The layered sodium transition metal oxide, NaTMO2 (TM = transition metal), with a binary or ternary phases has displayed outstanding electrochemical performance as a new class of strategy cathode ...materials for sodium‐ion batteries (SIBs). Herein, an in‐depth phase analysis of developed Na1−xTMO2 cathode materials, Na0.76Ni0.20Fe0.40Mn0.40O2 with P2‐ and O3‐type phases (NFMO‐P2/O3) is offered. Structural visualization on an atomic scale is also provided and the following findings are unveiled: i) the existence of a mixed‐phase intergrowth layer distribution and unequal distribution of P2 and O3 phases along two different crystal plane indices and ii) a complete reversible charge/discharge process for the initial two cycles that displays a simple phase transformation, which is unprecedented. Moreover, first‐principles calculations support the evidence of the formation of a binary NFMO‐P2/O3 compound, over the proposed hypothetical monophasic structures (O3, P3, O′3, and P2 phases). As a result, the synergetic effect of the simultaneous existence of P‐ and O‐type phases with their unique structures allows an extraordinary level of capacity retention in a wide range of voltage (1.5–4.5 V). It is believed that the insightful understanding of the proposed materials can introduce new perspectives for the development of high‐voltage cathode materials for SIBs.
In‐depth phase analysis of developed Na1−xTMO2 cathode materials, NFMO with P2‐ and O3‐type phases (NFMO‐P2/O3) is offered. As a result, the synergetic effect of the simultaneous existence of P‐ and O‐type phases with their unique structures allows an extraordinary level of capacity retention in a wide range of voltage (1.5–4.5 V).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The importance of hydrogen peroxide (H2O2) continues to grow globally. Deriving the oxygen reduction reaction (ORR) toward the 2e– pathway to form H2O2 is crucial for high H2O2 productivity. However, ...most selective electrocatalysts following the 2e– pathway comprise carbon‐containing organic materials with intrinsically low stability, thereby limiting their commercial applicability. Herein, layered double hydroxides (LDHs) are used as inorganic matrices for the first time. The LDH catalyst developed herein exhibits near‐100% 2e– ORR selectivity and stably produces H2O2 with a concentration of ≈108.2 mm cm–2photoanode in 24 h in a two‐compartment system (with a photoanode) with a solar‐to‐chemical conversion efficiency of ≈3.24%, the highest among all reported systems. Density functional theory calculations show that 2e– ORR selectivity is promoted by atomically dispersed cobalt atoms in (012) planes of the LDH catalyst, while a free energy gap between the *O and OOH– states is an important factor.
A highly 2e– oxygen reduction pathway‐selective layered double hydroxide (LDH) catalyst is proposed to increase the yield of H2O2 production. A two‐compartment photoelectrochemical system with the catalyst can catalyze H2O2 generation with concentrations of ≈108.2 mm cm–2 in 24 h without any external bias. A solar‐to‐chemical conversion efficiency of ≈3.24% is recorded, which is the highest efficiency among those of all reported systems.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Summary
A data acquisition system for precision agriculture is presented. The system can collects various time‐series data on target plants and their environmental facts. The designed system consists ...of a server and multiple intra‐networked stations and includes a software toolkit that has two independent but synchronized data acquisition processes. The one is for measurements on environmental facts around a target plant and the other is for volume estimation of the target plant adopting multi‐view stereo techniques. An analysis on sampling rate and data acquisition experiments for testing purposes were performed. A data filtering method based on the fast Fourier transform is applied to analyze the noise immunity of the collected data. For the volume estimation, three different methods, ie, method‐I using 2‐D projection on slices, method‐II using polyhedrons on voxels, and method‐III using enclosed surfaces, were devised to handle various plant types and examined for three different type of target plants. The volume estimation errors were measured in range of 6 ∼ 30% in the experiments.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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•First time we report the synthesis of CuCo2O4 nanobelts using hydrothermal method.•The spinel CuCo2O4 nanobelts exhibit maximum areal capacitance of 2.42Fcm−2.•After 1800 cycles, ...127% of the initial specific capacitance was retained.
One dimensional hierarchical CuCo2O4 nanobelt like architecture was synthesized via hydrothermal method. The synthesized nanomaterial was characterized using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The TEM image clearly shows the nanobelt like architecture of CuCo2O4. The supercapacitor properties of CuCo2O4 nanobelts electrode were tested using cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy. The spinel CuCo2O4 nanobelts exhibit maximum areal and specific capacitance of 2.42Fcm−2 (809Fg−1). After 1800 continuous charge-discharge cycles, 127% of the initial capacitance was retained. This superior electrochemical supercapacitor property is mainly due to increased surface area and ion transport of nanobelt like architecture. The charge transfer resistance (Rct) value of CuCo2O4 nanobelt electrode is 3.85Ω. This high capacitance and cyclic stability demonstrate that the prepared CuCo2O4 nanobelts are a promising candidate for supercapacitors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
It is important to improve the overall efficiency of a photovoltaic (PV) inverter when it is connected to the grid. Fundamentally, the conversion efficiency from dc to ac power of an inverter is ...important. However, in the presence of partial shading, maximum power point tracking (MPPT) on PV modules is more important than the conversion efficiency. In this paper, a new control method for a three-level inverter is proposed. With the proposed method, each dc-link voltage of the three-level inverter can be asymmetrically regulated. When PV modules are split into two and each split module is connected to the respective dc-link capacitors of the inverter, the asymmetric control can be helpful because separate MPPTs are possible. The effectiveness of the proposed method was examined through experiments with a T-type three-level inverter, where each dc-link capacitor was supplied by a PV simulator emulating two separate PV modules under different shading conditions.
Lithium vanadyl phosphate has seven different crystallographic phases. Among them, α‐LiVOPO4 is chosen because of its relatively high energy density and redox voltage of 3.9 V compared to the other ...phosphates. In this study, Ti4+‐doped α‐LiV1−xTixOPO4 (x = 0.00, 0.003, 0.005, 0.007, and 0.01) was prepared using a sol–gel method to increase the structure stability and electrochemical performance. The triclinic structure with the space group P‐1 was confirmed by X‐ray diffraction, Fourier‐transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. Inductively coupled plasma–optical emission spectroscopy was conducted to determine the precise state. The shape and size of the particles were observed by field‐emission scanning electron microscopy. In situ X‐ray absorption spectroscopy was performed to confirm the structural behavior during the electrochemical reaction. Electrochemical measurements such as cyclic voltammetry and galvanostatic charge–discharge were conducted. α‐LiV1−xTi
xOPO4 (x = 0.003, 0.005, 0.007, and 0.01) showed structural stability during cycling as well as decreased polarization during charge and discharge with the increased diffusion coefficient of lithium ions. α‐LiV0.995Ti0.005OPO4 showed the best cycling stability and rate capability among all the samples examined because Ti doping retained its site to prevent structural collapse.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
To avoid fraudulent practices, LC-Orbitrap and FT-NIRS combined with multivariate analysis was used to distinguish between 53 Korean and foreign Boston butt samples; forty were used to establish the ...calibration model and 13 were used as an external validation set. Twenty metabolites were determined to be good indicators of geographic origin. Both LC-Orbitrap with CDA model based on 20 metabolites and FT-NIRS with PLS achieved 100% efficiency in identifying Korean and foreign samples; overall predictive rates for LC-Orbitrap (94.9%) and FT-NIRS (100%). Thus, combined use of LC-Orbitrap and FT-NIRS could be proposed to determine reliably discriminate geographic origins of pork samples.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
We report a three-dimensional (3D) molecular orientation control of a liquid crystal organic semiconductor (LC-OSC) based on the long-range ordering characteristic of an LC material. To this ...end, a synthetic LC-OSC molecule, MeOPh-BTBT-C8, with a fluidic nematic (N) phase that is essential for alignment control over a large area and a smectic E (SmE) phase showing high ordering, was prepared. A simple flipping of a sandwich cell made of the LC-OSC material between the top and bottom substrates that have uniaxial–planar degenerated alignment as well as crossed rubbing directions responds to the given surface anchoring condition and temperature gradient. Optical observation of the alignment-controlled LC-OSC was carried out by polarized optical microscopy (POM), and the corresponding charge carrier mobility was also measured by fabricating organic field-effect transistors (OFETs). Our platform offers a facile approach for multidirectional and multifunctional organic electronic devices using the stimulus–response characteristics of LC materials.
Thin layered nanosheets of ZnCo2O4 with desirable porous nanoarchitecture grown on Ni-foam were prepared using a simple surfactant free hydrothermal method. The Ni-foam supported ZnCo2O4 ...nanostructure was characterized using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). FESEM clearly revealed thin nanosheets which were randomly connected together to form a porous structure. The binder-free Ni-foam supported ZnCo2O4 electrode was applied directly to hybrid supercapacitor analysis. In three electrode measurement, thin layered nanosheets of ZnCo2O4 exhibited a maximum specific capacity of 886 C g−1 at a current density of 2 mA cm−2. When the current density was increased from 2 to 50 mA cm−2, the specific capacity value was 362.5 C g−1. After 2000 continuous charge–discharge cycles, about 94% of the maximum specific capacity was retained. This high specific capacity, better rate capacity, and excellent cyclic stability of thin layered nanosheets of ZnCo2O4 suggest that the prepared electrode is a promising candidate for hybrid supercapacitor applications.
Binder-free, Ni-foam supported thin layered nanosheets of ZnCo2O4 were successfully fabricated via a surfactant-free hydrothermal method. This desirable thin layered nanosheets of ZnCo2O4 nanoarchitecture grown on Ni-foam exhibited the high specific capacity of 886 C g−1 at 2 mA cm−2 with excellent cyclic stability (103%) for 2000 charge–discharge cycles. Display omitted
•This paper reports the hydrothermal preparation of ZnCo2O4 on Ni-foam.•The ZnCo2O4 nanosheet exhibits maximum specific capacity of 886 C g−1.•After 2000 cycles, 103% of the initial specific capacity was retained.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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