Wearable and stretchable conductive polymer composites for strain sensors:How to design a superior one?

Wearable and stretchable strain sensors have potential values in the fields of human motion and health monitoring,flexible electronics,and soft robotic skin.The wearable and stretchable strain sensors can be directly attached to human skin,providing visualized detection for human motions and personal healthcare.Conductive polymer composites(CPC)composed of conductive fillers and flexible polymers have the advantages of high stretchability,good flexibility,superior durability,which can be used to prepare flexible strain sensors with large working strain and outstanding sensitivity.This review has put forward a comprehensive summary on the fabrication methods,advanced mechanisms and strain sensing abilities of CPC strain sensors reported in recent years,especially the sensors with superior performance.Finally,the structural design,bionic function,integration technology and further application of CPC strain sensors are prospected.

CNT/High Mass Loading MnO2/Graphene-Grafted Carbon Cloth Electrodes for High-Energy Asymmetric Supercapacitors

Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.

Metal‐organic frameworks‐derived novel nanostructured electrocatalysts for oxygen evolution reaction

Engineering cost‐effective catalysts with exceptional performance for theelectrochemical oxygen evolution reaction (OER) remains crucial for theaccelerated development of renewable energy techniques, and especially so,given the pivotal role of OER in water electrolysis. On the basis of the metalnodes (clusters) and organic linkers, metal‐organic frameworks (MOFs) andtheir derivatives are rapidly gaining ground in the fabrication of electrocatalysts,with promising catalytic activity and sound durability in OER, thanksto their controllable pore structures, abundant unsaturated active sites of metalion, extensive specific surface area, as well as easily functionalized/modifiedsurfaces. This review presents an in‐depth understanding of the establishedprogress of MOFs‐derived materials for OER electrocatalysis. The materialdesigning strategies of the pristine, monometallic, and multimetallic MOFsbasedcatalysts are summarized to indicate the infinite possibilities of themorphology and the composition of MOF‐derived materials. While emphasisis laid on the essential features of MOF‐derived materials for the electrocatalysisof the corresponding reactions, insights about the applications in OERare discussed. Finally, this paper is concluded by presenting challengesand perspectives for MOF‐derived materials’ future applications in OERelectrocatalysis.

Consecutive hybrid mechanism boosting Na+storage performance of dual-confined SnSe2 in N,Se-doping double-walled hollow carbon spheres

Rationally designed hierarchical structures and heteroatomic doping of carbon are effective strategies to enhance the stability and electrical conductivity of materials.Herein,SnSe_(2)flakes were generated in the double-walled hollow carbon spheres(DWHCSs),in which N and Se atoms were doped in the carbon walls,to construct SnSe_(2)@N,Se-DWHCSs by confined growth and in-situ derivatization.The N and Sedoped DWHCSs can effectively limit the size increase of SnSe_(2),promote ion diffusion kinetics,and buffer volume expansion,which can be proved by electron microscope observation and density functional theory calculation.Consequently,the SnSe_(2)@N,Se-DWHCSs as an anode material for sodium ion batteries(SIBs)demonstrated a distinguished reversible capacity of 322.8 mAh g^(-1)at 5 A g^(-1)after 1000 cycles and a superior rate ability of 235.3 m Ah g^(-1)at an ultrahigh rate of 15 A g^(-1).Furthermore,the structure evolution and electrochemical reaction processes of SnSe2@N,Se-DWHCSs in SIBs were analyzed by exsitu methods,which confirmed the consecutive hybrid mechanism and the phase transition process.

Advanced flexible humidity sensors:structures,techniques,mechanisms and performances

Flexible humidity sensors are widely used in many fields,such as environmental monitoring,agricultural soil moisture content determination,food quality monitoring and healthcare services.Therefore,it is essential to measure humidity accurately and reliably in different conditions.Flexible materials have been the focusing substrates of humidity sensors because of their rich surface chemical properties and structural designability.In addition,flexible materials have superior ductility for different conditions.In this review,we have summarized several sensing mechanisms,processing techniques,sensing layers and substrates for specific humidity sensing requirements.Aadditionally,we have sorted out some cases of flexible humidity sensors based on different functional materials.We hope this paper can contribute to the development of flexible humidity sensors in the future.

Design Strategy for Vulcanization Accelerator of Diphenylguanidine/Cyclodextrin Inclusion Complex for Natural Rubber Latex Foam with Enhancing Performance

Vulcanization is an essential process to obtain high-performance rubber products.Diphenylguanidine(DPG)is often used as the secondary accelerator in the vulcanization process of natural rubber(NR)latex.However,DPG would make NR latex emulsion exhibit gelation,resulting in the negative vulcanization efficiency.In addition,exposure to DPG might lead to some physiological diseases during the production process of DPG doped NR latex.Hydroxypropyl-β-cyclodextrin(HP-β-CD)with the hydrophobic interior and hydrophilic exterior has the advantages of good water solubility,high bioavailability,reliable stability,and low toxicity.In this study,the inclusion complex of diphenylguanidine-hydroxypropyl-β-cyclodextrin(DPG-HP-β-CD)is prepared by bali milling with a host-guest molar ratio of 1:1,which has also been applied to the foaming process of NR latex.The mechanical properties of DPG-HP-β-CD inclusion complex/natural rubber latex foam(DPG-HP-β-CD/NRLF)have been significantly improved,including the tensile strength,elongation at break,hardness,compression set,resilience,and antiaging performance.Further,the usage of DPG has been reduced,leading to the reduction of toxicity and environmental hazards.

Study of a water-soluble supramolecular complex of curcumin andβ-cyclodextrin polymer with electrochemical property and potential anti-cancer activity

As a member of the curcuminoid compound family,curcumin(Cur)has many interesting therapeutic properties.However,its low aqueous solubility and stability have resulted in poor bioavailability and restricted clinical efficacy.Based on size matching,β-cyclodextrin polymer(β-CDP),with its hydrophilic polymer chains and hydrophobic cavities,can form an inclusion complex with Cur.To improve the water solubility and stability of Cur,a simple and eco-friendly grinding method was designed to formβ-CDP inclusion complexes.According to the Boltzmann-Hamel's method and Job's method,the molar ratio of theβ-CD unit inβ-CDP to Cur was determined to be 1:1.The diffusion coefficient and diffusion activation energy of Cur-β-CDP were calculated in an electrochemical study.This supramolecular complex worked well in vitro to inhibit the proliferation of hepatoma carcinoma cells HepG2.Remarkably,this method visibly reduced the undesirable side effects on normal cells,without weakening the anti-cancer activity of the drugs.We expect that the obtained host-guest complex will provide a new approach for delivering natural drug molecules,having low water solubility.