Hydrogels have been extensively studied for applications in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focu...Hydrogels have been extensively studied for applications in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focuses on the modulus, toughness, and deformability. These characteristics play important roles and make great achievements for hydrogel use. In recent years, a growing body of research has concentrated on the fatigue property of hydrogels, which determines their resistance to crack propagation in the networks during cyclic mechanical loads for applications. However, knowledge of hydrogel fatigue behavior remains notably deficient. Here, we present a brief overview of the fatigue behavior of hydrogels, encompassing the general experimental methods to measure the fatigue property and fundamental theoretical calculation models. Then, we highlight multiple strategies to enhance the fatigue resistance of hydrogels. Finally, we present our perspectives on fatigue-resistant hydrogels, outstanding challenges and potential directions for future research.展开更多
CaBi_(2)Nb_(2)O_(9) thin film capacitors were fabricated on SrRuO_(3)-buffered Pt(111)/Ti/Si(100)substrates by adopting a two-step fabrication process.This process combines a low-temperature sputtering deposition with...CaBi_(2)Nb_(2)O_(9) thin film capacitors were fabricated on SrRuO_(3)-buffered Pt(111)/Ti/Si(100)substrates by adopting a two-step fabrication process.This process combines a low-temperature sputtering deposition with a rapid thermal annealing(RTA)to inhibit the grain growth,for the purposes of delaying the polarization saturation and reducing the ferroelectric hysteresis.By using this method,CaBi_(2)Nb_(2)O_(9) thin films with uniformly distributed nanograins were obtained,which display a large recyclable energy density Wrec≈69 J/cm^(3) and a high energy efficiencyη≈82.4%.A superior fatigue-resistance(negligible energy performance degradation after 10^(9) charge-discharge cycles)and a good thermal stability(from-170 to 150℃)have also been achieved.This two-step method can be used to prepare other bismuth layer-structured ferroelectric film capacitors with enhanced energy storage performances.展开更多
Particle-based electrocatalysts need to be glued on an electrode,where fast and slow steps of the reaction are spatially and temporally convoluted near the particles.Since the particles are under continuous electroche...Particle-based electrocatalysts need to be glued on an electrode,where fast and slow steps of the reaction are spatially and temporally convoluted near the particles.Since the particles are under continuous electrochemical stress,decay in their catalytic performance(a.k.a.,fatigue)often occurs due to degradation of the active materials,detachment of particles and deteriorating kinetics.Here we report that these problems are well addressed by fluidizing the particles.The catalysts,instead of being fixed on an electrode,are now fluidized in the electrolyte.Reaction occurs when individual particles collide with the electrode,which collectively delivers a continuous,scalable and stable electrochemical current.Since the catalysts now work in rotation,they experience much faster kinetics and avoid the buildup of excessive electrochemical stress,leading to orders of magnitude higher particle-average efficiency and greatly enhanced fatigue resistance.Proof-ofconcepts are demonstrated using Pt/C catalysts for three well-known reactions,including oxygen evolution,hydrogen evolution and methanol oxidation reactions,all of which suffer severe performance decay using Pt/C under different mechanisms.Fluidized electrocatalysis breaks the spatial and temporal continuum of electrocatalytic reactions,and makes them drastically more fatigue resistant.It is material-and reaction-agnostic,and should be a general approach to enhance electrocatalytic reactions.展开更多
基金the National Natural Science Foundation of China(Nos.T2222019,11974174,and 11934008)the National Key R&D Program of China(No.2020YFA0908100).
文摘Hydrogels have been extensively studied for applications in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focuses on the modulus, toughness, and deformability. These characteristics play important roles and make great achievements for hydrogel use. In recent years, a growing body of research has concentrated on the fatigue property of hydrogels, which determines their resistance to crack propagation in the networks during cyclic mechanical loads for applications. However, knowledge of hydrogel fatigue behavior remains notably deficient. Here, we present a brief overview of the fatigue behavior of hydrogels, encompassing the general experimental methods to measure the fatigue property and fundamental theoretical calculation models. Then, we highlight multiple strategies to enhance the fatigue resistance of hydrogels. Finally, we present our perspectives on fatigue-resistant hydrogels, outstanding challenges and potential directions for future research.
基金the financial support of the National Natural Science Foundation of China(Grant Nos.51772175 and 51872166)the Nano Projects of Suzhou City(Grant No.ZXG201445)+2 种基金the support from the Seed Funding for Top Talents in Qilu University of Technology(Shandong Academy of Sciences)the International Cooperation Research Project of Qilu University of Technology(Grant No.QLUTGJHZ2018003)the Independent Innovation Foundation of Shandong University(Grant Nos.2018JC045 and 2017ZD008).
文摘CaBi_(2)Nb_(2)O_(9) thin film capacitors were fabricated on SrRuO_(3)-buffered Pt(111)/Ti/Si(100)substrates by adopting a two-step fabrication process.This process combines a low-temperature sputtering deposition with a rapid thermal annealing(RTA)to inhibit the grain growth,for the purposes of delaying the polarization saturation and reducing the ferroelectric hysteresis.By using this method,CaBi_(2)Nb_(2)O_(9) thin films with uniformly distributed nanograins were obtained,which display a large recyclable energy density Wrec≈69 J/cm^(3) and a high energy efficiencyη≈82.4%.A superior fatigue-resistance(negligible energy performance degradation after 10^(9) charge-discharge cycles)and a good thermal stability(from-170 to 150℃)have also been achieved.This two-step method can be used to prepare other bismuth layer-structured ferroelectric film capacitors with enhanced energy storage performances.
基金Y.Z.and Y.K.thanks University of Electronic Science and Technology of China(UESTC)for supporting their academic visit and research activities at Northwestern that generated most data reported in this work.Y.Z.also thanks her new faculty startup fund at Hunan University,which supported her to reproduce the work and generate some new data during the review of the manuscript.J.H.thanks the support from the Robert R.McCormick School of Engineering and Applied Science at Northwestern,and the Humboldt Research Award,an earlier Guggenheim Fellowship and an earlier gift fund from the Sony Corporation,which offered the intellectual freedom for him to indulge in new and unfunded research ideas during his academic leaves and conceptualize this work.This work made use of the TEM facility of Northwestern University’s NUANCE Center,which has received support from the Soft and Hybrid Nanotechnology Experimental(SHyNE)Resource(NSF ECCS-1542205)the MRSEC program(NSF DMR-1720139)at the Materials Research Center,the International Institute for Nanotechnology(IIN),the Keck Foundation,and the State of Illinois,through the IIN.The authors thank Luke Prestowitz,Alane Lim,Kevin Chiou,Prof.Markus Antonietti from Max Planck Institute of Colloids and Interfaces for helpful discussions.We also thank the anonymous reviewers for their helpful comments and suggestions.
文摘Particle-based electrocatalysts need to be glued on an electrode,where fast and slow steps of the reaction are spatially and temporally convoluted near the particles.Since the particles are under continuous electrochemical stress,decay in their catalytic performance(a.k.a.,fatigue)often occurs due to degradation of the active materials,detachment of particles and deteriorating kinetics.Here we report that these problems are well addressed by fluidizing the particles.The catalysts,instead of being fixed on an electrode,are now fluidized in the electrolyte.Reaction occurs when individual particles collide with the electrode,which collectively delivers a continuous,scalable and stable electrochemical current.Since the catalysts now work in rotation,they experience much faster kinetics and avoid the buildup of excessive electrochemical stress,leading to orders of magnitude higher particle-average efficiency and greatly enhanced fatigue resistance.Proof-ofconcepts are demonstrated using Pt/C catalysts for three well-known reactions,including oxygen evolution,hydrogen evolution and methanol oxidation reactions,all of which suffer severe performance decay using Pt/C under different mechanisms.Fluidized electrocatalysis breaks the spatial and temporal continuum of electrocatalytic reactions,and makes them drastically more fatigue resistant.It is material-and reaction-agnostic,and should be a general approach to enhance electrocatalytic reactions.
