Polyoxometalate-based electrolyte materials in redox flow batteries:Current trends and emerging opportunities

Redox flow batteries have received wide attention for electrochemical energy conversion and storage devices due to their specific advantage of uncoupled power and energy devices,and therefore potentially to reduce the capital costs of energy storage.Terrific structural features of polyoxometalates exhibit unique advantages in redox flow batteries,such as,stable chemical properties,multi-electron reaction,good redox reversibility,low permeability,etc,which furnishes a novel perspective for settling various problems of redox flow batteries.This was a comprehensive and critical review of this type of batteries,focusing mainly on the chemistry of polyoxometalate electrolyte materials and introducing a systematic classification.Finally,challenges and perspectives of polyoxometalate electrolyte materials and polyoxometalate redox flow batteries are discussed.

High-entropy L1_(2)-Pt(FeCoNiCuZn)_(3) intermetallics for ultrastable oxygen reduction reaction

Enhancing the stability of Pt-based electrocatalysts for the sluggish cathodic oxygen reduction reaction(ORR)is critical for proton exchange membrane fuel cells(PEMFCs).Herein,high-entropy intermetallic(HEI)L1_(2)-Pt(FeCoNiCuZn)3is designed for durable ORR catalysis.Benefiting from the unique HEI structure and the enhanced intermetallic phase stability,Pt(FeCoNiCuZn)3/C nanoparticles demonstrate significantly improved stability over Pt/C and PtCu_(3)/C catalysts.The Pt(FeCoNiCuZn)3/C exhibits a negligible decay of the half-wave potential during 30,000 potential cycles from 0.6 to 1.0 V,whereas Pt/C and PtCu_(3)/C are negatively shifted by 46 and 36 m V,respectively.Even after 10,000 cycles at potential up to 1.5 V,the mass activity of Pt(FeCoNiCuZn)3/C still shows~70%retention.As evidenced by the structural characterizations,the HEI structure of Pt(FeCoNiCuZn)3/C is well maintained,while PtCu_(3)/C nanoparticles undergo severe Cu leaching and particle growth.In addition,when assembled Pt(FeCoNiCuZn)3/C as the cathode in high-temperature PEMFC of 160℃,the H_(2)-O_(2)fuel cell delivers almost no degradation even after operating for 150 h,demonstrating the potential for fuel cell applications.This work provides a facile design strategy for the development of high-performance ultrastable electrocatalysts.

Tuning Metallic Co0.85Se Quantum Dots/Carbon Hollow Polyhedrons with Tertiary Hierarchical Structure for High-Performance Potassium Ion Batteries

Potassium-ion batteries(KIBs)are a potential candidate to lithium-ion batteries(LIBs)but possess unsatisfactory capacity and rate properties.Herein,the metallic cobalt selenide quantum dots(Co0.85Se-QDs)encapsulated in mesoporous carbon matrix were designed via a direct hydrothermal method.Specifically,the cobalt selenide/carbon composite(Co0.85Se-QDs/C)possesses tertiary hierarchical structure,which is the primary quantum dots,the secondary petals flake,and the tertiary hollow micropolyhedron framework.Co0.85Se-QDs are homogenously embedded into the carbon petals flake,which constitute the hollow polyhedral framework.This unique structure can take the advantages of both nanoscale and microscale features:Co0.85Se-QDs can expand in a multidimensional and ductile carbon matrix and reduce the K-intercalation stress in particle dimensions;the micropetals can restrain the agglomeration of active materials and promote the transportation of potassium ion and electron.In addition,the hollow carbon framework buffers volume expansion,maintains the structural integrity,and increases the electronic conductivity.Benefiting from this tertiary hierarchical structure,outstanding K-storage performance(402 mAh g?1 after 100 cycles at 50 mA g?1)is obtained when Co0.85Se-QDs/C is used as KIBs anode.More importantly,the selenization process in this work is newly reported and can be generally extended to prepare other quantum dots encapsulated in edge-limited frameworks for excellent energy storage.

Diamond-structured hollow-tube lattice Ni materials via 3D printing

Light-weight and high-strength materials have attracted considerable attention owing to their outstanding properties, such as weight-reducing, acoustic absorption, thermal insulation, shock and vibration damping. Diamond possesses specific stiffness and strength arising from its special crystal structure. In this work, inspired by the diamond crystal structure, hollow-tube nickel materials with the diamond structure were fabricated using a diamond structured polymer template based on the Stereo Lithography Appearance technology. The diamond structured template was coated with Ni-P by electroless plating. Finally, the template was removed by high temperature calcinations. The density of the hollow tube nickel materials is about 20 mg/cm3. The morphology and composition of the resultant materials were characterized by scanning electron microscope, energy-dispersive spectrometry, and X-ray diffraction. The results showed that the surface of the Ni film was uniform with the thickness of 4 μm.The mechanical property was also measured by stress and strain tester. The maximum compression stress can be reached to40.6 KPa.

Bio-inspired multifunctional metallic glass

As a novel class of metallic materials, bulk metallic glasses(BMGs) have attracted a great deal of attention owing to their technological promise for practical engineering applications. In nature, biological materials exhibit inherent multifunctional integration, which provides some inspiration for scientists and engineers to construct multifunctional artificial materials. In this contribution, inspired by superhydrophobic self-cleaning lotus leaves, multifunctional bulk metallic glasses(BMG) materials have been fabricated through the thermoplastic forming-based process followed by the SiO_2/soot deposition. To mimic the microscale papillae of the lotus leaf, the BMG micropillar with a hemispherical top was first fabricated using micro-patterned silicon templates based on thermoplastic forming. The deposited randomly distributed SiO_2/soot nanostructures covered on BMG micropillars are similar to the branch-like nanostructures on papillae of the lotus leaf. Micro-nanoscale hierarchical structures endow BMG replica with superhydrophobicity, a low adhesion towards water, and self-cleaning, similar to the natural lotus leaf. Furthermore, on the basis of the observation of the morphology of BMG replica in the Si mould, the formation mechanism of BMG replica was proposed in this work. The BMG materials with multifunction integration would extend their practical engineering applications and we expect this method could be widely adopted for the fabrication of other multifunctional BMG surfaces.

A Direct Liquid Fuel Cell with High Power Density Using Reduced Phosphotungstic Acid as Redox Fuel

Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).

Improvement in potassium ion batteries electrodes: Recent developments and efficient approaches

Demand for efficient and continuous application for high-grid energy storage systems involves the study towards novel battery technologies. Hence, considering the vast naturally available resources of potassium all over the world and its encouraging intercalation chemistries, it has recently enticed attention in electrochemical energy storage industry in the form of potassium ion batteries (PIBs). The major factor in this K+ based battery, is to develop efficient approaches to manufacture electrode substance to intercalate its big size potassium ions with considerable voltage, kinetics, charge/discharge capacity, capacity retention, cost, etc. This study contributes in the recent developments of anode and cathode materials for PIBs, including several electrode materials in regards to synthesis, structure, electrochemical performance, and K-storage mechanisms. Finally, the review contributes to provide helpful sources for the increasing number of scientists working in this industry regarding its critical issues and challenges and also to indicate the future direction of electrode materials in PIBs.

桃皮效应:准超疏水高黏附表面(英文)

桃皮表面具有特殊的浸润和黏附性质.本文揭示了桃皮表面主要由长、短2种绒毛组成.其中长绒毛含有较多疏水的蜡质,短绒毛含有较多亲水的多糖基团.正是由于2种绒毛的化学组成和微观结构使得桃皮表面具有准-超疏水、高黏附的性质.桃皮表面的水滴能够维持良好的球形,即使将桃皮倒立放置,水滴也不会滚动,我们将此定义为桃皮效应.通过化学法和物理法改变其表面化学组成和微观形貌,推断出水滴在桃皮表面以Wenzel和Cassie共存态存在,使得水滴与桃皮表面产生较强的相互作用,从而使桃皮表面具有超疏水和高黏附性质.

Chinese brushes： From controllable liquid manipulation to template-free printing microlines

作为为书法和画的一台传统的作品仪器，中国刷子由于它 controllably 处理液体墨水的能力在最后 5,000 年享受了高名声，并且广泛地被用来作为文化通讯的一个工具扔墨水进某些人物或图。在这微型评论，我们首先显示出在一把中国刷子的可控制的液体转移的关键怎么躺在刚突现的头发的各向异性的多尺度的结构的特征。然后，绘画从这的灵感，在抽的可控制的液体的应用，高度有效的液体转移和没有模板的打印 microlines 被探讨。我们想象在液体操作的中国刷子和他们的应用的基础在这评论提及，这可以也被扩大到另外的液体阶段功能的材料系统。

Solar-driven high-efficiency remediation of wastewater containing small dye molecules

Remediation of wastewater containing dye molecules is necessary to alleviate the significant threat that poses to human health and the environment.Current treatment technologies are seriously limited by their low efficiency for removing small dye molecules or/and inferior regenerability.Herein,we report a bio-inspired,solar-driven,regenerable separation device capable of separating small dye molecules from the wastewater with high efficiency.The device is composed of porous super-hydrophilic ceramic and carbon nanotubes(CNTs).In comparison with previously reported systems,the resultant device not only achieved a highly promising separation efficiency of>99%for dye-containing wastewater,even for small dye molecules(<1.25 nm),but also demonstrated excellent separation stability and strong resistance to acid/alkali.Moreover,the device demonstrated impressive regenerability on simple calcination and re-coating of the CNT layer after it was blocked.This novel separation device shows potential for application in many fields,such as dye separation,wastewater purification and desalination.

Silica-facilitated proton transfer for high-temperature proton-exchange membrane fuel cells

High-temperature proton-exchange membrane fuel cells(HT-PEMFCs)have shown a broad prospect of applications due to the enhanced reaction kinetics and simplified supporting system.However,the proton conductor,phosphoric acid,tends to poison the active sites of Pt,resulting in high Pt consumption.Herein,Pt nanoparticles anchored on SiO_(2)-modified carbon nanotubes(CNT@SiO_(2)-Pt)are prepared as high-performance cathode catalysts for HT-PEMFCs.The SiO_(2)in CNT@SiO_(2)-Pt can induce the adsorption of phosphoric acid transferring from Pt active sites in the catalytic layer,avoiding the poisoning of the Pt,and the phosphate fixed by SiO_(2)provide a high-speed proton conduction highway for oxygen reduction reactions.Accordingly,The CNT@SiO_(2)-Pt cathode achieve superior power density of 765 mW cm^(−2)(160℃)and 1,061 mW cm^(−2)(220℃)due to the rapid proton-coupled electron process and outstanding stability in HT-PEMFCs.This result provides a new road to resolve the phosphate poisoning for the commercialization of HT-PEMFCs.