Intricate Ionic Behaviors in High-Performance Self-Powered Hydrothermal Chemical Generator Using Water and Iron (III) Gate.

Utilizing the ionic flux to generate voltage output has been confirmed as an effective way to meet the requirements of clean energy sources. Different from ionic thermoelectric (i-TE) and hydrovoltaic devices, a new hydrothermal chemical generator is designed by amorphous FeCl3 particles dispersing in MWCNT and unique ferric chloride or water gate. In the presence of gate, the special ion behaviors enable the cell to present a constant voltage of 0.60 V lasting for over 96 h without temperature difference. Combining the differences of cation concentration, humidity and temperature between the right and left side of sample, the maximum short-circuit current and power output can be obtained to 168.46 µA and 28.11 µW, respectively. The generator also can utilize the low-grade heat to produce electricity wherein Seebeck coefficient is 6.79 mV K-1 . The emerged hydrothermal chemical generator offers a novel approach to utilize the low-grade heat, water and salt solution resources, which provides a simple, sustainable and low-cost strategy to realize energy supply.

Atmospheric electrostatic induction on carrier transfer in volumetric photoelectrochemical system with MXene-modified electrodes.

With WO3/BiVO4/MXene ternary composite layers as a working electrode, a smart volumetric photoelectrochemical system using electrostatic bias voltage inducted by atmospheric electric field was developed. Under single sun illumination and 0.8 V hardwired bias, the current response of the ternary electrode is 1.15 mA cm-2, which is 1.31 times higher than that of the WO3/BiVO4 electrode, mainly due to the higher charge transfer rate between the MXene layer and the BiVO4 structure. Further, the response of the ternary electrode increases to 1.39 mA cm-2 at an extra atmospheric electric field of 1100 V m-1. It can be demonstrated that the effect of the atmospheric electric field can be regarded as an extra hardwired bias of 0.101 V in the system. The experimental results reveal that the native carriers, including inducted electron/holes in MXene and BiVO4, and carriers in the electrolyte, are all effectively excited by the electrostatic induction of atmospheric electric field.

Highly Transparent and Flexible Zn-Ti3C2Tx MXene Hybrid Capacitors.

With the development of transparent and wearable electronic devices, energy supply units with high transmittance and flexibility, long cycle life, and high power and energy density are urgently needed. Zinc ion hybrid capacitors (ZIHCs) combined with the advantages of both supercapacitors and zinc ion batteries are promising energy supply components in the abovementioned devices. In addition, the preparation of multifunctional devices has become a trend for the need of space- and resource-saving. Therefore, obtaining ZIHCs with high transmittance and exploring their potential applications are meaningful challenges. Herein, a transparent and flexible ZIHC composed of a patterned zinc foil anode, transparent MXene cathode, and ZnSO4-polyacrylamide (PAM) hydrogel electrolyte is designed and realized. The ZIHC exhibits a superior capacitance of 318 µF cm-2 (5 mV s-1) with 94% transmittance and retains 76% of the initial capacitance after 10,000 charge-discharge cycles. It also shows excellent flexibility, i.e., its capacitance has no obvious attenuation under different bending states. Interestingly, the leakage current of the ZIHC is highly sensitive to electric fields, which shows potential application in electric field detection. This work presents a method to realize the multifunctional ZIHC with electric field sensing function for transparent and flexible wearable devices in the future.

A Self-Powered Flexible Thermoelectric Sensor and Its Application on the Basis of the Hollow PEDOT:PSS Fiber.

The thermoelectric (TE) fiber, based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which possesses good flexibility, a low cost, good environmental stability and non-toxicity, has attracted more attention due to its promising applications in energy harvesting. This study presents a self-powered flexible sensor based on the TE properties of the hollow PEDOT:PSS fiber. The hollow structure of the fiber was synthesized using traditional wet spinning. The sensor was applied to an application for finger touch, and showed both long-term stability and good reliability towards external force. The sensor had a high scalability and was simple to develop. When figures touched the sensors, a temperature difference of 6 °C was formed between the figure and the outside environment. The summit output voltages of the sensors with 1 to 5 legs gradually increased from 90.8 µV to 404 µV. The time needed for the output voltage to reach 90% of its peak value is only 2.7 s. Five sensors of legs ranging from 1 to 5 were used to assemble the selector. This study may provide a new proposal to produce a self-powered, long-term and stable skin sensor, which is suitable for wearable devices in personal electronic fields.

A New Free-Standing Aqueous Zinc-Ion Capacitor Based on MnO2-CNTs Cathode and MXene Anode.

Restricted by their energy storage mechanism, current energy storage devices have certain drawbacks, such as low power density for batteries and low energy density for supercapacitors. Fortunately, the nearest ion capacitors, such as lithium-ion and sodium-ion capacitors containing battery-type and capacitor-type electrodes, may allow achieving both high energy and power densities. For the inspiration, a new zinc-ion capacitor (ZIC) has been designed and realized by assembling the free-standing manganese dioxide-carbon nanotubes (MnO2-CNTs) battery-type cathode and MXene (Ti3C2Tx) capacitor-type anode in an aqueous electrolyte. The ZIC can avoid the insecurity issues that frequently occurred in lithium-ion and sodium-ion capacitors in organic electrolytes. As expected, the ZIC in an aqueous liquid electrolyte exhibits excellent electrochemical performance (based on the total weight of cathode and anode), such as a high specific capacitance of 115.1 F g-1 (1 mV s-1), high energy density of 98.6 Wh kg-1 (77.5 W kg-1), high power density of 2480.6 W kg-1 (29.7 Wh kg-1), and high capacitance retention of ~ 83.6% of its initial capacitance (15,000 cycles). Even in an aqueous gel electrolyte, the ZIC also exhibits excellent performance. This work provides an essential strategy for designing next-generation high-performance energy storage devices.

Analysis of influencing factors on soil Zn content using generalized additive model.

Soil zinc (Zn) plays a crucial role in plant growth, but excessive accumulation in the environment may lead to air, water and soil pollution. It is affected by various chemical, environmental and spatial factors. Therefore, it is important to identify the factors influencing Zn content in the landscape. The main motivation for this study is to determine the suitability of a generalized additive model (GAM) to describe change in soil Zn content due to influencing factors. A total of 1497 soil nutrient samples were collected in Fangshan District, Beijing, China. Organic matter (OM), available phosphorus (AP), available potassium (AK), alkali-hydrolyzed nitrogen (AHN) and slowly available potassium (SAK) are considered. The relationship between Zn, nutrients and geographic location (latitude & longitude) is investigated using the GAM. More precisely, the Akaike information criterion (AIC) is used to select influencing factors on Zn content and cross-validated to avoid overfitting of the multivariate model. The results show that Zn content reaches its maximum at latitude 39.8°N and longitude 115.9°E. Zinc content increases as AP increases to 150 mg/kg. When OM content is greater than 90 g/kg, Zinc content decreases with an increase in OM content. Factors that affected Zn content, in descending order of significance derived from deviance explained and adjustment coefficient of determination (Adj.R2) were AP, latitude, AHN, AK and OM. Moreover, the interactions between latitude and longitude, AHN and AP, OM and AK have significant impact on Zn.

Compressible Supercapacitor with Residual Stress Effect for Sensitive Elastic-Electrochemical Stress Sensor.

In this work, we have synthesized graphene aerogels using natural-drying method and fabricated a compressible all-solid-state supercapacitor, which offers outstanding energy density of 23.08 Wh kg-1 at 240 W kg-1. We further demonstrate that the device is deformable in squeezed cases with a residual stress effect. Taking advantage of the compressibility and excellent electrochemical performance of the graphene aerogel, we offer a new type of stress sensor called elastic-electrochemical stress sensor. Served as the elastic-electrochemical stress device, the cell demonstrates steady response current toward the external mechanical force by transforming mechanical energy to electrochemical energy. The high-sensitive stress sensor will help us comprehend the interaction principle between electrochemistry and external stress well.

The effect of pre-competition training on biochemical indices and immune function of volleyball players.

OBJECTIVE: Pre-competition sports training can have varying effects on an athlete's immune function, including causing reduced resistance. The aim of this study was to explore effects of pre-competition training on some biochemical indices and immunologic functions in top-level volleyball athletes to determine whether training should be modified for optimal health. METHODS: Biochemical indices (Hb, BUN, CK, LDH) and immunologic function (IgA, IgG, IgM, CD3(+), CD4(+), CD8(+)) were detected by semiautomatic biochemistry analyzer, light scattering photometer, or flow cytometry in sera from 24 top-level volleyball athletes and compared before and after pre-competition training. RESULTS: After training, the levels of Hb, IgA, IgG, IgM, and CD4(+) and the CD4(+)/CD8(+) ratio decreased significantly, while BUN, CK, LDH, and CD8(+) increased significantly (P < 0.05). Further, the decrease in Hb levels in female athletes was more significant than that in male athletes (P < 0.05). CONCLUSIONS: These results indicate that pre-competition training affects biochemical indices and immunologic function in this group of athletes. Additionally, more dramatic changes in Hb in female athletes may indicate a need for adapted training loads and rest periods for females.