2D) materials. The adverse and strengthening effects induced by GBs and nanoholes are strongly dependent on temperature and strain rate. A full study of the built-in distorted stress field generated by the interaction of defects in 2D materials will help us to understand the physical mechanism of the relationship between structure and properties in low dimensions, and even design new applications.
查看更多>>摘要：? 2022 Elsevier B.V.The nanocomposites (NCs) contain a hybrid matrix and reinforcing material that could improve the physicochemical and biological properties of individual compounds. HAP, Cu2O, and GO were prepared separately and combined to fabricate nanocomposite (NCs). The hexagonal symmetry of HAP and the cubic symmetry of Cu2O were confirmed using XRD analysis. The different scanning techniques detected HAP with nanorod shape. The length decreased from 50 to 27 nm. Rv reached 208.4 nm. The effect of the ternary nanocomposite (TNC) against S. aureus and E. coli reached 14.1 ± 1.1 and 13.2 ± 1.2 mm, respectively. Furthermore, the cell viability towards the human cell line is around 103 ± 4%. The enhancement in antibacterial behavior and cell viability confirms the biocompatibility of the TNC to be encouraged for use in biomedical utilizations such as bone regeneration.
查看更多>>摘要：? 2022 Elsevier B.V.We study theoretically how to simultaneously achieve narrowband and broadband light absorption enhancement of monolayer graphene, which is placed on a metallic substrate surface with a periodic array of small holes. By a couple model of double resonances, the narrowband and broadband absorption peaks of monolayer graphene are proven to stem from the hybrid modes of delocalized surface plasmon polartions propagating on the substrate surface and localized magnetic plasmons confined within individual holes. The positions, maxima, and bandwidths of the absorption peaks can be tuned conveniently through changing the hole array period. For an optimized period, the maximum absorption values at the narrowband and broadband peaks are able to reach up to 65% and 85%, respectively. The bandwidth of the narrowband absorption peak can be reduced to only several nanometers, and the bandwidth of the broadband absorption peak can be expanded to tens of nanometers. Our work will be helpful to design graphene-based photoelectric nanodevices whose optical responses are in the visible and near-infrared regions.
查看更多>>摘要：? 2022 Elsevier B.V.Porous carbon microspheres (NPO-PCSs) with a high specific surface area (1769 m2 g?1) and in situ self-doped multiple heteroatoms (N, P, and O) were skillfully fabricated via one-step direct pyrolysis of cross-linked poly(cyclotriphosphazene-co-phloroglucinol) microspheres. The doping carbon structure of NPO-PCSs with intrinsic microporosity promises the potential for the adsorption of cationic and anionic dyes (Methyl Blue and Methyl Orange). Moreover, there is a π-π interaction between the ordered graphite units of NPO-PCSs and the aromatic rings of dye molecules, which promotes the dye adsorption capacity of NPO-PCSs. Meanwhile, these in situ self-doped heteroatoms (N, P, and O) can play as Lewis base and the formed Lewis acid-base interaction improves the adsorption performance of the NPO-PCSs. Additionally, for the large containing oxygen groups of the NPO-PCSs adsorbent, there could be the electrostatic attraction between the NPO-PCSs adsorbent and the dye molecules. As results, the absorptivity of the NPO-PCSs for MB and MO could reach 356 and 281 mg g?1 at 25 °C and pH = 7, respectively. Thus, the high-performance NPO-PCSs versatile adsorbent might have a great potential for practical application in wastewater purification.
查看更多>>摘要：? 2022 Elsevier B.V.This work reports about the study of the structure of films of amorphous diamond-like carbon modified with palladium nanoparticles and synthesized on silicon (100) substrates (a-C <Pdx>). Results of Raman studies indicate the change in the ratio of sp2/sp3 sites depending on the Pd concentration in the carbon films. It was found that palladium nanoparticles affect the formation of carbon bonds and increase the number of sp2 sites, and at concentrations of more than 1 at.%, the film structure becomes graphite-like. In addition, atomic force microscopy methods revealed the effect of palladium on the surface morphology of a-C <Pdx> films and non-uniform distribution of electron density. The size of the particles which form the structure of the a-C <Pdx> films was estimated by using the “threshold method of grains analysis” program.
查看更多>>摘要：? 2022 Elsevier B.V.In the current investigation, molecular dynamics simulations were performed to determine the electromechanical response of multi-layer boron nitride sheets (MLBNSs) with the consideration of different numbers of stacked layers, strain rate (SR), temperature and chirality effects, and fracture behavior subjected to uniaxial tensile tests. We found the stress–strain curves and evaluated the elastic modulus, fracture strain, and maximum tensile strength in the armchair (AC) and zigzag (ZZ) directions of BNSs. We assessed the impact of two parameters (number of stacked layers and chirality effect) on the tensile properties of BNSs by comparing the findings at various temperatures and SRs. In addition, our study reveals that MLBNSs with an odd number of BN layers show piezoelectric behavior, whereas an even number of BN layers do not show piezoelectric behavior. The piezo- and flexo-electric coefficients of MLBNSs depend on the following aspects: (i) they have an inverse relationship with the number of BN layers, (ii) even or odd numbers of BN layers, and (iii) they disappear completely when the number of BN layers exceeds ten. The present investigation motivates us to develop high-performance and lightweight piezoelectric BN-based NEMS such as nanogenerators, sensors, and actuators, as the existing piezoelectric nanomaterials are brittle, heavy, and toxic.
查看更多>>摘要：? 2022In this work, two B-doped pentadiamond systems (named as B6C5 and B7C4) are designed and carefully studied with the aid of Density Functional Theory (DFT) calculations. As an additional reference system, the N-doped pentadiamond C10N is also taken into account in this study. Their structural stabilities are verified from different aspects. These systems can be considered as heavily doped semiconductors. Especially, the B6C5 lattice possesses an inherent indirect band gap of 2.01 eV estimated at HSE06 level. Doping with B-atoms in pentadiamond can not only optimize its band gap, but also expand its absorption region into the visible and near infrared regions. These excellent electronic and optical properties, coupled with their significantly low bulk densities around 2.0 g/cm?2 and fairish mechanical strengthes, make the B6C5 and B7C4 systems to be promising candidates in semiconductor industry and solar utilization fields.
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