Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable e...Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable energy consumption.Herein,a simple three-step strategy is reported to construct cobalt-iron nitride/alloy nanosheets on nickel foam(CoFe-NA/NF)as a bifunctional catalyst for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The electrocatalyst with optimized composition(CoFe-NA2/NF)can achieve ultralow overpotentials of 73 mV and 250 mV for HER and OER,respectively,at a current density of 10 mA cm^(-2) in 1 M KOH.Notably,the electrolyzer based on this electrocatalyst is able to boost the overall water splitting with a cell voltage of 1.564 V to deliver 10 mA cm^(-2) for at least 50 h without obvious performance decay.Furthermore,our experiment and theoretical calculation demonstrate that the combination of cobalt-iron nitride and alloy can have low hydrogen adsorption energy and facilitate water dissociation during HER.In addition,the surface reconstruction introduces metal oxyhydroxides to optimize the OER process.Our work may pave a new pathway to design bifunctional catalysts for overall water splitting.展开更多
The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of perovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an underst...The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of perovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understanding of structure-performance relationships is of vital importance for developing high-performance perovskite devices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight secondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA_(2)Cs_(n-1)Pb_(n)(Br_(0.3)I_(0.7))_(3n+1)(DPPA^(+):3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n domains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4%.The optimized device had a maximum luminance of 623 cd/m^(2) with a peak EQE of 9.7%.展开更多
碱性水电解(AWE)作为一种具有工业应用前景的绿色制氢方法,能够用来改善能源短缺和环境污染问题.然而,由于电极材料昂贵且效率低下,这种方法生产氢气的效率比较低.本文采用块状AlCoCrFeNi高熵合金作为碱性电解水的有效电极.研究发现通...碱性水电解(AWE)作为一种具有工业应用前景的绿色制氢方法,能够用来改善能源短缺和环境污染问题.然而,由于电极材料昂贵且效率低下,这种方法生产氢气的效率比较低.本文采用块状AlCoCrFeNi高熵合金作为碱性电解水的有效电极.研究发现通过快速阳极氧化(5 min)处理的高熵合金可以同时对析氢和析氧反应(HER和OER)具有超高的催化活性,只需要880和845 m V的过电位就可以达到-500 mA cm-2(HER)和500 mA cm-2(OER)的电流密度.特别地,该催化剂只需要3.00 V就可以达到500 mA cm-2的全解水电流密度,并且在此电流密度下表现出超过100小时的出色稳定性.我们的研究表明,阳极氧化的块体AlCoCrFeNi高熵合金作为高效催化剂在工业水电解制氢中具有广阔的应用前景,有望用于缓解环境问题和能源危机.展开更多
Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial appl...Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial application on a large scale is still a huge challenge.Recently,high entropy alloy(HEA)has acquired extensive attention,which may provide answers to the current dilemma.Here,we report bulk Fe_(50)Mn_(30)Co_(10)Cr_(10),which is prepared by 3D printing on a large scale,as electrocatalyst for OER with high catalytic performance.Especially,an easy approach,corrosion engineering,is adopted for the first time to build an active layer of honeycomb nanostructures on its surface,leading to ultrahigh OER performance with an overpotential of 247 mV to achieve a current density of 10 mA cm^(-2),a low Tafel slope of 63 mV dec^(-1),and excellent stability up to 60 h at 100 mA cm^(-2)in 1 M KOH.The excellent catalytic activity mainly originates from:(1)the binder-free self-supported honeycomb nanostructures and multi-component hydroxides,which improve intrinsic catalytic activity,provide rich active sites,and reduce interfacial resistance;and(2)the diverse valence states for multiple active sites to enhance the OER kinetics.Our findings show that corrosion engineering is a novel strategy to improve the bulk HEA catalytic performance.We expect that this work would open up a new avenue to fabricate large-scale HEA electrocatalysts by 3D printing and corrosion engineering for industrial applications.展开更多
The most widely used method of identification of microbial morphology and structure is microscopy,but it can be difficult to distinguish between pathogens with a similar appearance.Existing fluorescent staining method...The most widely used method of identification of microbial morphology and structure is microscopy,but it can be difficult to distinguish between pathogens with a similar appearance.Existing fluorescent staining methods require a combination of a variety of fluorescent materials to meet this demand.In this study,unique concentration-dependent fluorescent carbon dots(CDs)were synthesized for the identification and quantification of pathogens.The emission wavelength of the CDs could be tuned spanning the full visible region by virtue of aggregation-induced narrowing of bandgaps.This tunable emission wavelength of the specific concentration response to diverse microbes can be used to distinguish microorganisms with a similar appearance,even in a same genus.A hyperspectral microscopy system was demonstrated to distinguish Aspergillus flavus and A.fumigatus based on the results above.The identification accuracy of the two similar-looking pathogens can be close to 100%,and the relative proportions and spatial distributions can also be profiled from the mixture of the pathogens.This technique can provide a solution to the fast detection of microorganisms and is potentially applicable to a wide range of problems in areas such as healthcare,food preparation,biotechnology,and health emergency.展开更多
Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in t...Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in the mechanism investigation,material chemistry,and device engineering of QLEDs,the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices.Here,we report a comprehensive study on the characterizations of QLEDs using various methods.We show that the emission non-uniformity across the active area,nonLambertian angular distributions of EL intensity,and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency.Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves.Finally,we suggest a set of recommended practices and a checklist for device characterizations,aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.展开更多
基金supported by the Science and Technology Development Fund from Macao SAR(FDCT)(0102/2019/A2,0035/2019/AGJ,0154/2019/A3,0081/2019/AMJ,and 0033/2019/AMJ)Multi-Year Research Grants(MYRG2017-00027-FST and MYRG2018-00003-IAPME)from Research&Development Office at University of Macao。
文摘Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable energy consumption.Herein,a simple three-step strategy is reported to construct cobalt-iron nitride/alloy nanosheets on nickel foam(CoFe-NA/NF)as a bifunctional catalyst for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The electrocatalyst with optimized composition(CoFe-NA2/NF)can achieve ultralow overpotentials of 73 mV and 250 mV for HER and OER,respectively,at a current density of 10 mA cm^(-2) in 1 M KOH.Notably,the electrolyzer based on this electrocatalyst is able to boost the overall water splitting with a cell voltage of 1.564 V to deliver 10 mA cm^(-2) for at least 50 h without obvious performance decay.Furthermore,our experiment and theoretical calculation demonstrate that the combination of cobalt-iron nitride and alloy can have low hydrogen adsorption energy and facilitate water dissociation during HER.In addition,the surface reconstruction introduces metal oxyhydroxides to optimize the OER process.Our work may pave a new pathway to design bifunctional catalysts for overall water splitting.
基金supported by the National Natural Science Foundation of China(61735004).
文摘The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of perovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understanding of structure-performance relationships is of vital importance for developing high-performance perovskite devices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight secondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA_(2)Cs_(n-1)Pb_(n)(Br_(0.3)I_(0.7))_(3n+1)(DPPA^(+):3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n domains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4%.The optimized device had a maximum luminance of 623 cd/m^(2) with a peak EQE of 9.7%.
基金supported by the Multi-Year Research Grants(MYRG2020-00207-IAPME)from the University of Macaothe Science and Technology Development Fund from Macao SAR(FDCT)(0125/2018/A3,0081/2019/AMJ,0033/2019/AMJ,0102/2019/A2,and 0154/2019/A3)+1 种基金the Nature Science Foundation of Shandong Province(ZR2020ZD04)Hunan Science Fund for Distinguished Young Scholars(2020JJ2046).
文摘碱性水电解(AWE)作为一种具有工业应用前景的绿色制氢方法,能够用来改善能源短缺和环境污染问题.然而,由于电极材料昂贵且效率低下,这种方法生产氢气的效率比较低.本文采用块状AlCoCrFeNi高熵合金作为碱性电解水的有效电极.研究发现通过快速阳极氧化(5 min)处理的高熵合金可以同时对析氢和析氧反应(HER和OER)具有超高的催化活性,只需要880和845 m V的过电位就可以达到-500 mA cm-2(HER)和500 mA cm-2(OER)的电流密度.特别地,该催化剂只需要3.00 V就可以达到500 mA cm-2的全解水电流密度,并且在此电流密度下表现出超过100小时的出色稳定性.我们的研究表明,阳极氧化的块体AlCoCrFeNi高熵合金作为高效催化剂在工业水电解制氢中具有广阔的应用前景,有望用于缓解环境问题和能源危机.
基金supported by the Science and Technology Development Fund from Macao SAR(FDCT)(Nos.0102/2019/A2,0035/2019/AGJ,0154/2019/A3,0081/2019/AMJ,0033/2019/AMJ and 0125/2018/A3)Multi-Year Research Grants(MYRG2018-00003IAPME)from the University of Macao。
文摘Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial application on a large scale is still a huge challenge.Recently,high entropy alloy(HEA)has acquired extensive attention,which may provide answers to the current dilemma.Here,we report bulk Fe_(50)Mn_(30)Co_(10)Cr_(10),which is prepared by 3D printing on a large scale,as electrocatalyst for OER with high catalytic performance.Especially,an easy approach,corrosion engineering,is adopted for the first time to build an active layer of honeycomb nanostructures on its surface,leading to ultrahigh OER performance with an overpotential of 247 mV to achieve a current density of 10 mA cm^(-2),a low Tafel slope of 63 mV dec^(-1),and excellent stability up to 60 h at 100 mA cm^(-2)in 1 M KOH.The excellent catalytic activity mainly originates from:(1)the binder-free self-supported honeycomb nanostructures and multi-component hydroxides,which improve intrinsic catalytic activity,provide rich active sites,and reduce interfacial resistance;and(2)the diverse valence states for multiple active sites to enhance the OER kinetics.Our findings show that corrosion engineering is a novel strategy to improve the bulk HEA catalytic performance.We expect that this work would open up a new avenue to fabricate large-scale HEA electrocatalysts by 3D printing and corrosion engineering for industrial applications.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61935010,61975069,21905253,and 51973200)the China Postdoctoral Science Foundation(Nos.2018M640681 and 2019T120632)+5 种基金the Natural Science Foundation of Henan(No.202300410372)Key-Area Research and Development Program of Guangdong Province(No.2020B090922006)Guangdong Project of Science and Technology Grants(No.2018B030323017)Guangzhou science and technology project(Nos.201903010042 and 201904010294)Youth project of science and technology research program of Chongqing Education Commission of China(No.KJQN202001322)the Science and Technology Development Fund from Macao SAR(File Nos.0125/2018/A3 and 0071/2019/AMJ).
文摘The most widely used method of identification of microbial morphology and structure is microscopy,but it can be difficult to distinguish between pathogens with a similar appearance.Existing fluorescent staining methods require a combination of a variety of fluorescent materials to meet this demand.In this study,unique concentration-dependent fluorescent carbon dots(CDs)were synthesized for the identification and quantification of pathogens.The emission wavelength of the CDs could be tuned spanning the full visible region by virtue of aggregation-induced narrowing of bandgaps.This tunable emission wavelength of the specific concentration response to diverse microbes can be used to distinguish microorganisms with a similar appearance,even in a same genus.A hyperspectral microscopy system was demonstrated to distinguish Aspergillus flavus and A.fumigatus based on the results above.The identification accuracy of the two similar-looking pathogens can be close to 100%,and the relative proportions and spatial distributions can also be profiled from the mixture of the pathogens.This technique can provide a solution to the fast detection of microorganisms and is potentially applicable to a wide range of problems in areas such as healthcare,food preparation,biotechnology,and health emergency.
基金supported by National Natural Science Foundation of China (21975220,91833303,21922305,21873080,21703202,62122034,and 61875082)Key Research and Development Project of Zhejiang Province (2020C01001)+1 种基金National Key Research and Development Program of China (2021YFB3601700)China Postdoctoral Science Foundation (2021M702800).
文摘Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in the mechanism investigation,material chemistry,and device engineering of QLEDs,the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices.Here,we report a comprehensive study on the characterizations of QLEDs using various methods.We show that the emission non-uniformity across the active area,nonLambertian angular distributions of EL intensity,and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency.Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves.Finally,we suggest a set of recommended practices and a checklist for device characterizations,aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.