Ankur YadavPrem Sagar ShuklaJitendra KumarGhanshyam Das Varma...
8页
查看更多>>摘要：Organometal halide perovskites (MHPs) are widely used in energy harvesting as well as energy storage applications due to their superior optoelectronic properties. However, structural, optical, and electronic properties of these materials are strongly dependent on the halide substitution. So far methylammonium lead tri‐bromide‐perovskite‐based supercapacitors have shown an energy density in the range of 10–15?Wh?kg?1. Therefore, further optimization is needed to improve the energy storage efficiency in halide perovskite‐based supercapacitors. It has been observed that the charge storage capacity increases with the increasing ionic conductivity in the perovskite active layer. Herein, a series of porous electrodes are prepared to optimize ionic conductivity by mixing powders of different halide‐based perovskite single crystals for supercapacitor application. It has been demonstrated that maximum efficiency is achieved for a specific bromide composition to iodide ratio with an energy density of ≈22?Wh?kg?1 and a power density of 600?W?kg?1. The ionic conductivity is improved at least by two orders to 3.2?×?10?13?m2?s?1 in the mixed halide sample than pure halide perovskites, while charge transfer resistance is decreased to 40.5?Ω?cm?2. However, overall device stability and Coulombic efficiency decrease with the increasing iodide content.
查看更多>>摘要：Triboelectric nanogenerator (TENG) has the advantages of low cost, low weight, simple structure, and high efficiency. It is a promising low‐frequency mechanical energy capture technology, which shows great potential in dealing with energy and environmental crisis and promoting new electronic products. TENGs have demonstrated irreplaceable design freedom over traditional electronic devices, including its ability to work independently of electrodes. In fact, the displacement current is an unreal current, it can work independently without electrodes. Moreover, due to the lack of “shielding effect” of the electrode, the surface potential can be larger than devices worked with electrodes. Here, based on TENG's high‐voltage characteristic without electrode, the application of dust removal is explored, and a kind of electrodeless polyethylene triboelectric blackboard eraser was demonstrated as an example, which can effectively restrain the flying of chalk dust (limit the dust diffusion within 0.648?m). The electrostatic charge decayed blackboard eraser can be recharged by the electrodeless TENG without requirement of electrodes establishment. In fact, contact electrification may happen frequently in natural environment, and further design may be achieved without the limitation of electrodes.
查看更多>>摘要：Vibration energy harvesting technology aims to convert mechanical energy into electrical energy through piezoelectric effect or electromagnetic induction to supply energy for wireless sensors. Herein, based on polyvinylidene fluoride, a vibration energy harvester who couples piezoelectric effect and electromagnetic induction is proposed, and its performance of energy harvesting is studied from the aspects of multiphysical field, microscale, and energy harvesting circuit. First, a mass‐spring‐damper model is established from the dynamic point of view, and the equivalent circuit models of piezoelectric unit and electromagnetic unit are established from the electrical point of view. Second, the effects of the nonlinear magnetic field, temperature, and microvolume on the resonant frequency and output power density of the energy collector are analyzed by simulation. Finally, a piezoelectric electromagnetic composite energy harvesting circuit is designed and the output voltage rectifying and stabilizing with high electromechanical conversion efficiency is realized. The results show that the harvester realizes the expected functions of inputting alternating current and outputting direct current, with open circuit output voltage up to 6.55?V and output power up to 2.21?mW. This study provides a valuable reference for the research in the field of vibration energy harvesting.
查看更多>>摘要：Next‐generation energy storage systems require green and renewable electrodes with a high specific capacity, which combine biomass waste and bimetallic hydroxide synergically to satisfy environmental enhancements and economic benefits. Herein, a novel approach to improving the electrical conductivity of bimetallic materials by in?situ growing NiCo layered double hydroxides (LDHs) with pseudocapacitance capability on KMnO4‐activated fungus bran‐derived carbons (FBCs) is reported, achieving improved electrochemical performance in supercapacitors (SCs). The hierarchical porous FBC substrate contributes to the homogeneous growth of the LDHs and high electronic and ionic conductivity. The optimal composite (FBC/NCL‐3) with a 3D interconnected structure provides a specific capacitance of 1938?F?g?1 at a current density of 1?A?g?1. Correspondingly, the hybrid battery‐SC device composed of FBC/NCL‐3 and FBC provides favorable stability (76% specific capacity retention at 5?A?g?1 for 3000 cycles) with an operating voltage of 1.4?V and a high energy density of 37.3?Wh?kg?1 at a power density of 695.6?W?kg?1. This work demonstrates a promising strategy using FBC as a substrate for growing LDH materials aiming to achieve high‐performance SCs.
查看更多>>摘要：Monoclinic BiVO4 is extensively exploited in organic oxidation because of its appropriate valence band and remarkable catalytic activity. BiVO4 quantum dots not only have a high specific surface area and active sites for photocatalytic reactions, but can address the short carrier diffusion path problem. Herein, a Z‐scheme BiVO4 quantum dots/reduced graphene oxide/g‐C3N4 photocatalyst is constructed. Benefiting from the distinct BiVO4 quantum dots and layered g‐C3N4 sheets, the photocatalytic compound possesses a considerable light capture capability and surface area. The established Z‐scheme photocatalytic compound with a suitable electronic band structure and redox potential is integrated with a “synthesis and assembly” method. The sodium oleate surfactant plays an important role in the preparation of uniform BiVO4 quantum dots with a diameter of 3–6?nm. The optimized photocatalytic degradation experiments show that the ciprofloxacin and amoxicillin photocatalytic efficiencies are up to 92.2% and 70.7% in 1?h, respectively. It is shown that the improved photocatalytic activities involve in the prolonged lifetime of photogenerated electrons and fast carrier migration in the compound upon simulated sunlight exposure. Herein, a prospective stage for developing more Z‐scheme heterojunctions with excellent photocatalytic properties for antibiotic wastewater treatment and reproducible solar capture in photochemical energy conversion is offered.
查看更多>>摘要：Like titanium metal, nanotube array films can be grown on Ti alloys by anodization in fluoride‐containing electrolytes. Further, the anodization of Ti alloys provide a unique pathway to dope TiO2 nanotubes with the alloying element. However, the details of anodization behaviors of Ti alloys and the obtained nanotubes for application in supercapacitors remain poorly understood. Herein, three Ti–Fe alloys containing different amounts of Fe element (10, 15, and 20?wt%) are fabricated by using a vacuum arc melting furnace. Their anodization behaviors are systematically investigated. The nanotube array films can be achieved on these alloys, which are composed of TiO2, Fe2O3, and Fe‐doped TiO2. Their electrochemical behaviors are completely different from both the pure TiO2 and the pure Fe2O3. The mixed oxide nanotubes on Ti–15?wt%Fe have the maximum capacitance among the three Ti–Fe alloys, which is 3.75 times higher than that of pure TiO2. Moreover, the mixed oxide electrode exhibits high rate capability and excellent cycling stability with only 5.7% loss in capacitance over 10?000 cycles. The presented results suggest that the alloy anodization is an efficient strategy for enhancing the performance of TiO2 electrode materials for supercapacitors.
查看更多>>摘要：Microbial fuel cells (MFCs), unique biosystems that generate energy through exoelectrogens, have undergone significant development in the last decades. Although MFCs have great prospects in environmental protection and power generation, there are still problems of inefficiency and high cost, which are largely attributed to the low performance of anode materials used in MFCs because the anode plays a crucial role in MFCs as a carrier for microbial attachment. In the last few years, researchers have shown great interest in developing advanced anode materials to enhance the performance of MFCs. Herein, an overview of recent progress in the development of anode materials for MFCs is offered. In addition, novel anode modification strategies are summarized. Finally, challenges and development directions of next‐generation anode materials with the potential to finally enable the commercial application of MFCs are discussed.
查看更多>>摘要：As an anode material of lithium‐ion batteries (LIB), Sn has great application potential due to its high theoretical specific capacity. However, the Li–Sn alloying reaction causes serious volume expansion and destroys the electrode structure, resulting in a rapid capacity decay. Herein, a simple preparation method for the Sn–carbon composites (Sn/CF) is designed by electrodepositing Sn nanoparticles on 3D carbon foam (CF) derived from the carbonization of melamine. Sn/CF‐3h exhibits excellent electrochemical properties. At 1?A?g?1, the specific capacity of Sn/CF‐3h remains 166.6?mAh?g?1 with a high capacity retention of 85.4% even over 2000 cycles. The designed structure of the Sn/CF electrode contributes to its excellent performance: providing a 3D conductive network, accommodating volume changes to prevent Sn nanoparticles from losing electrical contact, and promoting contact with electrolyte to accelerate lithium ion transmission.
查看更多>>摘要：Bifunctional electrocatalysts with both accelerated oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) enable high‐power density electricity storage and decentralized extraction of pure oxygen from air for usage in health care. Herein, a hydrothermal synthesis employing the anionic surfactant sodium dodecyl sulfate as structure‐directing agent is developed to fabricate a family of crystalline mesoporous metal oxides (meso‐MO X , M?=?Cr, Fe, Co, Ni, Ce). The pore size and specific surface area depend on the metal used and they range from 3 to 6?nm and 60 to 200?m2?g?1, respectively. NiO and Co3O4 show a higher catalytic efficiency in alkaline media in comparison with the other oxides studied, and their activities are comparable with the values reported for platinum group metal (PGM)‐based electrocatalysts. This stems from lower voltage losses and by the presence of specific hydroxide adsorbates on the surface. Both ORR and OER driven on Co3O4 show the unified rate‐determining chemical step (|OO?|? ads + H2O ? |OOH|? ads + OH?, where | X | ads are the species adsorbed on active sites). The bifunctional ORR/OER electrocatalysis obtained on mesoporous NiO is utilized for the first symmetrical PGM‐free oxygen pump fed by air and water only.
NSTL
Wiley