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With the increasing demand for fruits and vegetables in the market, the development of cold chain logistics has put forward higher requirements for the quality of fruits and vegetables in storage. To ensure the freshness of fruits and vegetables during storage and transportation and avoid unnecessary loss, it is necessary to conduct real-time detection of their odor to ensure their quality. Therefore, based on nano-composite materials combined with Radio Frequency Identification (RFID) technology, this paper designs an integrated RFID sensor that can simultaneously detect temperature, carbon dioxide, and ethanol concentrations. The test results show that the sensor has a high sensitivity of 0.25 dB/°C, 0.011 dB/ppm, and 0.65 MHz/ppm for detecting temperature, carbon dioxide, and ethanol concentration, respectively. The sensor also uses Printed Circuit Board (PCB) technology to make the sensor base, which has the advantages of low cost, easy portability, and mass production capability. The results obtained evidence that the system meets the requirements of environmental monitoring for fruit and vegetable storage, runs stably, and has a high use value. [ABSTRACT FROM AUTHOR]

The hybridization of MXene materials and transition metal dichalcogenides has a significant impact on heterojunction properties. The transport properties and electronic structure of heterojunctions of semiconducting MoS2 and metallic MXene Nb2C were studied by integrating density functional theory with non-equilibrium Green's function theory. The hybridization between Nb2C and MoS2 makes the tunneling barrier between the two layers disappear, which can enhance the electron injection efficiency from the Nb2C to the MoS2. Moreover, the Nb2C/MoS2 heterojunction exhibits a conventional n-type Schottky contact with a barrier height of 0.14 eV, which is significantly lower than the barrier height of 0.29 eV at the Ti/MoS2 junction. These factors result in a field-effect transistor with a low contact resistance of 138 Ω· μ m and a higher current of 1.09 mA μ m−1 at a bias voltage of 0.3 V applied between the left and right electrodes. Following the application of gate voltage, the I on/ I off ratio reaches 1266. [ABSTRACT FROM AUTHOR]

Dual-functional nanomaterial electrodes have the capability to satisfy the requirements for both sweat analysis and the hydrogen evolution reaction (HER), thereby enabling the integration of electrochemical sensing and hydrogen production. In this study, ZIF-67 cubes are synthesized on nickel foam (NF), while TiO2 is obtained through an annealing process. Subsequently, the ZIF-67@TiO2/MoS2 nanocomposite is fabricated on nickel foam via a hydrothermal method. This composite material exhibits exceptional photocatalytic properties and is also suitable for the detection of glucose in sweat. The glucose detection range spans from 10 nM to 10 mM with a sensitivity of 7.24 μA mM−1 cm−2 for a signal-to-noise ratio of 3 and a detection limit of 0.43 μM. Moreover, when utilized as a hydrogen evolution electrode, this material demonstrates a current density of 10 mA cm-2 at an overpotential of 118 mV, with a Tafel slope of 73 mV/dec. The synthesis process is both straightforward and economical. This research introduces a novel concept for the design of multifunctional chemical sensors. [ABSTRACT FROM AUTHOR]

The development of methods for generating pure spin current at the molecular level is vital. In this work, we investigated how the spin-related photocurrent is produced in a cobalt phthalocyanine chain by the photogalvanic effect (PGE). Depending on how the magnetic moments of the left and right halves of the cobalt phthalocyanine chain are arranged, spin current can be generated. Both charge current and spin current are absent when the magnetic moments are arranged in parallel. Pure spin currents are generated when the magnetic moments are arranged in an antiparallel manner. Importantly, the pure spin current is robust to the polarization type and polarization angle. This characteristic results from the structure's charge density having spatial inversion symmetry but lacking that of the spin density. [ABSTRACT FROM AUTHOR]

Constructing and developing nanoarray structures made of non-noble metals that are extremely sensitive to glucose is highly significant. Based on this, this paper used a simple hydrothermal method to orderly grow NiCo2O4 nanowires on flexible carbon cloth to construct ZIF-67@GO nanocubes, a Co-based metal organic framework (Co-MOF) in situ. The preparation of composite materials not only provides a larger surface area and more effective active sites, but also improves charge transport and electrocatalytic performance. Systematically studying the charge transfer process of the composite material and the catalytic oxidation of glucose detection results. Research has revealed that the sensor exhibits excellent electrochemical activity in the process of glucose detection, with a detection linear range of $0.3\mu \text{M}$ - 5.407 mM, a high sensitivity of $990.12~\mu \text{A}$ mM $^{-{1}}$ cm $^{-{2}}$ , low detection limit of $0.16~\mu \text{M}$ (S/ $\text{N}=3$), and a fast response time within 2 s. Additionally, the material has excellent selectivity, reproducibility and stability. Growing NiCo2O4 on CC and constructing a synergistic ZIF-67@GO composite material can overcome the shortcomings of traditional MOF stability and poor conductivity, and its effective electrochemical properties for glucose sensing can provide directions for the determination of biologically active molecules. [ABSTRACT FROM AUTHOR]

In recent years, Radio frequency identification (RFID) technology has been widely used. RFID sensor technology has the advantages of real-time monitoring, accurate data and low cost, and it is applied to mainstream application fields such as asset management, cargo storage, transportation and logistics. A wireless humidity sensor based on zinc oxide (ZnO)/ molybdenum disulfide (MoS2)/ reduced graphene oxide (rGO) is proposed. The structure of the sensor was optimized by HFSS software, and the designed humidity sensor was prepared by heat transfer printing technology. The morphology of ZnO/MoS2/rGO composite was observed by scanning electron microscopy. Nano-rod-like ZnO combined with nano-flower-like MoS2 structure has a large specific surface area and can better adsorb water molecules. This structure well reflects the excellent conductivity of rGO and the sensitivity of MoS2 modified ZnO. The humidity sensor has a resonant frequency of about 178.54 MHz at 10 %-95 % relative humidity (RH) and a sensitivity of 4034 Hz/%RH at high humidity (55 %-95 % RH). In the range of 10 % to 95 % RH, the response time and recovery time of the sensor are 7.4 s and 18.3 s, respectively. The experimental results show that the ZnO/MoS2/rGO composite for humidity sensor is reusable and the sensor is stable in the range of 10%-95% relative humidity. Finally, the sensing mechanism of the sensor under different transmission distances is analyzed. The results show that the sensor is suitable for rapid humidity detection in sealed and open environment. [ABSTRACT FROM AUTHOR]

The development of inexpensive, portable, and high-performance humidity sensors has broad application prospects in disease prevention and health monitoring. In this paper, plant cellulose thin film (PCF) materials such as flute film were used as sensor substrates, and GO/ZnO/PCF nanocomposites were constructed by hydrothermal method, and their resistive humidity sensing performance was studied. The results show that the sensor exhibits good linearity, excellent sensitivity, short response/recovery time, reliable stability, and repeatability over a wide relative humidity range. Furthermore, the rapid response and excellent feasibility of the sensor under different breathing conditions were verified by successfully monitoring normal, rapid, and deep breathing. GO/ZnO/PCF nanocomposites are potential sensing materials for high-performance humidity sensors with promising applications in disease prevention and personal care. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) sensing assisted by metal nanoparticles has attracted much interest due to the fast analysis and low detection limit. Herein, ZnO nanorod (NR) arrays are prepared hydrothermally on the nickel foam (NF) to produce the three-dimensional (3D) ZnO structure for subsequent Au nanoparticle (AuNP) deposition. The AuNPs/ZnO sensor exhibits synergistic catalytic effects in glucose detection. The charge transfer process between AuNPs and the ZnO interface and effects of different light intensities on the catalytic oxidation efficiency in glucose detection are studied systematically. Under UV light irradiation, the sensor exhibits a high sensitivity of 1133.5 µA mM−1 cm−2 which represents a 1.29-fold improvement over that without light (877.9 µA mM−1 cm−2). The sensor shows a large linear range from 1 µM to 6.917 mM as well as a low detection limit of 0.1 µM (S/N = 3). The sensor with excellent selectivity, stability, and reproducibility has large potential in photoelectrochemical nonenzymatic determination of glucose. [ABSTRACT FROM AUTHOR]

Unique nanostructures can provide better electrochemical performance for supercapacitors. The unique network structure is formed by coating MoS2 nanospheres on ZnCo2O4 nanosheets, which has good synergistic effect. In this paper, the MoS2/ZnCo2O4 heterostructures were prepared by two-step hydrothermal method. MoS2/ZnCo2O4 was verified by XRD test, and the microstructure of MoS2/ZnCo2O4 was studied by scanning electron microscopy and transmission electron microscopy. Electrochemical tests show that the heterostructure has a larger specific surface area and more electroactive centers than single ZnCo2O4 or MoS2 nanospheres. Using 1 M KOH as electrolyte, the maximum specific capacitance of the heterostructure nanocomposite electrode is 2705.2 F/g at a current density of 15 A/g. After 2000 cycles at a current density 50 A/g, the initial capacitance remains at 88.2%. A symmetric supercapacitor device with MoS2/ZnCo2O4 as positive and negative electrodes was assembled, which has good electrochemical performance, high capacity of 147 C/g, and good cycling stability of 90.3%. [ABSTRACT FROM AUTHOR]

CoMoO4 microspheres were deposited on nickel (Ni) foam by simple hydrothermal method, and CuCo2O4 nanowires were uniformly grown on CoMoO4 microspheres, then CoMoO4@CuCo2O4 core shell structure composite material was successfully synthesized. The electrochemical test of CoMoO4@CuCo2O4 electrode was completed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge (GCD). These experiment results exhibit that CoMoO4@CuCo2O4 electrode has excellent capacitance characteristic, including a remarkable specific capacitance of 2639 F g−1 at 1 A g−1 and an outstanding cycle life with a captaincy retention of 91.6% after 2000 cycles at 30 A g−1. Furthermore, an asymmetric supercapacitor (ASC) based on CoMoO4@CuCo2O4//activated carbon (AC) exhibited a high energy density of 51.2 W h kg−1 at 800.3 W kg−1. These performances strongly demonstrate that the CoMoO4@CuCo2O4 electrode synthesized by simple methods is an excellent electrode material in the application of supercapacitors (SCs). [ABSTRACT FROM AUTHOR]

Heterostructured Co(OH)2/CuCo2S4/Ni foam electrodes are prepared by using hydrothermal deposition and electrodeposition under optimized conditions and characterized systematically. The nanostructure electrode prepared on the nickel foam provides abundant reaction sites and short diffusion paths for redox reactions and delivers high energy storage performance in supercapacitors due to the suitable mass load and unique morphology. The symmetrical supercapacitor assembled with Co(OH)2/CuCo2S4 shows a high energy density of 52.2 Wh kg−1 at 1236.3 Wh kg−1 and maximum power density of 5530.9 Wh kg−1 at 16.9 Wh kg−1. The excellent properties indicate that Co(OH)2/CuCo2S4 has enormous potential in multifunctional devices such as supercapacitors. [ABSTRACT FROM AUTHOR]

As far as the current situation is concerned, the energy storage of supercapacitors is still a problem that is widely concerned and urgently needed to be solved in the industry. In this paper, we successfully prepared a multi-dimensional zinc-cobalt-molybdenum hybrid metal oxide nanocomposite as a high energy density supercapacitor device on nickel foam by hydrothermal method. Below, we will abbreviate the zinc-cobalt-molybdenum hybrid metal oxide as Zn-Co-Mo. The morphology and electrochemical properties of Zn-Co-Mo/Ni composites were systematically studied. Compared with ZnCo2O4/Ni or CoMoO4/Ni composites, it showed higher electrochemical energy storage performance. For example, when the current density is 60 mA cm−2, the Zn-Co-Mo electrode shows a high specific capacitance of 384 F/g. After 5000 cycles, the capacitance of the Zn-Co-Mo composite was kept at 81.25%, which indicates that the Zn-Co-Mo composite electrode is feasible as an electrode material in the field of supercapacitors. [ABSTRACT FROM AUTHOR]

Electrode materials with high conductivity and excellent redox characteristics are vital to supercapacitors in electrochemical energy storage. Herein, a graphene/Co3O4/Co(OH)2/Ni electrode synthesized hydrothermally has high specific capacitance and the morphology and structure of the graphene/Co3O4/Co(OH)2/Ni electrodes are characterized systematically. The three electrode charge–discharge test exhibits an excellent specific capacitance of 3216 F g−1 at 5 A g−1. The two electrode charge–discharge capacitance decreases from an initial value of 195 to 140 F g−1 after 5000 cycles showing capacitance retention of 71.1%. A test device is fabricated with (OH)2/Co3O4/graphene/Ni as the positive electrode and carbon/nickel foam as the negative electrode. After charging for 15 s, two such devices in series can efficiently power five 5-mm-diameter light-emitting diodes (LEDs) and the excellent electrochemical performance reveals large potential in next-generation high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Porous graphene/Si-MCP (microchannel plate) microstructures are fabricated using electrochemical exfoliation and microelectronic machining. The few-layer graphene nanosheets with a lateral size of 600-850 nm and thickness of 2-3 nm are uniformed anchored on the surface and channels of the Si-MCP substrate. The as-prepared graphene/Si-MCP is used as the anode in lithium ion batteries and demonstrated to have a higher reversible capacity, better cycling retention, and excellent higher rate cycling performance compared to graphene/Si and Si-MCP. The good properties are attributed to the large surface-to-volume ratio of the structure and the better electrical contact with graphene. This silicon-based composite has large potential as anodes in integrated batteries. [ABSTRACT FROM AUTHOR]

The detection of glucose has been attracting more and more attention. The present work provided a novel glucose sensor based on graphene/zinc oxide nanoparticle nanocomposite modified Ni foam to fabricate an electrode (G-ZnO/Ni foam). The structure and morphology of the electrode were characterized by SEM, XPS, and XRD. And the electrochemical performance of G-ZnO/Ni foam electrode was evaluated using cyclic voltammetry (CV) and amperometry analysis. The resulting electrode exhibited excellent electrocatalytic activity toward the reduction of glucose in a linear range of 50-1000 μmol with a correlation coefficient of 0.986. The sensitivity of the graphene/zinc oxide nanocomposite modified Ni foam sensor was 1635.52 μA mM−1 cm−2. It is has better electrochemical performance for glucose and is promising in high-sensitivity detection of glucose applications. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional graphene wrapped silicon nanowire (SiNWs) architecture was synthesized by electrochemical exfoliation method and proposed to be the counter electrode for dye-sensitized solar cells (DSSCs). The results show that the few high-quality layers of graphene sheets have been obtained by electrochemical exfoliation method. The size of graphene is distributed from 550nm to 650nm, appropriately dispersed onto the SiNW supporter. The graphene/SiNW nanostructure still vertically aligned to the substrate finely. The channel between each wire is clear. The fabricated graphene/SiNWs electrode is a promising structure for future applications. The performance of the graphene/SiNWs as the counter electrode is found to be dependent on its dispersion in the whole backbone, with better dispersion offering more surface areas for the catalytic reduction reaction. Electrochemical tests reveal that the DSSC with graphene/SiNWs exhibits higher electro-catalytic activity and lower charge transfer resistance, suggesting that the 3D structure presents a potential way to fabricate low-cost, integrated and metal-free counter electrode for high-performance DSSCs. The DSSC based on graphene/ SiNWs has an open-circuit voltage () of 738.11mV, short-circuit current density () of 15.48mA cm, fill factor (FF) of 0.67 and conversion efficiency () of 7.66%. With the increase of graphene content, the SiNWs will support more graphene nanosheet per areas. When the graphene content exceeds a certain value, the graphene will not uniformly disperse. So, graphene aggregated seriously, which may influence the photovoltaic performance. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) graphene/NiO/Si-microchannel (MCP) composite electrode is synthesized by the conventional microelectronic machining process and electrochemical exfoliation technology for electrochemical capacitors. SEM, AFM, and Raman scattering are used to investigate the morphology and structure, and electrochemical characterization reveals that the 3D graphene/NiO/Si-MCP has a high specific capacitance of 833 Fg at a current density of 5 Ag in 6 mol L KOH. Moreover, good cycling performance with 92% capacitance retention after 1000 cycles is observed indicating the novel electrode has large potential in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

A Pd-Ni nanoparticle modified silicon-based anode is fabricated and the possibility of using it for the direct alkaline fuel cell of carbohydrates has been investigated by electrochemical method. Upright and porous ordered silicon nanowires (SiNWs) arrays are prepared by wet etching. The Pd-Ni nanoparticles are covered to the SiNWs uniformly by chemical deposited successively. Using six kinds of common carbohydrate, including glucose, fructose, maltose, lactose, sucrose, and starch, as testing subjects, the performance of electrocatalytic oxidation is studied. Experiment results show that the electrochemically active surface area of Pd-Ni/SiNWs electrode electrochemically active surface area is 53.482 cm, and higher electrocatalytic activity and stability is displayed for the direct oxidation of glucose, fructose, maltose, and lactose. Firstly, the Pd-Ni/SiNWs electrode has better electrochemical performance for carbohydrates and is promising for applications in direct alkaline fuel. Secondly, more kinds of carbohydrates might potentially use as energy source for direct alkaline fuel. [ABSTRACT FROM AUTHOR]

Almost vertically aligned ZnO nanowires have been grown on Silicon substrates via a simple hydrothermal method. In order to improve the photoelectric conversion efficiency for fabricated dye-sensitized solar cells (DSSCs), an easily-operated immersing method was employed to fabricate a TiO/ZnO nanowires array heterojunction, which has advantage of high aspect ratio, low recombination rate and high absorption of visible light. The structure and surface morphology of the samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The photovoltaic properties of TiO/ZnO based DSCCs were measured by considering the power efficiency (η), photocurrent density ( J ), open-circuit voltage ( V ), and fill factor (FF). An efficiency of 0.559% is achieved for the composite cell, increasing 0.426 and 0.185% for the ZnO nanowires cell and TiO cell, respectively. The short-circuit current and open-circuit voltage are also enhancing. The improvements are because of high surface are of TiO shell layer, as well as fast electron transport and light scattering effect of ZnO nanowires. [ABSTRACT FROM AUTHOR]

Silicon microchannel plates (MCP) modified by nickel-palladium nanoparticles (Ni-Pd/Si-MCP) have highly ordered microchannels with uniform diameters and lengths isolated and parallel to one another and are excellent sensors for the determination of methanol in alkaline solutions. The 3D ordered Si MCP is fabricated by electrochemical etching used as the backbone, and the Ni-Pd nanoparticles are sensitive materials for detecting methanol that was obtained by an electroless plating method. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods were employed to characterize the Ni-Pd/Si-MCP structure. An electrochemical workstation was used to monitor the sensing characteristics of the Ni-Pd/Si-MCP electrode. As a result of the synergetic effects rendered by the MCP and Ni-Pd nanoparticles, these sensors present a high sensitivity of 0.168 mA mM−1, and the detection limits was 12 μM. In particular, since the fabrication process is compatible with conventional silicon technology, the structure has immense potential as an efficient, nonenzymatic, and integrated methanol sensors. [ABSTRACT FROM AUTHOR]