Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic ...Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities,existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity.Here,an ultrasensitive,highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers.The bilayer sensor consists of an aligned carbon nanotube(CNT)array assembled on top of a periodically wrinkled and cracked CNT-graphene oxide film.The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched,leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100%strain.The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3,to the benefit of accurate detection of loading directions by the multidirectional sensor.This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity,selectivity,and stretchability,demonstrating promising applications in full-range,multi-axis human motion detection for wearable electronics and smart robotics.展开更多
An optimized graphene/RuO2/S composite is prepared by hydrothermal growth of RuO2 particles on graphene oxide sheets as the positive electrode for rechargeable lithium-sulfur batteries. The electrode with 6.1 wt% RuO2...An optimized graphene/RuO2/S composite is prepared by hydrothermal growth of RuO2 particles on graphene oxide sheets as the positive electrode for rechargeable lithium-sulfur batteries. The electrode with 6.1 wt% RuO2 nanocrystals and a high sulfur content of 79.0 wt% delivers an optimal electrochemical performance with high residual capacities of 508 mAh g-1 after 200 cycles and 389 m Ah g-1 after800 cycles at 1 C with a low capacity decay of 0.054%. The RuO2 nanocrystals promote the redox reaction kinetics and facilitate the transformation of sulfur chemistry, leading to large improvements in reversibility and rate capability of the composite electrode. The density functional theory calculations signify the formation of Li–O and Ru–S bonds through chemical interactions between RuO2 and Li polysulfides while the adsorption energies between graphene and polysulfide species are much higher in the presence of RuO2 than that of the neat graphene acting alone. These discoveries support the efficient entrapment of polysulfides by the composite electrode to the benefit of enhanced cyclic stability of the battery.展开更多
Sn has been considered one of the most promising metallic anode materials for lithium-ion batteries(LIBs)because of its high specific capacity.Herein,we report a novel amorphous tin-titanium-ethylene glycol(Sn-Ti-EG)b...Sn has been considered one of the most promising metallic anode materials for lithium-ion batteries(LIBs)because of its high specific capacity.Herein,we report a novel amorphous tin-titanium-ethylene glycol(Sn-Ti-EG)bimetal organic compound as an anode for LIBs.The Sn-Ti-EG electrode exhibits exceptional cyclic stability with high Li-ion storage capacity.Even after 700 cycles at a current density of 1.0 A g−1,the anode maintains a capacity of 345 mAh g−1.The unique bimetal organic structure of the Sn-Ti-EG anode and the strong coordination interaction between Sn/Ti and O within the framework effectively suppress the aggrega-tion of Sn atoms,eliminating the usual pulverization of bulk Sn through volume expansion.Furthermore,the Sn M-edge of the X-ray absorption near-edge structure spectra obtained using soft X-ray absorption spec-troscopy signifies the conversion of Sn2+ions into Sn0 during the initial lithiation process,which is reversible upon delithiation.These findings reveal that Sn is one of the most active components that account for the excellent electrochemical performance of the Sn-Ti-EG electrode,whereas Ti has no practical contribution to the capacity of the electrode.The reversible formation of organic functional groups on the solid electrolyte interphase is also partly responsible for its cyclic stability.展开更多
Given the abundance of potassium resources,potassium-ion batteries are considered a low-cost alternative to lithium-ion types.However,their electrochemical performance remains rather unsatisfactory because potassium i...Given the abundance of potassium resources,potassium-ion batteries are considered a low-cost alternative to lithium-ion types.However,their electrochemical performance remains rather unsatisfactory because potassium ions have sluggish kinetics and large ionic radius.In this study,NiCo_(2)Se_(4)nanotube spheres are synthesized as efficient potassium storage hosts via a facile two-step hydrothermal process.The rationally designed electrode has various ameliorating morphological and functional features,including the following:(i)A hollow structure allows for relief of the volume expansion while offering an excellent electrochemical reac-tivity to accelerate the conversion kinetics;(ii)a high electrical conductivity for enhanced electron transfer;and(iii)myriad vacancies to supply active sites for electrochemical reactions.As such,the electrode delivers an initial reversible capacity of 458.1 mAh g^(−1)and retains 346.6 mAh g^(−1)after 300 cycles at 0.03 A g^(−1).The electrode sustains a high capacity of 101.4 mAh g^(−1)even at a high current density of 5 A g^(−1)and outperforms the majority of state-of-the-art anodes in terms of both cyclic capacity and rate capability,especially at above 1.0 A g^(−1).This study not only proves bimetallic selenides are promising candidates for potassium storage devices but also offers new insight into the rational design of electrode materials for high-rate potassium-ion batteries.展开更多
Electrically conductive porous structures are ideal candidates for lightweight and absorption-dominant electromagnetic interference(EMI)shielding.In this review,we summarize the recent progress in developing porous co...Electrically conductive porous structures are ideal candidates for lightweight and absorption-dominant electromagnetic interference(EMI)shielding.In this review,we summarize the recent progress in developing porous composites and structures from emerging two-dimensional(2D)graphene and MXene nanosheets for EMI shielding applications.Important properties contributing to various energy loss mechanisms are probed with a critical discussion on their correlations with EMI shielding performance.Technological approaches to constructing bulk porous structures,such as 2D porous films,three-dimensional(3D)aerogels and foams,and hydrogels,are compared to highlight important material and processing parameters required to achieve optimal microstructures.A comprehensive comparison of EMI shielding performance is also carried out to elucidate the effects of different assembly techniques and microstructures.Distinctive multifunctional applications in adaptive EMI shielding,mechanical force attenuation,thermal management,and wearable devices are introduced,underlining the importance of unique compositions and microstructures of porous composites.The process–structure–property relationships established in this review would offer valuable guidance and insights into the design of lightweight EMI shielding materials.展开更多
Flexible and easily reconfigurable supercapacitors show great promise for application in wearable electronics. In this study, multiwall C nanotubes （CNTs） decorated with hierarchical ultrathin zinc sulfide （ZnS） n...Flexible and easily reconfigurable supercapacitors show great promise for application in wearable electronics. In this study, multiwall C nanotubes （CNTs） decorated with hierarchical ultrathin zinc sulfide （ZnS） nanosheets （ZnS@CNT） are synthesized via a facile method. The resulting ZnS@CNT electrode, which delivers a high specific capacitance of 347.3 F·g^-1 and an excellent cycling stability, can function as a high-performance electrode for a flexible all-solid-state supercapacitor using a polymer gel electrolyte. Our device exhibits a remarkable specific capacitance of 159.6 F·g^-1, a high energy density of 22.3 W·h·kg^-1, and a power density of 5 kW·kg^-1 It also has high electrochemical performance even under bending or twisting. The all-solid-state supercapacitors can be easily integrated in series to power different commercial light-emitting diodes without an external bias voltage.展开更多
Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect ...Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect bandgap in multilayer structures,degrades their performance when used as IR photodetectors.In this work,we utilize the fact that few-layer MoTe2 flake has a near-IR(NIR)bandgap and demonstrate a^60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface.Such gold hollow nanorods have distinct absorption peak located also at the NIR regime,therefore induces strong resonance,benefitting NIR absorption in MoTe2,resulting in strong near-field enhancement.With the evidence from steady and transient state optical spectra,we confirm that the enhancement of NIR response originates only photon absorption,rather than electron transport at interfaces as observed in other heterostructures,therefore,precluding the requirement of high-quality interfaces for commercial applications.展开更多
基金This project was financially supported by the Research Grants Council(GRF Projects:16229216,16209917,16205517)the Innovation and Technology Commission(ITS/012/19)of Hong Kong SAR.
文摘Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities,existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity.Here,an ultrasensitive,highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers.The bilayer sensor consists of an aligned carbon nanotube(CNT)array assembled on top of a periodically wrinkled and cracked CNT-graphene oxide film.The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched,leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100%strain.The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3,to the benefit of accurate detection of loading directions by the multidirectional sensor.This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity,selectivity,and stretchability,demonstrating promising applications in full-range,multi-axis human motion detection for wearable electronics and smart robotics.
基金financially supported by the Research Grants Council(GRF Projects 16212814 and 16208718)the Innovation and Technology Commission(ITF Project Code ITS/001/17)of Hong Kong SAR+1 种基金the technical assistance from the Materials Characterization and Preparation Facilities(MCPF)the Advanced Engineering Materials Facilities(AEMF)of HKUST
文摘An optimized graphene/RuO2/S composite is prepared by hydrothermal growth of RuO2 particles on graphene oxide sheets as the positive electrode for rechargeable lithium-sulfur batteries. The electrode with 6.1 wt% RuO2 nanocrystals and a high sulfur content of 79.0 wt% delivers an optimal electrochemical performance with high residual capacities of 508 mAh g-1 after 200 cycles and 389 m Ah g-1 after800 cycles at 1 C with a low capacity decay of 0.054%. The RuO2 nanocrystals promote the redox reaction kinetics and facilitate the transformation of sulfur chemistry, leading to large improvements in reversibility and rate capability of the composite electrode. The density functional theory calculations signify the formation of Li–O and Ru–S bonds through chemical interactions between RuO2 and Li polysulfides while the adsorption energies between graphene and polysulfide species are much higher in the presence of RuO2 than that of the neat graphene acting alone. These discoveries support the efficient entrapment of polysulfides by the composite electrode to the benefit of enhanced cyclic stability of the battery.
基金the National Natural Science Foundation of China(52277219,61974072,52032005)the Project of State Key Laboratory of Organic Electronics and Information Displays,Nanjing University of Posts and Telecommunications(GZR2022010024)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_0992)JKK is grateful for the financial support(FSU 2023-022,PD#8295)from Khalifa University.
文摘Sn has been considered one of the most promising metallic anode materials for lithium-ion batteries(LIBs)because of its high specific capacity.Herein,we report a novel amorphous tin-titanium-ethylene glycol(Sn-Ti-EG)bimetal organic compound as an anode for LIBs.The Sn-Ti-EG electrode exhibits exceptional cyclic stability with high Li-ion storage capacity.Even after 700 cycles at a current density of 1.0 A g−1,the anode maintains a capacity of 345 mAh g−1.The unique bimetal organic structure of the Sn-Ti-EG anode and the strong coordination interaction between Sn/Ti and O within the framework effectively suppress the aggrega-tion of Sn atoms,eliminating the usual pulverization of bulk Sn through volume expansion.Furthermore,the Sn M-edge of the X-ray absorption near-edge structure spectra obtained using soft X-ray absorption spec-troscopy signifies the conversion of Sn2+ions into Sn0 during the initial lithiation process,which is reversible upon delithiation.These findings reveal that Sn is one of the most active components that account for the excellent electrochemical performance of the Sn-Ti-EG electrode,whereas Ti has no practical contribution to the capacity of the electrode.The reversible formation of organic functional groups on the solid electrolyte interphase is also partly responsible for its cyclic stability.
基金supported by the Research Grants Council(GRF project 16208718)the Innovation and Technology Commission(ITF project ITS/001/17)of Hong Kong SARthe National Natural Science Foundation of China(No.52202297).
文摘Given the abundance of potassium resources,potassium-ion batteries are considered a low-cost alternative to lithium-ion types.However,their electrochemical performance remains rather unsatisfactory because potassium ions have sluggish kinetics and large ionic radius.In this study,NiCo_(2)Se_(4)nanotube spheres are synthesized as efficient potassium storage hosts via a facile two-step hydrothermal process.The rationally designed electrode has various ameliorating morphological and functional features,including the following:(i)A hollow structure allows for relief of the volume expansion while offering an excellent electrochemical reac-tivity to accelerate the conversion kinetics;(ii)a high electrical conductivity for enhanced electron transfer;and(iii)myriad vacancies to supply active sites for electrochemical reactions.As such,the electrode delivers an initial reversible capacity of 458.1 mAh g^(−1)and retains 346.6 mAh g^(−1)after 300 cycles at 0.03 A g^(−1).The electrode sustains a high capacity of 101.4 mAh g^(−1)even at a high current density of 5 A g^(−1)and outperforms the majority of state-of-the-art anodes in terms of both cyclic capacity and rate capability,especially at above 1.0 A g^(−1).This study not only proves bimetallic selenides are promising candidates for potassium storage devices but also offers new insight into the rational design of electrode materials for high-rate potassium-ion batteries.
基金This project was financially supported by the Research Grants Council(GRF Projects:16205517,16209917,and 16200720)the Innovation and Technology Commission(ITS/012/19)of Hong Kong SAR,and start-up fund for new recruits of PolyU(Nos.P0038855 and P0038858)This project was also supported by the Research Institute for Sports Science and Technology of PolyU(No.P0043535).
文摘Electrically conductive porous structures are ideal candidates for lightweight and absorption-dominant electromagnetic interference(EMI)shielding.In this review,we summarize the recent progress in developing porous composites and structures from emerging two-dimensional(2D)graphene and MXene nanosheets for EMI shielding applications.Important properties contributing to various energy loss mechanisms are probed with a critical discussion on their correlations with EMI shielding performance.Technological approaches to constructing bulk porous structures,such as 2D porous films,three-dimensional(3D)aerogels and foams,and hydrogels,are compared to highlight important material and processing parameters required to achieve optimal microstructures.A comprehensive comparison of EMI shielding performance is also carried out to elucidate the effects of different assembly techniques and microstructures.Distinctive multifunctional applications in adaptive EMI shielding,mechanical force attenuation,thermal management,and wearable devices are introduced,underlining the importance of unique compositions and microstructures of porous composites.The process–structure–property relationships established in this review would offer valuable guidance and insights into the design of lightweight EMI shielding materials.
基金This work is financially supported by the National Natural Science Foundation of China （Nos. 61574122, 51502257, 21373107 and U1304108）, the Innovative Research Team （in Science and Technology） in Universities in Henan Province （No. 13IRTSTHN018）, the Key Project of Henan Educational Committee （No. 15A140035）, and the program for Science ＆ Technology Innovation Talents in Universities of Henan Province （No. 15HASTIT018）.
文摘Flexible and easily reconfigurable supercapacitors show great promise for application in wearable electronics. In this study, multiwall C nanotubes （CNTs） decorated with hierarchical ultrathin zinc sulfide （ZnS） nanosheets （ZnS@CNT） are synthesized via a facile method. The resulting ZnS@CNT electrode, which delivers a high specific capacitance of 347.3 F·g^-1 and an excellent cycling stability, can function as a high-performance electrode for a flexible all-solid-state supercapacitor using a polymer gel electrolyte. Our device exhibits a remarkable specific capacitance of 159.6 F·g^-1, a high energy density of 22.3 W·h·kg^-1, and a power density of 5 kW·kg^-1 It also has high electrochemical performance even under bending or twisting. The all-solid-state supercapacitors can be easily integrated in series to power different commercial light-emitting diodes without an external bias voltage.
基金This project was supported by the Research Grant Council of Hong Kong SAR(No.1620441)NSFC-RGC Joint Research Scheme(No.N_HKUST607/17)+4 种基金the Innovation and Technology Commission(No.ITC-CNERC14SC01)the Zhongshan Municipal Bureau of Science&Technology(No.ZSST19EG03)National Natural Science Foundation of China(NSFC)(Nos.11825203,51872100,21825103,21501060 and 51727809)National Basic Research Program of China(Nos.2015CB932600 and 2019kfyRCPY059)Foundation of Shenzhen Science and Technology Innovation Committee(No.JCYJ20180504170444967).
文摘Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect bandgap in multilayer structures,degrades their performance when used as IR photodetectors.In this work,we utilize the fact that few-layer MoTe2 flake has a near-IR(NIR)bandgap and demonstrate a^60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface.Such gold hollow nanorods have distinct absorption peak located also at the NIR regime,therefore induces strong resonance,benefitting NIR absorption in MoTe2,resulting in strong near-field enhancement.With the evidence from steady and transient state optical spectra,we confirm that the enhancement of NIR response originates only photon absorption,rather than electron transport at interfaces as observed in other heterostructures,therefore,precluding the requirement of high-quality interfaces for commercial applications.
