查看更多>>摘要：Herein, the capability of glutaraldehyde cross-linked magnetic chitosan nanoparticles (Fe3O4/CS/GA NPs) was investigated as a heterogeneous electro-Fenton catalyst for the degradation of Acid Blue 25. A cylindrical reactor with rotating cathodes was used for performing the electro-Fenton process. Fe3O4/CS/GA NPs were characterized by Fourier-Transform Infrared Spectroscopy (FT-IR), X-ray Powder Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray (EDX), and Vibrating Sample Magnetometer (VSM). According to the results, the dye removal efficiency reached 94.83% after 90 min under the optimal conditions of Fe3O4/CS/GA NPs with the iron content of 15 mmol Fe/g chitosan and concentration of 0.3 g/L, natural pH of dye (6.8), initial dye concentration of 150 mg/L, the current intensity of 0.7 A, and rotational speed of 100 rpm. Also, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removal reached 74.19% and 61.53% after 120 min, respectively. Average oxidation state (AOS) and carbon oxidation state (COS) values were increased after treatment, indicating that wastewater's biodegradability was improved. Moreover, the heterogeneous electro-Fenton process using optimal Fe3O4/CS/GA NPs resulted in about 16% improvement in the removal efficiency compared to the homogeneous process. The catalyst showed good reusability up to 5 cycles. The amounts of leached iron into the solution were much less than allowable amounts of the Iranian wastewater discharge standard, thus no need for secondary treatment. Furthermore, scavengers studies under the optimum conditions showed the dye degradation occurred mainly by surface-bonded hydroxyl radicals. In short, this study proved, Fe3O4/CS/GA NPs are a promising heterogeneous electro-Fenton catalyst due to their low cost, excellent stability and reusability, negligible iron leaching, environmental compatibility, and superior catalytic activity in a wide range of pH.
查看更多>>摘要：Ti metal and its alloys presents excellent mechanical properties and high corrosion resistance. Although Ti element is abundant in nature as oxides compounds, the cost for metal production prevents its larger use. A recent electrochemical process to produce metal from oxides have been developed, the FFC (Fray-Farthing-Chen) process. In this process, electrochemical reactions reduce the metals oxides cathodes through oxygen ionization and further elimination on anode. In this paper, the use of natural rutile sand to produce low-purity Ti metal by the FFC process was studied. X-ray diffraction, scanning electronic microscopy and energy-dispersive X-ray were used to characterize samples subjected to different process conditions. Ti metal was successfully produced, and the reduction pathway was described. Process parameters were studied to optimize the process, and non-pelletized rutile sand was subjected to reduction, improving reaction rate. Mathematical modelling was performed to study kinetic of experiments parameters.
查看更多>>摘要：As biomarkers for pathogenic Listeria monocytogenes, the detection of gene hly, acetoin, and listeriolysin O (LLO) is of great significance for preventing L. monocytogenes infection and diagnosing Listeriosis. Here, a portable paper-based multi-biocatalyst platform was constructed to identify L. monocytogenes by detecting multiple biomarkers at different levels: gene hly (nucleic acid), acetoin (small molecule metabolite), and LLO (protein). The integrating detections of the three biomarkers were successfully performed by two different modified working electrodes on a single paper-based multi-biocatalyst platform. The sensitive and reliable identification of L. monocytogenes was achieved using the portable paper-based multi-biocatalyst platform with wider detection range (from 1.0 x 10(4) to 1.0 x 10(9) CFU mL(-1)) and lower detection limit (10(4) CFU mL(-1)). Additionally, the simpler detection procedure and shorter detection time (2 h) endows the portable platform a better detection performance compared with National Food Safety Standard Method (China-GB 4789.30-2016). Moreover, the results detected by the portable platform in spiked samples were consistent with that obtained by the realtime quantitative polymerase chain reaction method, indicating a good application potential. These unique characteristics suggest that the portable platform provides a reliable identification method for L. monocytogenes.
查看更多>>摘要：Manganese-based oxides are promising as a cost-effective replacement of precious-metal electrocatalysts for oxygen reduction reaction (ORR). Herein, we designed a high-performance Mn3O4 nanoparticles supported on three-dimensional graphene with interconnected hierarchical porous structure by a hydrothermal method, in which coal tar pitch and CaCO3 were used as the carbon precursor and the template, respectively. The as-prepared Mn3O4/3DHG with micropore, mesopore and macropore structure of graphene exhibited more defects and exposed more active sites, which was favorable to improve the electrocatalytic performance. Mn3O4/3DHG showed a higher half-wave potential (0.833 V vs RHE) than 20 wt% Pt/C (0.828 V vs RHE). The accelerated durability tests exhibited half-wave potential of Mn3O4/3DHG shifted by an 18 mV drop after 5000 cycles of cyclic voltammetry scanning, which was smaller than that of 20 wt% Pt/C (8 mV). The electrochemical test results revealed that Mn3O4/3DHG had better catalytic ORR performance than 20 wt% Pt/C.
查看更多>>摘要：In the recent years, fascinating researches in both graphene and MXene systems in various scientific and technological fields have stimulated in exploring MXenes/graphene composites for advanced electrochemical energy storage applications. Their unique mechanical, physicochemical, optical, electrical, and electrochemical properties have encouraged worldwide scientists to take serious motivations in fabricating high-performing supercapacitors for addressing the increasing demands of self-powering, mechanically flexible and wearable electronics befitting not only for daily-used automated gadgets but also in high-tech regimes of biomedical, space research and military sciences. In the present study, the composites' mechanical, electronic charge transport, capacitance properties have been especially recognized and compared to optimize their overall responses for scheming flexible microelectronics. Conclusively, current challenges as well as their future outlooks in addressing the sky-high global energy crisis have also been delineated.
查看更多>>摘要：MoS2, with a high theoretical specific capacity (670 mAh/g), is a good alternative to traditional graphite as anode for lithium ion batteries (LIBs). Poor conductivity and serious volume expansion during charging and discharging process, however, result in poor cycle performance and rate performance of MoS2 anode for LIBs. Here, the TiO2 coated in mesosphere-petal-like shell (MPLS) structure of MoS2 (TiO2@MoS2) and MoS2 encapsulated in hollow mesoporous carbon spheres shell (HMCSS) structure (MoS2@C) are obtained, and effect of different shell structure on lithium storage properties of MoS2 are investigated. The results show that MoS2@C exhibits higher discharge capacity, better rate capability and cycling performance than TiO2@MoS2 and pure MoS2. The significantly enhanced charge and discharge performance of MoS2@C can be attributed to the improvement of electric conductivity and the inhibition of volume expansion result from the introduction of HMCSS structure. Also, TiO2@MoS2 demonstrates remarkable lithium storage performance in comparison with pure MoS2, which is ascribe to MPLS structure of MoS2 assembled from corresponding 2D nanosheets that facilitates the penetration of electrolyte and provides more sites to accommodate Li+, and which is also attribute to TiO2 as effective mechanical support and thus alleviate volume expansion and aggregation of MoS2 during charging and discharging process. It is believed that the different shell structure used in MoS2 provides a novel approach to enhance the lithium storage performance of metal sulfide.
Lee, Min A.Lee, Jeong BeomLee, Je-NamWoo, Sang-Gill...
7页
查看更多>>摘要：A highly fluorinated carbonate molecule-based electrolyte is introduced to enhance the electrochemical performance of lithium metal batteries. The applied bis(2, 2, 2-trifluoroethyl) carbonate (DFDEC) demonstrates impressive performance enhancement by stable oligomeric/LiF-based bi-layered surface modification of Li metal. Li symmetric cell cycling shows prolonged stable electroplating/stripping of Li metal because of the formation of a stable protective bilayer on the Li surface. Furthermore, the negatively shifted HOMO energy level of DFDEC enhances the anodic stability in the high-voltage region on the high-nickel-containing positive electrode surface. Both sophisticated electrochemical characteristics of the DFDEC lead to the enhanced cycle performance of the lithium metal cell.
查看更多>>摘要：A new, feasible, on-line method was proposed to determine Cyclopore polycarbonate membrane thickness by scanning electrochemical impedance microscopy (SEIM) technique. The thickness is 8.4 mu m, which close to the report technical data. Three effective impedances for equivalent circuit model including Cole-Cole diffusion impedance, Cole-Davidson type impedance and O impedance were firstly proposed for radial diffusion and restricted planar diffusion mode when tip electrode on flat or hole surface in Cyclopore membrane. Data analysis results showed that restricted planar diffusion emerged when tip electrode approach tightly to hole surface. Additionally, SEIM responses on the flat and hole surface were compared and could be applied for topographic imaging in the future work.
查看更多>>摘要：A triazole-tethered naphthalimide-ferrocenyl-chalcone (TNFC) derivative was synthesized and investigated for its electrochemical behavior with subsequent successful application as a receptor for the development of differential pulse voltammetric (DPV) and potentiometric sensors for quantification of Cu2+ after receiving confirmatory evidences from UV-Vis, Fluorescence and DFT studies. Cyclic voltammogram of TNFC exhibited two redox peaks at +0.51 V and +0.59 V corresponding to ferrocene/ferrocenium ion redox couple in the potential range of 0 -1.0 V vs Ag/Ag+. On addition of Cu2+, Cyclic voltammogram of TNFC shifted toward more positive potential (anodic shift), indicating the formation of TNFC-Cu2+ complex. DPV sensor demonstrated a selective response towards Cu2+ in the concentration range of 0-26 mu M with detection limit of 0.09 mu M. The TNFC modified carbon paste electrode (CPE) exhibited a selective response for Cu2+ with Nernstian slope of 30.0 mV/decade in the concentration range of 1.0 x 10(-6)-1.0 x 10(-1) M and detection limit 0.79 mu M. High binding constant (3.2 x 10(4) M-1) and negative value of Gibbs free energy (-25.69 kJmol(-1)) calculated using Benesi-Hildebrand (BH) equation confirmed the favorable complexation between TNFC and Cu2+ which was also validated using H-1 NMR and mass spectrometry. The proposed TNFC-CPE was successfully utilized for quantification of Cu2+ content in real samples of water and milk products.
查看更多>>摘要：Rational construction of microstructure and successful incorporation of multiple components offer a scalable strategy for applying electrode materials in asymmetric supercapacitors. Herein, a hierarchical hybrid structure of NiCoAl-layered double hydroxide (NCA-LDH) and ternary spinel NiCo2S4 (NCS) on carbon cloth (CC) without binders is obtained through three-step hydrothermal reaction. The NCA-LDH@NCS@CC electrode exhibits outstanding electrochemical performance with 1775F g(-1) at 1 A g(-1). Its capacitance retention is 79.6% when cycles reach 10 000 under 10 A g(-1), benefiting from the hierarchical hybrid structure and improved overall conductivity. A flexible solid-state asymmetric supercapacitor (FSASC) is assembled using NCALDH@NCS@CC and activated carbon coated on carbon cloth (AC@CC ) for positive and negative electrodes, respectively. It possesses 33.13 Wh kg(-1) under 750 W kg(-1), and also maintains a better cycling performance of 71.4% at 1 A g(-1) after 10 000 cycles. Hierarchical hybrid NCA-LDH@NCS@CC electrode provides a favorable and scalable candidate for the development of FSASC device with superior performance.
NSTL
Elsevier