The rapid advancement of information technology has heightened interest in complementary devices and circuits.Conventional p-type semiconductors often lack sufficient electrical performance,thus prompting the search f...The rapid advancement of information technology has heightened interest in complementary devices and circuits.Conventional p-type semiconductors often lack sufficient electrical performance,thus prompting the search for new materials with high hole mobility and long-term stability.Elemental tellurium(Te),featuring a one-dimensional chiral atomic structure,has emerged as a promising candidate due to its narrow bandgap,high hole mobility,and versatility in industrial applications,particularly in electronics and renewable energy.This review highlights recent progress in Te nanostructures and related devices,focusing on synthesis methods,including vapor deposition and hydrothermal synthesis,which produce Te nanowires,nanorods,and other nanostructures.Critical applications in photodetectors,gas sensors,and energy harvesting devices are discussed,with a special emphasis on their role within the internet of things(IoT)framework,a rapidly growing field that is reshaping our technological landscape.The prospects and potential applications of Te-based technologies are also highlighted.展开更多
The emergence of light-tunable synaptic transistors provides opportunities to break through the von Neumann bottleneck and enable neuromorphic computing.Herein,a multifunctional synaptic transistor is constructed by u...The emergence of light-tunable synaptic transistors provides opportunities to break through the von Neumann bottleneck and enable neuromorphic computing.Herein,a multifunctional synaptic transistor is constructed by using 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8-BTBT)and indium gallium arsenide(InGaAs)nanowires(NWs)hybrid heterojunction thin film as the active layer.Under illumination,the Type-I C8-BTBT/InGaAs NWs heterojunction would make the dissociated photogenerated excitons more difficult to recombine.The persistent photoconductivity caused by charge trapping can then be used to mimic photosynaptic behaviors,including excitatory postsynaptic current,long/short-term memory and Pavlovian learning.Furthermore,a high classification accuracy of 89.72%can be achieved through the single-layer-perceptron hardware-based neural network built from C8-BTBT/InGaAs NWs synaptic transistors.Thus,this work could provide new insights into the fabrication of high-performance optoelectronic synaptic devices.展开更多
Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of thes...Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of these properties.Here,a self-assembling nacre-like polymer composite is designed to achieve ex-tremely tough with increasing strength.This special design significantly improved polymer’s mechanical properties,including an ultra-high fracture strain of 1180%,a tensile strength of 55.4 MPa and a toughness of 506.9 MJ/m^(3),which far exceed the highest values previously reported for polymer composites.This ex-cellent combination of properties can be attributed to a novel toughening mechanism,achieved by the synergy of the domain-limiting effect of metallic glass fragments with the strain-gradient-induced orien-tation and crystallisation within the polymer during stretching.Our approach opens a promising avenue for designing robust polymer materials in armour and aerospace engineering for a range of innovative applications.展开更多
Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling elec...Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.展开更多
Developing new methodologies to produce clean and renewable energy resources is pivotal for carbon-neutral initiatives.Hydrogen(H2)is considered as an ideal energy resource due to its nontoxic,pollution-free,high util...Developing new methodologies to produce clean and renewable energy resources is pivotal for carbon-neutral initiatives.Hydrogen(H2)is considered as an ideal energy resource due to its nontoxic,pollution-free,high utilization rate,and high calorific combustion value.Electrolysis of water driven by the electricity generated from renewable and clean energy sources(e.g.,solar energy,wind energy)to produce hydrogen attracts great efforts for hydrogen production with high purity.Recently,the breakthrough of the catalyst activity limit for the hydrogen evolution reaction(HER)catalysts has received extensive attention.Comparatively,fewer reviews have focused on the long-term stability of HER catalysts,which is indeed decisive for large-scale electrolytic industrialization.Therefore,a systematic summary concentrated on the durability of HER electrocatalysts would provide a fundamental understanding of the electrocatalytic performance for practical applications and offer new opportunities for the rational design of the highly performed HER electrocatalysts.This review summarizes the research progress toward the HER stability of precious metals,transition metals,and metal-free electrocatalysts in the past few years.It discusses the challenges in the stability of HER electrocatalysts and the future perspectives.We anticipate that it would provide a valuable basis for designing robust HER electrocatalysts.展开更多
To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption...To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption, simplification of device fabrication as well as optimization of device structure and geometry, are required. The usage of 1D nanomaterials is attractive due to the outstanding light coupling effect, the ease of fabrication, and integration with one-dimensional(1-D) semiconductor materials. The light absorption efficiency can be enhanced significantly, and the corresponding light-toelectricity conversion efficiency can be as high as their bulk counterparts. Also, the amount of active materials used can be reduced. This review summarizes the recent development of 1-D nanomaterials for photovoltaic applications, including the anti-reflection, the light absorption,the minority diffusion, and the semiconductor junction properties. With solid progress and prospect shown in the past 10 years, 1-D semiconductor nanomaterials are attractive and promising for the realization of high-efficiency and low-cost solar cells.展开更多
Hybrid organolead halide perovskites have attracted tremendous attention due to their recent success as high efficiency solar cell materials and their fascinating material properties uniquely suitable for optoelectron...Hybrid organolead halide perovskites have attracted tremendous attention due to their recent success as high efficiency solar cell materials and their fascinating material properties uniquely suitable for optoelectronic devices. However, the poor ambient and operational stability as well as the concern of lead toxicity greatly hamper their practical utilization. In this work, crystalline, all-inorganic and lead-free Cs_(3)Sb_(2)I_(9) perovskite microplates are successfully synthesized by a two-step chemical vapor deposition method. As compared with other typical lead-free perovskite materials, the Cs_(3)Sb_(2)I_(9) microplates demonstrate excellent optoelectronic properties, including substantial enhancements in the Stokes shift, exciton binding energy and electron-phonon coupling. Simple photoconductive devices fabricated using these microplates exhibit an ultra-fast response with the rise and decay time constants down to 96 and 58 µs, respectively. This respectable photoconductor performance can be regarded as a record among all the lead-free perovskite materials. Importantly, these photodetectors show superior thermal stability in a wide temperature range, capable to function reversibly between 80 and 380 K, indicating their robustness to operate under both low and high temperatures. All these results evidently suggest the technological potential of inorganic lead-free Cs_(3)Sb_(2)I_(9) perovskite microplates for next-generation high-performance optoelectronic devices.展开更多
InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial ...InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial InAs nanowires,however,has often relied on the use of Au colloids which is non-CMOS compatible.Here,we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO_(2) substrates.The nanowires show superb electrical properties with field-effect electron mobility~2700 cm^(2)/Vs and ION/IOFF>10^(3).The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance,“printable”transistors,capable of delivering 510 mA ON currents(~400 nanowires).展开更多
Designing highly efficient and low-cost electrocatalysts for oxygen evolution reaction is important for many renewable energy applications.In particular,strain engineering has been demonstrated as a powerful strategy ...Designing highly efficient and low-cost electrocatalysts for oxygen evolution reaction is important for many renewable energy applications.In particular,strain engineering has been demonstrated as a powerful strategy to enhance the electrochemical performance of catalysts;however,the required complex catalyst preparation process restricts the implementation of strain engineering.Herein,we report a simple self-template method to prepare hierarchical porous Co_(3)O_(4)nanowires(PNWs)with tunable compressive strain via thermal-oxidation-transformation of easily prepared oxalic acid-cobalt nitrate(Co(NO_(3))_(2))composite nanowires.Based on the complementary theoretical and experimental studies,the selection of proper solvents in the catalyst preparation is not only vital for the hierarchical structural evolution of Co_(3)O_(4) but also for regulating their compressive surface strain.Because of the rich surface active sites and optimized electronic Co d band centers,the PNWs exhibit the excellent activity and stability for oxygen evolution reaction,delivering a low overpotential of 319 mV at 10 mA·cm^(−2)in 1 M KOH with a mass loading 0.553 mg·cm^(−2),which is even better than the noble metal catalyst of RuO_(2).This work provides a cost-effective example of porous Co_(3)O_(4)nanowire preparation as well as a promising method for modification of surface strain for the enhanced electrochemical performance.展开更多
Due to the exciting photoelectric properties,better stability,and environmental-friendly nature,all-inorganic halide perovskites(AIHPs),especially the lead-free perovskites,have attracted worldwide attention.However,t...Due to the exciting photoelectric properties,better stability,and environmental-friendly nature,all-inorganic halide perovskites(AIHPs),especially the lead-free perovskites,have attracted worldwide attention.However,the film quality of AIHPs fabricated by typical spin-coating and subsequent high-temperature annealing is still not satisfactory,restricting their further development.Herein,we demonstrate a simple low-temperature solution-processed drop-casting method to achieve highly-crystalline cubic CsPbBr_(3)and lead-free layer-structured Cs_(3)Sb_(2)I_(9)microcrystals(MCs).This drop-casting technique not only consumes the less amount of precursor solution but also eliminates the high-temperature annealing as compared with those of spin coating.When these MCs are configured into photodetectors,they exhibit superior device performance,which is in distinct contrast to the one of spin-coated counterparts.Specifically,the responsivity of CsPbBr_(3)MCs is found to be as large as 8,990 mA/W,being 13 times larger than the spin-coated films and even better than many state-of-the-art solution-processed AIHPs devices.This device performance enhancement is attributed to the better film quality and phase purity obtained by the drop-casting method.All these results can evidently fill the“technology gap”for further enhancing the material quality of solution-processed AIHPs and breaking down the barriers that hinder the development of AIHPs based optoelectronic devices.展开更多
With luminescent concentrators,the high quantum yield luminescence emitted by embedded chromophores,featuring a broad absorption spectrum,can be well-tuned to match the peak response of integrated photodetectors.This ...With luminescent concentrators,the high quantum yield luminescence emitted by embedded chromophores,featuring a broad absorption spectrum,can be well-tuned to match the peak response of integrated photodetectors.This integration can substantially enhance the device photoresponse all the way from deep UV to near-IR.展开更多
To date,due to the excellent electrochemical inertness,superb electrical conductivity and good mechanical stability in both aqueous and nonaqueous solutions,platinum(Pt)has been widely employed as counter electrode ma...To date,due to the excellent electrochemical inertness,superb electrical conductivity and good mechanical stability in both aqueous and nonaqueous solutions,platinum(Pt)has been widely employed as counter electrode material in three-electrode setups to perform electroanalytical chemistry.However,recent reports have revealed that the use of Pt based counter electrodes展开更多
Due to the enhanced ambient structural stability and excellent optoelectronic properties, all-inorganic metal halide perovskite nanowires have become one of the most attractive candidates for flexible electronics, pho...Due to the enhanced ambient structural stability and excellent optoelectronic properties, all-inorganic metal halide perovskite nanowires have become one of the most attractive candidates for flexible electronics, photovoltaics and optoelectronics. Their elastic property and mechanical robustness become the key factors for device applications under realistic service conditions with various mechanical loadings. Here, we demonstrate that high tensile elastic strain (∼ 4% to ∼ 5.1%) can be achieved in vapor-liquid-solid-grown single-crystalline CsPbBr_(3) nanowires through in situ scanning electron microscope (SEM) buckling experiments. Such high flexural elasticity can be attributed to the structural defect-scarce, smooth surface, single-crystallinity and nanomechanical size effect of CsPbBr_(3) nanowires. The mechanical reliability of CsPbBr_(3) nanowire-based flexible photodetectors was examined by cyclic bending tests, with no noticeable performance deterioration observed after 5,000 cycles. The above results suggest great application potential for using all-inorganic perovskite nanowires in flexible electronics and energy harvesting systems.展开更多
Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their pho...Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their photoelectric device performance is still not satisfactory.Herein,we report a facile solution-process method to synthesize the recently most popular lead-free halide double perovskite,MA_(2)Ag Bi Br_(6),and its all-inorganic counterpart,Cs_(2)Ag Bi Br_(6).The obtained MA_(2)Ag Bi Br_(6)and Cs_(2)Ag Bi Br_(6)films exhibit the microplatelet morphology with excellent crystallinity,distinctly contrasting the ones fabricated by the conventional spin-coating method.Once fabricated into simple photodetectors,the Cs_(2)Ag Bi Br_(6)microplatelet devices yield a respectable responsivity of 245 m A W^(-1) that is two orders of magnitude larger than that of the spin-coated films.More importantly,the response speed of the Cs_(2)Ag Bi Br_(6)microplatelets device is as fast as 145μs,which is higher than most of the values reported in the community of halide double perovskites.When subjected to the thermal stability testing,the Cs_(2)Ag Bi Br_(6)microplatelet device can maintain its initial performance after heating to 160℃ and cooling down to room temperature in the ambient environment.All these results suggest that the facile solution-process method is capable of fabricating high-quality lead-free double perovskites,enabling their advanced device applications.展开更多
All-inorganic halide perovskites(IHP),CsPbX_(3)(X=Cl,Br,I)exhibiting efficient optical emissions within the spectral range of 410 to 730 nm are potential candidates for many optoelectronic devices.Anion alloying of th...All-inorganic halide perovskites(IHP),CsPbX_(3)(X=Cl,Br,I)exhibiting efficient optical emissions within the spectral range of 410 to 730 nm are potential candidates for many optoelectronic devices.Anion alloying of these IHPs is expected to achieve tunable emission wavelength covering the entire visible spectrum.Here,we developed a two-step chemical vapor deposition(CVD)process for growing quaternary IHP CsPbX_(3)(X=Cl/Br and Br/I)alloys.By exploiting the fast diffusion of halide anions in IHPs,the alloy composition can be precisely controlled by the growth time of the respective layers once the growth of the individual ternary IHP is optimized.Hence complexities in the multi-parameter optimization in the conventional CVD growth of quaternary alloys can be mitigated.Using this process,we synthesized single crystalline,homogeneous and thermally stable CsPbCl3_((1−X))Br_(3x)and CsPbBr3_((1−X))I_(3x)perovskites alloy microplates and demonstrated continuously tunable emission covering the spectrum from 428 to 715 nm by varying the halide compositions in the alloys.These alloy microplates also exhibit room temperature amplified spontaneous emissions(ASE)along with strong photonic discharges from the microplate’s edges and hence are potentially useful as a gain medium as well as optical cavities for emissions with wavelengths covering the visible spectrum.展开更多
Due to the ultra-thin nature and moderate carrier mobility,semiconducting two-dimensional(2D)materials have attracted extensive attention for next-generation electronics.However,the gate bias stress instability and hy...Due to the ultra-thin nature and moderate carrier mobility,semiconducting two-dimensional(2D)materials have attracted extensive attention for next-generation electronics.However,the gate bias stress instability and hysteresis are always observed in these 2D materials-based transistors that significantly degrade their reliability for practical applications.Herein,the origin of gate bias stress instability and hysteresis for chemical vapor deposited monolayer WS2 transistors are investigated carefully.The transistor performance is found to be strongly affected by the gate bias stress time,sweeping rate and range,and temperature.Based on the systematical study and complementary analysis,charge trapping is determined to be the major contribution for these observed phenomena.Importantly,due to these charge trapping effects,the channel current is observed to decrease with time;hence,a rate equation,considering the charge trapping and time decay effect of current,is proposed and developed to model the phenomena with excellent consistency with experimental data.All these results do not only indicate the validity of the charge trapping model,but also confirm the hysteresis being indeed caused by charge trapping.Evidently,this simple model provides a sufficient explanation for the charge trapping induced gate bias stress instability and hysteresis in monolayer WS2 transistors,which can be also applicable to other kinds of transistors.展开更多
Organic-inorganic halide perovskite,as a low-cost,solution-processable material with remarkable optoelectronic properties,is ideal candidate to fabricate high-performance photodetectors and is expected to significantl...Organic-inorganic halide perovskite,as a low-cost,solution-processable material with remarkable optoelectronic properties,is ideal candidate to fabricate high-performance photodetectors and is expected to significantly reduce device costs.Compared to the common Dion-Jacobson and Ruddlesden-Popper two-dimensional(2D)layered hybrid perovskite compounds,the perovskites with alternating cations in the interlayer(ACI)phase show higher crystal symmetry and narrower optical bandgaps,which exhibit great potential for excellent photodetection performance.Herein,we report a high-performance photodetector based on the 2D bilayered hybrid lead halide perovskite single crystal with the ACI phase(GAMA_(2)Pb_(2)I_(7);GA=C(NH_(2))_(3)and MA=CH_(3)NH_(3)).The single-crystal photodetector exhibits high photoresponsivity of 1.56,2.54,and 2.60 A/W for incident light wavelengths of 405,532,and 635 nm under 9.82 nW,respectively,together with the correspondingly high detectivity values of 1.86×10^(12),3.04×10^(12),and 3.11×10^(12)Jones under the same operating conditions.Meanwhile,a high-resolution imaging sensor is built based on the GAMA_(2)Pb_(2)I_(7)single-crystal photodetector,confirming the high stability and photosensitivity of the imaging system.These results show that the 2D hybrid lead halide perovskites with alternating interlayer cations are promising for high-performance visible light photodetectors and imaging systems.展开更多
基金supported by a fellowship award from the Research Grants Council of the Hong Kong Special Administrative Region,China(CityU RFS2021−1S04)the Innovation and Technology Fund(MHP/044/23)from the Innovation and Technology Commission of the Hong Kong Government Special Administrative Region,China.
文摘The rapid advancement of information technology has heightened interest in complementary devices and circuits.Conventional p-type semiconductors often lack sufficient electrical performance,thus prompting the search for new materials with high hole mobility and long-term stability.Elemental tellurium(Te),featuring a one-dimensional chiral atomic structure,has emerged as a promising candidate due to its narrow bandgap,high hole mobility,and versatility in industrial applications,particularly in electronics and renewable energy.This review highlights recent progress in Te nanostructures and related devices,focusing on synthesis methods,including vapor deposition and hydrothermal synthesis,which produce Te nanowires,nanorods,and other nanostructures.Critical applications in photodetectors,gas sensors,and energy harvesting devices are discussed,with a special emphasis on their role within the internet of things(IoT)framework,a rapidly growing field that is reshaping our technological landscape.The prospects and potential applications of Te-based technologies are also highlighted.
基金This work is supported by the National Natural Science Foundation of China(No 52173192 and No 61975241)the Huxiang Youth Talent Program of Hunan Province(2020RC3010)+3 种基金the Science and Technology Innovation Program of Hunan Province(2020RC4004)the Special Funding for the Construction of Innovative Provinces in Hunan Province(2020GK2024)the National Key Research and Development Program of China(2017YFA0206600)P.X.also thanks a fellowship award from the Research Grants Council of the Hong Kong Special Administrative Region,China(CityU RFS2021-1S04).
文摘The emergence of light-tunable synaptic transistors provides opportunities to break through the von Neumann bottleneck and enable neuromorphic computing.Herein,a multifunctional synaptic transistor is constructed by using 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8-BTBT)and indium gallium arsenide(InGaAs)nanowires(NWs)hybrid heterojunction thin film as the active layer.Under illumination,the Type-I C8-BTBT/InGaAs NWs heterojunction would make the dissociated photogenerated excitons more difficult to recombine.The persistent photoconductivity caused by charge trapping can then be used to mimic photosynaptic behaviors,including excitatory postsynaptic current,long/short-term memory and Pavlovian learning.Furthermore,a high classification accuracy of 89.72%can be achieved through the single-layer-perceptron hardware-based neural network built from C8-BTBT/InGaAs NWs synaptic transistors.Thus,this work could provide new insights into the fabrication of high-performance optoelectronic synaptic devices.
基金This work was financially supported by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shen-zhen Park Project(No.HZQB-KCZYB-2020030)the RGC Gen-eral Research Fund(No.AoE/M-402/20,CityU 11209918)+1 种基金the RGC Theme-based Research Scheme(No.T13-402/17-N)the Ma-jor Program of Changsha Science and Technology Project(No.kh2003023).
文摘Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of these properties.Here,a self-assembling nacre-like polymer composite is designed to achieve ex-tremely tough with increasing strength.This special design significantly improved polymer’s mechanical properties,including an ultra-high fracture strain of 1180%,a tensile strength of 55.4 MPa and a toughness of 506.9 MJ/m^(3),which far exceed the highest values previously reported for polymer composites.This ex-cellent combination of properties can be attributed to a novel toughening mechanism,achieved by the synergy of the domain-limiting effect of metallic glass fragments with the strain-gradient-induced orien-tation and crystallisation within the polymer during stretching.Our approach opens a promising avenue for designing robust polymer materials in armour and aerospace engineering for a range of innovative applications.
基金supported by General Research Grant(Project No.11212021,No.11210822)Early Career Scheme(Project No.CityU 21210619)from the Research Grants Council of the Hong Kong Special Administrative Regionthe Innovation and Technology Fund(ITS/065/20,GHP/096/19SZ)from the Innovation and Technology Commission of the Hong Kong Special Administrative Region.
文摘Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.
基金National Natural Science Foundation of China,Grant/Award Number:21872109Fundamental Research Funds for the Central Universities,Grant/Award Numbers:D5000210829,D5000210601Environment and Conservation Fund of Hong Kong SAR,China,Grant/Award Number:ECF 2020-13。
文摘Developing new methodologies to produce clean and renewable energy resources is pivotal for carbon-neutral initiatives.Hydrogen(H2)is considered as an ideal energy resource due to its nontoxic,pollution-free,high utilization rate,and high calorific combustion value.Electrolysis of water driven by the electricity generated from renewable and clean energy sources(e.g.,solar energy,wind energy)to produce hydrogen attracts great efforts for hydrogen production with high purity.Recently,the breakthrough of the catalyst activity limit for the hydrogen evolution reaction(HER)catalysts has received extensive attention.Comparatively,fewer reviews have focused on the long-term stability of HER catalysts,which is indeed decisive for large-scale electrolytic industrialization.Therefore,a systematic summary concentrated on the durability of HER electrocatalysts would provide a fundamental understanding of the electrocatalytic performance for practical applications and offer new opportunities for the rational design of the highly performed HER electrocatalysts.This review summarizes the research progress toward the HER stability of precious metals,transition metals,and metal-free electrocatalysts in the past few years.It discusses the challenges in the stability of HER electrocatalysts and the future perspectives.We anticipate that it would provide a valuable basis for designing robust HER electrocatalysts.
基金supported by the Early Career Scheme of the Research Grants Council of Hong Kong SARChina(City U 139413)+4 种基金the National Natural Science Foundation of China(51202205 and 61504151)the State Key Laboratory of Multiphase Complex Systems(MPCS-2014-C-01 and MPCS-2015-A-04)the Science Technology and Innovation Committee of Shenzhen Municipality(JCYJ20140419115507588)a Grant from the Shenzhen Research InstituteCity University of Hong Kong
文摘To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption, simplification of device fabrication as well as optimization of device structure and geometry, are required. The usage of 1D nanomaterials is attractive due to the outstanding light coupling effect, the ease of fabrication, and integration with one-dimensional(1-D) semiconductor materials. The light absorption efficiency can be enhanced significantly, and the corresponding light-toelectricity conversion efficiency can be as high as their bulk counterparts. Also, the amount of active materials used can be reduced. This review summarizes the recent development of 1-D nanomaterials for photovoltaic applications, including the anti-reflection, the light absorption,the minority diffusion, and the semiconductor junction properties. With solid progress and prospect shown in the past 10 years, 1-D semiconductor nanomaterials are attractive and promising for the realization of high-efficiency and low-cost solar cells.
基金This work was supported by the National Natural Science Foundation of China(Nos.11874351,11874352,51672229,and 61805237)the Hong Kong Scholars Program(No.XJ2019027)+2 种基金the General Research Fund(CityU 11204618)the Theme-based Research(No.T42-103/16-N)of the Research Grants Council of Hong Kong SAR,ChinaCityU SGP-9380076 and the Foshan Innovative and Entrepreneurial Research Team Program(No.2018IT100031).
文摘Hybrid organolead halide perovskites have attracted tremendous attention due to their recent success as high efficiency solar cell materials and their fascinating material properties uniquely suitable for optoelectronic devices. However, the poor ambient and operational stability as well as the concern of lead toxicity greatly hamper their practical utilization. In this work, crystalline, all-inorganic and lead-free Cs_(3)Sb_(2)I_(9) perovskite microplates are successfully synthesized by a two-step chemical vapor deposition method. As compared with other typical lead-free perovskite materials, the Cs_(3)Sb_(2)I_(9) microplates demonstrate excellent optoelectronic properties, including substantial enhancements in the Stokes shift, exciton binding energy and electron-phonon coupling. Simple photoconductive devices fabricated using these microplates exhibit an ultra-fast response with the rise and decay time constants down to 96 and 58 µs, respectively. This respectable photoconductor performance can be regarded as a record among all the lead-free perovskite materials. Importantly, these photodetectors show superior thermal stability in a wide temperature range, capable to function reversibly between 80 and 380 K, indicating their robustness to operate under both low and high temperatures. All these results evidently suggest the technological potential of inorganic lead-free Cs_(3)Sb_(2)I_(9) perovskite microplates for next-generation high-performance optoelectronic devices.
基金supported by MARCO/MSD Focus Center Research Program,Intel Corporation,Lawrence Berkeley National Laboratory,and an Intel Graduate Fellowship(J.C.H.).All fabrication was performed in the UC Berkeley Microlab facility.TEM imaging was performed at the Molecular Foundry,Lawrence Berkeley National Laboratory,which is supported by the Office of Science,Office of Basic Energy Sciences,U.S.Department of Energy,under Contract No.DE-AC02-05CH11231.
文摘InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial InAs nanowires,however,has often relied on the use of Au colloids which is non-CMOS compatible.Here,we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO_(2) substrates.The nanowires show superb electrical properties with field-effect electron mobility~2700 cm^(2)/Vs and ION/IOFF>10^(3).The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance,“printable”transistors,capable of delivering 510 mA ON currents(~400 nanowires).
基金supported by the General Research Fund(CityU 11211317)the Theme-Based Research Scheme(T42-103/16-N)of the Research Grants Council of Hong Kong SAR,China,the National Natural Science Foundation of China(No.51672229)the Science Technology and Innovation Committee of Shenzhen Municipality(No.JCYJ20170818095520778).
文摘Designing highly efficient and low-cost electrocatalysts for oxygen evolution reaction is important for many renewable energy applications.In particular,strain engineering has been demonstrated as a powerful strategy to enhance the electrochemical performance of catalysts;however,the required complex catalyst preparation process restricts the implementation of strain engineering.Herein,we report a simple self-template method to prepare hierarchical porous Co_(3)O_(4)nanowires(PNWs)with tunable compressive strain via thermal-oxidation-transformation of easily prepared oxalic acid-cobalt nitrate(Co(NO_(3))_(2))composite nanowires.Based on the complementary theoretical and experimental studies,the selection of proper solvents in the catalyst preparation is not only vital for the hierarchical structural evolution of Co_(3)O_(4) but also for regulating their compressive surface strain.Because of the rich surface active sites and optimized electronic Co d band centers,the PNWs exhibit the excellent activity and stability for oxygen evolution reaction,delivering a low overpotential of 319 mV at 10 mA·cm^(−2)in 1 M KOH with a mass loading 0.553 mg·cm^(−2),which is even better than the noble metal catalyst of RuO_(2).This work provides a cost-effective example of porous Co_(3)O_(4)nanowire preparation as well as a promising method for modification of surface strain for the enhanced electrochemical performance.
基金We acknowledge the General Research Fund(No.CityU 11306520)the Theme based Research(No.T42-103/16-N)of the Research Grants Council of Hong Kong,Chinathe Foshan Innovative and Entrepreneurial Research Team Program(No.2018IT100031).
文摘Due to the exciting photoelectric properties,better stability,and environmental-friendly nature,all-inorganic halide perovskites(AIHPs),especially the lead-free perovskites,have attracted worldwide attention.However,the film quality of AIHPs fabricated by typical spin-coating and subsequent high-temperature annealing is still not satisfactory,restricting their further development.Herein,we demonstrate a simple low-temperature solution-processed drop-casting method to achieve highly-crystalline cubic CsPbBr_(3)and lead-free layer-structured Cs_(3)Sb_(2)I_(9)microcrystals(MCs).This drop-casting technique not only consumes the less amount of precursor solution but also eliminates the high-temperature annealing as compared with those of spin coating.When these MCs are configured into photodetectors,they exhibit superior device performance,which is in distinct contrast to the one of spin-coated counterparts.Specifically,the responsivity of CsPbBr_(3)MCs is found to be as large as 8,990 mA/W,being 13 times larger than the spin-coated films and even better than many state-of-the-art solution-processed AIHPs devices.This device performance enhancement is attributed to the better film quality and phase purity obtained by the drop-casting method.All these results can evidently fill the“technology gap”for further enhancing the material quality of solution-processed AIHPs and breaking down the barriers that hinder the development of AIHPs based optoelectronic devices.
文摘With luminescent concentrators,the high quantum yield luminescence emitted by embedded chromophores,featuring a broad absorption spectrum,can be well-tuned to match the peak response of integrated photodetectors.This integration can substantially enhance the device photoresponse all the way from deep UV to near-IR.
基金supported by the National Natural Science Foundation of China(51672229)the Environment and Conservation Fund of Hong Kong SAR,China(ECF 2016-85)+1 种基金the General Research Fund of the Research Grants Council of Hong Kong SAR,China(City U 11213115)the Science Technology and Innovation Committee of Shenzhen Municipality(JCYJ20160229165240684)
文摘To date,due to the excellent electrochemical inertness,superb electrical conductivity and good mechanical stability in both aqueous and nonaqueous solutions,platinum(Pt)has been widely employed as counter electrode material in three-electrode setups to perform electroanalytical chemistry.However,recent reports have revealed that the use of Pt based counter electrodes
基金This work was supported by Hong Kong Research Grant Council(RGC)(Nos.CityU 11207416 and CityU 11306520)City University of Hong Kong(No.9667194)the National Natural Science Foundation of China(No.11922215).
文摘Due to the enhanced ambient structural stability and excellent optoelectronic properties, all-inorganic metal halide perovskite nanowires have become one of the most attractive candidates for flexible electronics, photovoltaics and optoelectronics. Their elastic property and mechanical robustness become the key factors for device applications under realistic service conditions with various mechanical loadings. Here, we demonstrate that high tensile elastic strain (∼ 4% to ∼ 5.1%) can be achieved in vapor-liquid-solid-grown single-crystalline CsPbBr_(3) nanowires through in situ scanning electron microscope (SEM) buckling experiments. Such high flexural elasticity can be attributed to the structural defect-scarce, smooth surface, single-crystallinity and nanomechanical size effect of CsPbBr_(3) nanowires. The mechanical reliability of CsPbBr_(3) nanowire-based flexible photodetectors was examined by cyclic bending tests, with no noticeable performance deterioration observed after 5,000 cycles. The above results suggest great application potential for using all-inorganic perovskite nanowires in flexible electronics and energy harvesting systems.
基金financially supported by the Research Fellow Scheme(RFS2021-1S04)the Theme-based Research(T42-103/16-N)of the Research Grants Council of Hong Kong SAR,ChinaFoshan Innovative and Entrepreneurial Research Team Program(2018IT100031)。
文摘Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their photoelectric device performance is still not satisfactory.Herein,we report a facile solution-process method to synthesize the recently most popular lead-free halide double perovskite,MA_(2)Ag Bi Br_(6),and its all-inorganic counterpart,Cs_(2)Ag Bi Br_(6).The obtained MA_(2)Ag Bi Br_(6)and Cs_(2)Ag Bi Br_(6)films exhibit the microplatelet morphology with excellent crystallinity,distinctly contrasting the ones fabricated by the conventional spin-coating method.Once fabricated into simple photodetectors,the Cs_(2)Ag Bi Br_(6)microplatelet devices yield a respectable responsivity of 245 m A W^(-1) that is two orders of magnitude larger than that of the spin-coated films.More importantly,the response speed of the Cs_(2)Ag Bi Br_(6)microplatelets device is as fast as 145μs,which is higher than most of the values reported in the community of halide double perovskites.When subjected to the thermal stability testing,the Cs_(2)Ag Bi Br_(6)microplatelet device can maintain its initial performance after heating to 160℃ and cooling down to room temperature in the ambient environment.All these results suggest that the facile solution-process method is capable of fabricating high-quality lead-free double perovskites,enabling their advanced device applications.
文摘All-inorganic halide perovskites(IHP),CsPbX_(3)(X=Cl,Br,I)exhibiting efficient optical emissions within the spectral range of 410 to 730 nm are potential candidates for many optoelectronic devices.Anion alloying of these IHPs is expected to achieve tunable emission wavelength covering the entire visible spectrum.Here,we developed a two-step chemical vapor deposition(CVD)process for growing quaternary IHP CsPbX_(3)(X=Cl/Br and Br/I)alloys.By exploiting the fast diffusion of halide anions in IHPs,the alloy composition can be precisely controlled by the growth time of the respective layers once the growth of the individual ternary IHP is optimized.Hence complexities in the multi-parameter optimization in the conventional CVD growth of quaternary alloys can be mitigated.Using this process,we synthesized single crystalline,homogeneous and thermally stable CsPbCl3_((1−X))Br_(3x)and CsPbBr3_((1−X))I_(3x)perovskites alloy microplates and demonstrated continuously tunable emission covering the spectrum from 428 to 715 nm by varying the halide compositions in the alloys.These alloy microplates also exhibit room temperature amplified spontaneous emissions(ASE)along with strong photonic discharges from the microplate’s edges and hence are potentially useful as a gain medium as well as optical cavities for emissions with wavelengths covering the visible spectrum.
基金This research was financially supported the National Natural Science Foundation of China(Nos.51672229,61605024,and 61775031)Fundamental Research Funds for the Central Universities(No.ZYGX2018J056)+2 种基金UESTC Foundation for the Academic Newcomers Award,the General Research Fund(CityU No.11275916)the Theme-based Research(No.T42-103/16-N)of the Research Grants Council of Hong Kong,Chinathe Science Technology and Innovation Committee of Shenzhen Municipality(No.Grant JCYJ20170818095520778).
文摘Due to the ultra-thin nature and moderate carrier mobility,semiconducting two-dimensional(2D)materials have attracted extensive attention for next-generation electronics.However,the gate bias stress instability and hysteresis are always observed in these 2D materials-based transistors that significantly degrade their reliability for practical applications.Herein,the origin of gate bias stress instability and hysteresis for chemical vapor deposited monolayer WS2 transistors are investigated carefully.The transistor performance is found to be strongly affected by the gate bias stress time,sweeping rate and range,and temperature.Based on the systematical study and complementary analysis,charge trapping is determined to be the major contribution for these observed phenomena.Importantly,due to these charge trapping effects,the channel current is observed to decrease with time;hence,a rate equation,considering the charge trapping and time decay effect of current,is proposed and developed to model the phenomena with excellent consistency with experimental data.All these results do not only indicate the validity of the charge trapping model,but also confirm the hysteresis being indeed caused by charge trapping.Evidently,this simple model provides a sufficient explanation for the charge trapping induced gate bias stress instability and hysteresis in monolayer WS2 transistors,which can be also applicable to other kinds of transistors.
基金the Research Grants Council of the Hong Kong Special Administrative Region,China(CityU RFS2021-1S04).
文摘Organic-inorganic halide perovskite,as a low-cost,solution-processable material with remarkable optoelectronic properties,is ideal candidate to fabricate high-performance photodetectors and is expected to significantly reduce device costs.Compared to the common Dion-Jacobson and Ruddlesden-Popper two-dimensional(2D)layered hybrid perovskite compounds,the perovskites with alternating cations in the interlayer(ACI)phase show higher crystal symmetry and narrower optical bandgaps,which exhibit great potential for excellent photodetection performance.Herein,we report a high-performance photodetector based on the 2D bilayered hybrid lead halide perovskite single crystal with the ACI phase(GAMA_(2)Pb_(2)I_(7);GA=C(NH_(2))_(3)and MA=CH_(3)NH_(3)).The single-crystal photodetector exhibits high photoresponsivity of 1.56,2.54,and 2.60 A/W for incident light wavelengths of 405,532,and 635 nm under 9.82 nW,respectively,together with the correspondingly high detectivity values of 1.86×10^(12),3.04×10^(12),and 3.11×10^(12)Jones under the same operating conditions.Meanwhile,a high-resolution imaging sensor is built based on the GAMA_(2)Pb_(2)I_(7)single-crystal photodetector,confirming the high stability and photosensitivity of the imaging system.These results show that the 2D hybrid lead halide perovskites with alternating interlayer cations are promising for high-performance visible light photodetectors and imaging systems.
