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
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
无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片...无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片.与传统的溶液旋涂法相比,这种方法得到的Cs_(2)AgBiBr_(6)和MA_(2)Ag Bi Br_(6)微米片具有很好的结晶性.将它们做成光电探测器后,其响应度达到了245 mA W^(-1),比旋涂法制备的器件高出两个量级,且响应时间为145μs.热稳定性研究表明,将Cs_(2)AgBiBr_(6)器件在空气中加热到160℃再回到室温,其光电响应并没有受到影响.这些结果表明,溶液法制备无铅双钙钛矿具有更广阔的应用前景.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
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
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 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)。
文摘无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片.与传统的溶液旋涂法相比,这种方法得到的Cs_(2)AgBiBr_(6)和MA_(2)Ag Bi Br_(6)微米片具有很好的结晶性.将它们做成光电探测器后,其响应度达到了245 mA W^(-1),比旋涂法制备的器件高出两个量级,且响应时间为145μs.热稳定性研究表明,将Cs_(2)AgBiBr_(6)器件在空气中加热到160℃再回到室温,其光电响应并没有受到影响.这些结果表明,溶液法制备无铅双钙钛矿具有更广阔的应用前景.
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.
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.