过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧...过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧化碳排放.另一种替代策略是在贵金属催化剂的辅助下,由氢气和氧气的混合气体在高温下直接合成.但是,氢气和氧气的混合气体在高温下存在爆炸的危险,从而限制了其大规模应用.因此,探索一种低能耗、温和条件下生产过氧化氢具有重要的意义.太阳能驱动光催化生产过氧化氢是解决上述问题的理想途径.通常认为,过氧化氢是由直接双电子还原(E(O2/H2O2)=0.68 V vs.NHE)或间接单电子O2还原(E(O2/•O2−)=-0.33 V vs.NHE)产生的.氧化锌半导体具有很的稳定性好、环保和成本低等优点,因此经常被用于二氧化碳的光催化还原、污水处理和气体传感器等领域.氧化锌的导带电势(ECB=-0.5 V vs.NHE)比氧还原电势更负,意味着它在热力学上满足光催化过氧化氢生产的要求.然而,目前关于氧化锌的光催化生产过氧化氢的研究尚未受到较多的关注.本文采用简单的水热法制备了一维氧化锌纳米棒,在不同温度下热处理后,对其形貌和结构、光学性质和电化学性质进行了表征.同时,系统地研究了以乙醇为牺牲剂光催化生产过氧化氢的性能.结果表明,随着焙烧温度的升高,氧化锌纳米棒内部的氧空位被空气中的氧气重新填充,其催化生成过氧化氢的活性先升高后降低.经300ºC焙烧的氧化锌光催化产过氧化氢的活性最好,为285μmol L-1 h-1.同时,对过氧化氢的生成机理研究结果表明,该过程中为间接单电子O2还原过程.氧气先与一个电子反应生成超氧自由基,再与两个质子和一个电子反应生成过氧化氢分子.综上,本文为氧化锌纳米棒光催化产过氧化氢的机理研究提供了新认识,并提出了一种有前途的过氧化氢生产策略.展开更多
To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods hav...To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods have been experimentally verified to be effective in manifold photocatalytic application over various photocatalysts.Density functional theory(DFT)calculation is a powerful and fundamental tool to pinpoint the intrinsic mechanism of the enhanced photocatalytic activity.And it holds the degree of precision ranging from atoms,molecules to unit cells.Herein,recent DFT calculation research progress of modified s-triazine-based graphitic carbon nitride(g-C3N4)systems as photocatalysts is summarized.To specify,we collected information of doping site,formation energy,geometric,and electronic properties.We also discussed the synergistic effect of work function,Fermi level and band edge position on the built-in electric field,transfer route of photogenerated charge carriers and photocatalytic mechanism(traditional typeⅡor direct Z-scheme heterostructure).Moreover,we analyzed the geometric configuration,band structure,and stability of g-C3N4 nanocluster,nanoribbon,and nanotube.Finally,future perspective in the further theoretical revelation of g-C3N4-based photocatalysts is proposed.展开更多
Smart wearable market is burgeoning,and flexible energy storage is crucial to cope with its development.The commonly-used metal-based current collectors are heavy with limited flexibility.Other carbon-based current co...Smart wearable market is burgeoning,and flexible energy storage is crucial to cope with its development.The commonly-used metal-based current collectors are heavy with limited flexibility.Other carbon-based current collectors are expensive and fragile.Moreover,the poor interface between active material and current collector leads to unsatisfactory stability.Herein,these two issues are attempted to be solved by using cheap and lightweight polyester-based fabrics as well as in-situ growth.A deposited thin layer of nickel on the fabrics not only enhances the conductivity,but also serves as the sacrificial precursor for the growth of active materials.Thus,intimate contact is secured via chemical bonding.The electrode with ternary(metalinorganic-organic)component shows excellent electrochemical performance.Namely,high areal capacity is realized(2.2 C cm^(-2)at 2 mA cm^(-2)),which is far superior to its rigid nickel-foam-based counterpart.Furthermore,an allsolid-state supercapacitor device was assembled.The device provides an areal capacity of 2.03 C cm^(-2)at the current density of 2 mA cm^(-2).It realizes an energy density of 0.45 mWh cm^(-2)when the power density is 1.6 mW cm^(-2).This work offers a feasible and cost-efficient way for fabricating electrode materials with excellent performance for portable supercapacitors.展开更多
Objective:Large volume radiological text data have been accumulated since the incorporation of electronic health record(EHR)systems in clinical practice.We aimed to determine whether deep natural language processing a...Objective:Large volume radiological text data have been accumulated since the incorporation of electronic health record(EHR)systems in clinical practice.We aimed to determine whether deep natural language processing algorithms could aid radiologists in improving thyroid cancer diagnosis.Methods:Sonographic EHR data were obtained from the EHR database.Pathological reports were used as the gold standard for diagnosing thyroid cancer.We developed thyroid cancer diagnosis based on natural language processing(THCaDxNLP)to interpret unstructured sonographic text reports for thyroid cancer diagnosis.We used the area under the receiver operating characteristic curve(AUROC)as the primary metric to measure the performance of the THCaDxNLP.We compared the performance of thyroid ultrasound radiologists aided with THCaDxNLP vs.those without THCaDxNLP using 5 independent test sets.Results:We obtained a total number of 788,129 sonographic radiological reports.The number of thyroid sonographic data points was 132,277,18,400 of which were thyroid cancer patients.Among the 5 test sets,the numbers of patients per set were 439,186,82,343,and 171.THCaDxNLP achieved high performance in identifying thyroid cancer patients(the AUROC ranged from 0.857–0.932).Thyroid ultrasound radiologists aided with THCaDxNLP achieved significantly higher performances than those without THCaDxNLP in terms of accuracy(93.8%vs.87.2%;one-sided t-test,adjusted P=0.003),precision(92.5%vs.86.0%;P=0.018),and F1 metric(94.2%vs.86.4%;P=0.007).Conclusions:THCaDxNLP achieved a high AUROC for the identification of thyroid cancer,and improved the accuracy,sensitivity,and precision of thyroid ultrasound radiologists.This warrants further investigation of THCaDxNLP in prospective clinical trials.展开更多
Recently,multifarious deformation approaches in nature have promoted dynamic manipulation for electromagnetic(EM)waves in metamaterials,and those representative strategies are mainly focused on the modulation of spect...Recently,multifarious deformation approaches in nature have promoted dynamic manipulation for electromagnetic(EM)waves in metamaterials,and those representative strategies are mainly focused on the modulation of spectral parameters.Several works have also achieved tunable phase-gradient meta-devices.Here,to broaden the modulation freedom of mechanical deformation,we initially propose two reconfigurable metamaterials consisting of mirrored S-shaped meta-atoms selectively bonded on biaxially pre-stretched substrates.Planar meta-atoms with spin-insensitive transmittance are buckled into 3D morphologies to break residual symmetries by releasing the stress and to facilitate spin-dependent transmittance under circularly polarized incidence.Owing to the geometric anisotropy of S-shaped meta-atoms along the x and y axes,3D chiral meta-atoms exhibit discriminate circularly cross-polarized transmittance under opposite spins.The underlying physical mechanism reveals that EM resonance originates from the excitation of electric dipoles and magnetic dipoles,and their cross coupling finally triggers the chiral effects of 3D meta-atoms.By introducing the gradient-phase design that keeps unchanged under various strains,two types of meta-atoms with specified orientations are interleaved to design a double-foci metalens,and its 2D-to-3D morphology transformation shortens the focusing length and facilitates the intensity change of two foci.Our approach in designing reconfigurable EM metamaterials with 2D-to-3D buckling transformability can be further extended toward terahertz even optical wavebands,and it may assist with deriving more applicable multi-functionalities in the aspects of imaging,sensing,and holograms.展开更多
Zhang(2021),Luo and Yin(2022)initiated the study of Lagrangian submanifolds satisfying▽*T=0 or▽*T=0 in C^(n) or CP^(n),where T=▽*h and h is the Lagrangian trace-free second fundamental form.They proved several rigi...Zhang(2021),Luo and Yin(2022)initiated the study of Lagrangian submanifolds satisfying▽*T=0 or▽*T=0 in C^(n) or CP^(n),where T=▽*h and h is the Lagrangian trace-free second fundamental form.They proved several rigidity theorems for Lagrangian surfaces satisfying▽*T=0 or▽*▽*T=0 in C2 under proper small energy assumption and gave new characterization of the Whitney spheres in C2.In this paper,the authors extend these results to Lagrangian submanifolds in Cn of dimension n≥3 and to Lagrangian submanifolds in CPn.展开更多
Preparation of efficient photocatalysts with ease of recovery in solar fuel generation is highly desired to achieve carbon neutralization in carbon dioxide(CO_(2))emissions.Inspired from the forest with superior light...Preparation of efficient photocatalysts with ease of recovery in solar fuel generation is highly desired to achieve carbon neutralization in carbon dioxide(CO_(2))emissions.Inspired from the forest with superior light penetration and fast gas transport,a TiO_(2)/g-C_(3)N_(4)composite nanowire arrays(NAs)film with maximized light utilization is devised.It is achieved by in-situ coating a thin layer of g-C_(3)N_(4)(as the leaf)on the vertically-oriented TiO_(2)arrays(as tree trunks)on Ti foil(as soil).Benefiting from the effective charge separation by S-scheme charge transfer,intimate contact by the in-situ growth as well as the ingenious structure,the composite,readily recyclable,displays exciting performance in photocatalytic CO_(2)reduction.It is beyond doubt that the combination of heterojunction construction and“nature-inspired biomimetic photocatalyst”design promises practical applications and industrial use.展开更多
Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow micro...Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.展开更多
In this study,a hierarchical Bi2O3/TiO2 fibrous composite was in-situ fabricated on an electrospun TiO2 nanofiber at ambient temperature.In the Bi2O3/TiO2 composite,S-scheme electron migration occurred between Bi2O3 a...In this study,a hierarchical Bi2O3/TiO2 fibrous composite was in-situ fabricated on an electrospun TiO2 nanofiber at ambient temperature.In the Bi2O3/TiO2 composite,S-scheme electron migration occurred between Bi2O3 and TiO2.In the photocatalytic degradation of phenol under simulated sunlight,the asprepared Bi2O3/TiO2 nanofibers considerably outperformed Bi2O3 nanoparticles and TiO2 nanofibers.This improvement is contributed by maintaining and effectively utilizing the useful carriers and consuming the useless holes and electrons,realized by the S-scheme heterojunction and hierarchical structure.This study also provides an alternative design fashion for photocatalysts.展开更多
Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the gro...Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the growth of nickel-cobalt bisulfide(Ni Co S)nanosheets arrays on carbon cloth(CC)as supercapacitor electrodes is reported,involving deposition of two-dimensional metal-organic framework(MOF)precursors on the CC skeletons,conversion of MOF into nickel-cobalt layered double-hydroxide by ion exchange process and formation of Ni Co S by a sulfidation treatment.The Ni Co S nanosheets with rough surface and porous structures are uniformly anchored on the CC skeletons.The unique architecture endows the composite(Ni Co S/CC)with abundant accessible active sites.Besides,robust electrical/mechanical joint between the nanosheets and the substrates is attained,leading to the improved electrochemical performance.Moreover,an asymmetric supercapacitor device is constructed by using Ni Co S/CC and activated carbon as a positive electrode and a negative electrode,respectively.The optimized device exhibits a high specific capacitance,large energy density and long cycle life.The Ni Co S/CC electrode with intriguing electrochemical properties and mechanical flexibility holds great prospect for next-generation wearable devices.展开更多
Single-atom catalysts have high catalytic activity due to their unique quantum size effects and optimal atom utilization.Herein,visi-ble-light-responsive photocatalysts were designed by coupling CdS with graphene quan...Single-atom catalysts have high catalytic activity due to their unique quantum size effects and optimal atom utilization.Herein,visi-ble-light-responsive photocatalysts were designed by coupling CdS with graphene quantum dots(GQDs)and platinum single atoms(PtSAs).GQDs and PtSAs were successively loaded on ultrathin CdS nanosheets through freeze-drying and in-situ photocatalytic reduction.The synergistic effect between PtSAs and GQDs results in superior photocatalytic activity with a hydrogen production rate of 13488μmol h^(-1)g^(-1)as well as the maximum apparent quantum efficiency(AQE)of 35.5%in lactic acid aqueous solution,which is 62 times higher than that of pristine CdS(213μmol g^(-1)h^(-1)).The energy conversion efficiency is ca.13.05%.As a photosensitizer and an electron reservoir,GQDs can not only extend the light response of CdS to the visible-light region(400-800 nm),but also promotes the separation of photoinduced electron-hole pairs.Meanwhile,PtSAs,with unique electronic and geometric features,can provide more efficient proton reduction sites.This finding provides an effective strategy to remarkably improve the photocatalytic H_(2) production performance.展开更多
A novel cocatalyst,i.e.metallic nickel nanoparticles encapsulated in few-layer graphene(Ni@C),is obtained by carbonization of metal–organic frameworks(MOF)and leaching treatment of hydrochloric acid.It is selected as...A novel cocatalyst,i.e.metallic nickel nanoparticles encapsulated in few-layer graphene(Ni@C),is obtained by carbonization of metal–organic frameworks(MOF)and leaching treatment of hydrochloric acid.It is selected as the cocatalyst for CdS nanosheets,forming CdS-Ni@C nanocomposites.It remarkably improves the photocatalytic activities of CdS nanosheets due to the synergistic effect of Ni nanoparticles and graphene layers.In addition,the Ni nanoparticles encapsulated by graphene layers effectively isolate Ni from the ambient,which avoids contamination and curbs corrosion.The larger work function of Ni@C and outstanding conductivity of graphene promote the electron transfer from CdS to Ni@C,suppressing the recombination of photogenerated carriers and facilitating the separation of photogenerated electronhole pairs.This strategy by adopting this novel cocatalyst provides a new solution to the improvement of the photocatalytic hydrogen production.展开更多
Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry i...Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry is applied and the overall performance of the active material is considerably enhanced.We discover that this treatment triggers the formation of Ni-Co-Cu ternary composite and optimizes the crystal structure of the untreated counterpart.The areal capacitance of the treated sample rockets up to 6.13 F cm^(-2)at 2 m A cm^(-2),almost 13 times higher than the untreated ones.Besides,the resistance is substantially reduced by cyclic voltammetry treatment.Moreover,the Coulombic efficiency and stability are concurrently elevated.The reasons behind this treatment are mulled over and reasonable hypothesis is suggested.This study provides a cheap and effortless way to reform the structures of as-obtained samples as well as vigorously raise the performance of current available materials.展开更多
In recent years,photocatalytic technology,driven by solar energy,has been extensively investigated to ease energy crisis and environmental pollution.Nevertheless,efficiency and stability of photocatalysts are still un...In recent years,photocatalytic technology,driven by solar energy,has been extensively investigated to ease energy crisis and environmental pollution.Nevertheless,efficiency and stability of photocatalysts are still unsatisfactory.To address these issues,design of advanced photocatalysts is important.Cadmium sulphide(CdS)nanomaterials are one of the promising photocatalysts.Among them,hollow-structured CdS,featured with enhanced light absorption ability,large surface area,abundant active sites for redox reactions,and reduced diffusion distance of photogenerated carriers,reveals a broad application prospect.Herein,main synthetic strategies and formation mechanism of hollow CdS photocatalysts are summarized.Besides,we comprehensively discuss the current development of hollow-structured CdS nanomaterials in photocatalytic applications,including H2 production,CO2 reduction and pollutant degradation.Finally,brief conclusions and perspectives on the challenges and future directions for hollow CdS photocatalysts are proposed.展开更多
Sodium-ion batteries are promising candidates for large-scale grid storage systems and other applications.Their foremost advantage derives from superior environmental credentials,enhanced safety as well as lower raw m...Sodium-ion batteries are promising candidates for large-scale grid storage systems and other applications.Their foremost advantage derives from superior environmental credentials,enhanced safety as well as lower raw material costs than lithium-ion batteries.It is still challenging to explore desirable anode material.In this study,FeSe_(2)@CoSe_(2)/FeSe_(2),with a yolk-shell structure was prepared by ion exchange and selenisation.The FeSe_(2)@CoSe_(2)/FeSe_(2)prepared as anode material for sodiumion batteries exhibits excellent rate capability due to the synergistic effect of bimetallic selenides and the interfacial effect of the heterostructure.Moreover,it delivers high performance(510 mAh g^(-1)at 0.2 A g^(-1)),superior rate capa-bility(90%retention at 5 A g^(-1)),and good long-time cycling stability(78%capacity retention after 1800 cycles at a high current density of 2 A g^(-1)).The optimized sodiumion full cell with FeSe_(2)@CoSe_(2)/FeSe_(2)as the anode and Na 3 V 2(PO 4)3 as the cathode still demonstrates excellent performance.Namely,a ca-pacity of 272 mAh g^(-1)(at 1 A g^(-1))within the operating voltage from 1 to 3.8 V can be obtained.This work illustrates the potential of bimetallic selenides with heterostructures for performance enhancement of sodium-ion batteries.展开更多
文摘过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧化碳排放.另一种替代策略是在贵金属催化剂的辅助下,由氢气和氧气的混合气体在高温下直接合成.但是,氢气和氧气的混合气体在高温下存在爆炸的危险,从而限制了其大规模应用.因此,探索一种低能耗、温和条件下生产过氧化氢具有重要的意义.太阳能驱动光催化生产过氧化氢是解决上述问题的理想途径.通常认为,过氧化氢是由直接双电子还原(E(O2/H2O2)=0.68 V vs.NHE)或间接单电子O2还原(E(O2/•O2−)=-0.33 V vs.NHE)产生的.氧化锌半导体具有很的稳定性好、环保和成本低等优点,因此经常被用于二氧化碳的光催化还原、污水处理和气体传感器等领域.氧化锌的导带电势(ECB=-0.5 V vs.NHE)比氧还原电势更负,意味着它在热力学上满足光催化过氧化氢生产的要求.然而,目前关于氧化锌的光催化生产过氧化氢的研究尚未受到较多的关注.本文采用简单的水热法制备了一维氧化锌纳米棒,在不同温度下热处理后,对其形貌和结构、光学性质和电化学性质进行了表征.同时,系统地研究了以乙醇为牺牲剂光催化生产过氧化氢的性能.结果表明,随着焙烧温度的升高,氧化锌纳米棒内部的氧空位被空气中的氧气重新填充,其催化生成过氧化氢的活性先升高后降低.经300ºC焙烧的氧化锌光催化产过氧化氢的活性最好,为285μmol L-1 h-1.同时,对过氧化氢的生成机理研究结果表明,该过程中为间接单电子O2还原过程.氧气先与一个电子反应生成超氧自由基,再与两个质子和一个电子反应生成过氧化氢分子.综上,本文为氧化锌纳米棒光催化产过氧化氢的机理研究提供了新认识,并提出了一种有前途的过氧化氢生产策略.
基金This work was supported by NSFC(U1705251,21573170,21905219,and 21433007)National Postdoctoral Program for Innovative Talents(BX20180231)+2 种基金Fundamental Research Funds for the Central Universities(WUT:2018IVA089)Innovative Research Funds of SKLWUT(2017-ZD-4)Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(JDGD-201704).
文摘To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods have been experimentally verified to be effective in manifold photocatalytic application over various photocatalysts.Density functional theory(DFT)calculation is a powerful and fundamental tool to pinpoint the intrinsic mechanism of the enhanced photocatalytic activity.And it holds the degree of precision ranging from atoms,molecules to unit cells.Herein,recent DFT calculation research progress of modified s-triazine-based graphitic carbon nitride(g-C3N4)systems as photocatalysts is summarized.To specify,we collected information of doping site,formation energy,geometric,and electronic properties.We also discussed the synergistic effect of work function,Fermi level and band edge position on the built-in electric field,transfer route of photogenerated charge carriers and photocatalytic mechanism(traditional typeⅡor direct Z-scheme heterostructure).Moreover,we analyzed the geometric configuration,band structure,and stability of g-C3N4 nanocluster,nanoribbon,and nanotube.Finally,future perspective in the further theoretical revelation of g-C3N4-based photocatalysts is proposed.
基金supported by National Natural Science Foundation of China(21801200 and 22075217)National Key Research and Development Program of China(No.2018YFB1502001)+2 种基金the Innovative Research Funds of Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHD2020-001)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education,Jianghan University(JDGD-202020)the Fundamental Research Funds for Central Universities(2021ⅣA137)。
文摘Smart wearable market is burgeoning,and flexible energy storage is crucial to cope with its development.The commonly-used metal-based current collectors are heavy with limited flexibility.Other carbon-based current collectors are expensive and fragile.Moreover,the poor interface between active material and current collector leads to unsatisfactory stability.Herein,these two issues are attempted to be solved by using cheap and lightweight polyester-based fabrics as well as in-situ growth.A deposited thin layer of nickel on the fabrics not only enhances the conductivity,but also serves as the sacrificial precursor for the growth of active materials.Thus,intimate contact is secured via chemical bonding.The electrode with ternary(metalinorganic-organic)component shows excellent electrochemical performance.Namely,high areal capacity is realized(2.2 C cm^(-2)at 2 mA cm^(-2)),which is far superior to its rigid nickel-foam-based counterpart.Furthermore,an allsolid-state supercapacitor device was assembled.The device provides an areal capacity of 2.03 C cm^(-2)at the current density of 2 mA cm^(-2).It realizes an energy density of 0.45 mWh cm^(-2)when the power density is 1.6 mW cm^(-2).This work offers a feasible and cost-efficient way for fabricating electrode materials with excellent performance for portable supercapacitors.
基金This work was supported by the National Natural Science Foundation of China(Grant No.31801117 to Dr.X.Li and 82073287 to Dr.Zhang)the Program for Changjiang Scholars and Innovative Research Team in University in China(Grant No.IRT_14R40 to Dr.K.Chen)the Chinese National Key Research and Development Project(Grant No.2018YFC1315601).
文摘Objective:Large volume radiological text data have been accumulated since the incorporation of electronic health record(EHR)systems in clinical practice.We aimed to determine whether deep natural language processing algorithms could aid radiologists in improving thyroid cancer diagnosis.Methods:Sonographic EHR data were obtained from the EHR database.Pathological reports were used as the gold standard for diagnosing thyroid cancer.We developed thyroid cancer diagnosis based on natural language processing(THCaDxNLP)to interpret unstructured sonographic text reports for thyroid cancer diagnosis.We used the area under the receiver operating characteristic curve(AUROC)as the primary metric to measure the performance of the THCaDxNLP.We compared the performance of thyroid ultrasound radiologists aided with THCaDxNLP vs.those without THCaDxNLP using 5 independent test sets.Results:We obtained a total number of 788,129 sonographic radiological reports.The number of thyroid sonographic data points was 132,277,18,400 of which were thyroid cancer patients.Among the 5 test sets,the numbers of patients per set were 439,186,82,343,and 171.THCaDxNLP achieved high performance in identifying thyroid cancer patients(the AUROC ranged from 0.857–0.932).Thyroid ultrasound radiologists aided with THCaDxNLP achieved significantly higher performances than those without THCaDxNLP in terms of accuracy(93.8%vs.87.2%;one-sided t-test,adjusted P=0.003),precision(92.5%vs.86.0%;P=0.018),and F1 metric(94.2%vs.86.4%;P=0.007).Conclusions:THCaDxNLP achieved a high AUROC for the identification of thyroid cancer,and improved the accuracy,sensitivity,and precision of thyroid ultrasound radiologists.This warrants further investigation of THCaDxNLP in prospective clinical trials.
基金National Natural Science Foundation of China(52175115)。
文摘Recently,multifarious deformation approaches in nature have promoted dynamic manipulation for electromagnetic(EM)waves in metamaterials,and those representative strategies are mainly focused on the modulation of spectral parameters.Several works have also achieved tunable phase-gradient meta-devices.Here,to broaden the modulation freedom of mechanical deformation,we initially propose two reconfigurable metamaterials consisting of mirrored S-shaped meta-atoms selectively bonded on biaxially pre-stretched substrates.Planar meta-atoms with spin-insensitive transmittance are buckled into 3D morphologies to break residual symmetries by releasing the stress and to facilitate spin-dependent transmittance under circularly polarized incidence.Owing to the geometric anisotropy of S-shaped meta-atoms along the x and y axes,3D chiral meta-atoms exhibit discriminate circularly cross-polarized transmittance under opposite spins.The underlying physical mechanism reveals that EM resonance originates from the excitation of electric dipoles and magnetic dipoles,and their cross coupling finally triggers the chiral effects of 3D meta-atoms.By introducing the gradient-phase design that keeps unchanged under various strains,two types of meta-atoms with specified orientations are interleaved to design a double-foci metalens,and its 2D-to-3D morphology transformation shortens the focusing length and facilitates the intensity change of two foci.Our approach in designing reconfigurable EM metamaterials with 2D-to-3D buckling transformability can be further extended toward terahertz even optical wavebands,and it may assist with deriving more applicable multi-functionalities in the aspects of imaging,sensing,and holograms.
基金supported by the National Natural Science Foundation of China(No.12271069)the Natural Science Foundation of Chongqing(No.cstc2021jcyj-msxm X0443)+1 种基金the Chongqing“Zhitongche”foundation for doctors(No.CSTB2022BSXM-JCX0101)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJQN202201138)。
文摘Zhang(2021),Luo and Yin(2022)initiated the study of Lagrangian submanifolds satisfying▽*T=0 or▽*T=0 in C^(n) or CP^(n),where T=▽*h and h is the Lagrangian trace-free second fundamental form.They proved several rigidity theorems for Lagrangian surfaces satisfying▽*T=0 or▽*▽*T=0 in C2 under proper small energy assumption and gave new characterization of the Whitney spheres in C2.In this paper,the authors extend these results to Lagrangian submanifolds in Cn of dimension n≥3 and to Lagrangian submanifolds in CPn.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.51932007,51872220,51961135303,21871217,52073223,52063028,U1905215 and U1705251)。
文摘Preparation of efficient photocatalysts with ease of recovery in solar fuel generation is highly desired to achieve carbon neutralization in carbon dioxide(CO_(2))emissions.Inspired from the forest with superior light penetration and fast gas transport,a TiO_(2)/g-C_(3)N_(4)composite nanowire arrays(NAs)film with maximized light utilization is devised.It is achieved by in-situ coating a thin layer of g-C_(3)N_(4)(as the leaf)on the vertically-oriented TiO_(2)arrays(as tree trunks)on Ti foil(as soil).Benefiting from the effective charge separation by S-scheme charge transfer,intimate contact by the in-situ growth as well as the ingenious structure,the composite,readily recyclable,displays exciting performance in photocatalytic CO_(2)reduction.It is beyond doubt that the combination of heterojunction construction and“nature-inspired biomimetic photocatalyst”design promises practical applications and industrial use.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51872220,51932007,51961135303,21871217,U1905215 and U1705251)the National Key Research and Development Program of China(No.2018YFB1502001)the Fundamental Research Funds for the Central Universities(No.WUT:2019IVB050)。
文摘Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.
基金financially supported by the National Natural Science Foundation of China(Nos.51872220 and 21871030)the Natural Science Foundation of Hunan Province of China(Nos.2018JJ2456 and 2018JJ2457)the Scientific Research Fund of Hunan Provincial Education Department of China(No.18A370)。
文摘In this study,a hierarchical Bi2O3/TiO2 fibrous composite was in-situ fabricated on an electrospun TiO2 nanofiber at ambient temperature.In the Bi2O3/TiO2 composite,S-scheme electron migration occurred between Bi2O3 and TiO2.In the photocatalytic degradation of phenol under simulated sunlight,the asprepared Bi2O3/TiO2 nanofibers considerably outperformed Bi2O3 nanoparticles and TiO2 nanofibers.This improvement is contributed by maintaining and effectively utilizing the useful carriers and consuming the useless holes and electrons,realized by the S-scheme heterojunction and hierarchical structure.This study also provides an alternative design fashion for photocatalysts.
基金supported by NSFC(21801200,U1905215,U1705251 and 51872220)Innovative Research Funds of SKLWUT(2017-ZD-4)Fundamental Research Funds for the Central Universities(WUT:2019IVB050)。
文摘Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the growth of nickel-cobalt bisulfide(Ni Co S)nanosheets arrays on carbon cloth(CC)as supercapacitor electrodes is reported,involving deposition of two-dimensional metal-organic framework(MOF)precursors on the CC skeletons,conversion of MOF into nickel-cobalt layered double-hydroxide by ion exchange process and formation of Ni Co S by a sulfidation treatment.The Ni Co S nanosheets with rough surface and porous structures are uniformly anchored on the CC skeletons.The unique architecture endows the composite(Ni Co S/CC)with abundant accessible active sites.Besides,robust electrical/mechanical joint between the nanosheets and the substrates is attained,leading to the improved electrochemical performance.Moreover,an asymmetric supercapacitor device is constructed by using Ni Co S/CC and activated carbon as a positive electrode and a negative electrode,respectively.The optimized device exhibits a high specific capacitance,large energy density and long cycle life.The Ni Co S/CC electrode with intriguing electrochemical properties and mechanical flexibility holds great prospect for next-generation wearable devices.
基金supported by the National Key Research and Development Program of China(2018YFB1502001)National Natural Science Foundation of China(NSFC)(Nos.51872220,51961135303,51932007,U1905215,21871217 and 52073223)Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah(No.RG-72-130-42)。
文摘Single-atom catalysts have high catalytic activity due to their unique quantum size effects and optimal atom utilization.Herein,visi-ble-light-responsive photocatalysts were designed by coupling CdS with graphene quantum dots(GQDs)and platinum single atoms(PtSAs).GQDs and PtSAs were successively loaded on ultrathin CdS nanosheets through freeze-drying and in-situ photocatalytic reduction.The synergistic effect between PtSAs and GQDs results in superior photocatalytic activity with a hydrogen production rate of 13488μmol h^(-1)g^(-1)as well as the maximum apparent quantum efficiency(AQE)of 35.5%in lactic acid aqueous solution,which is 62 times higher than that of pristine CdS(213μmol g^(-1)h^(-1)).The energy conversion efficiency is ca.13.05%.As a photosensitizer and an electron reservoir,GQDs can not only extend the light response of CdS to the visible-light region(400-800 nm),but also promotes the separation of photoinduced electron-hole pairs.Meanwhile,PtSAs,with unique electronic and geometric features,can provide more efficient proton reduction sites.This finding provides an effective strategy to remarkably improve the photocatalytic H_(2) production performance.
基金Financially supported by the National Key Research and Development Program of China(No.2018YFB1502001)the National Natural Science Foundation of China(Nos.51872220,21871217,51961135303,51932007,U1905215 and U1705251)。
文摘A novel cocatalyst,i.e.metallic nickel nanoparticles encapsulated in few-layer graphene(Ni@C),is obtained by carbonization of metal–organic frameworks(MOF)and leaching treatment of hydrochloric acid.It is selected as the cocatalyst for CdS nanosheets,forming CdS-Ni@C nanocomposites.It remarkably improves the photocatalytic activities of CdS nanosheets due to the synergistic effect of Ni nanoparticles and graphene layers.In addition,the Ni nanoparticles encapsulated by graphene layers effectively isolate Ni from the ambient,which avoids contamination and curbs corrosion.The larger work function of Ni@C and outstanding conductivity of graphene promote the electron transfer from CdS to Ni@C,suppressing the recombination of photogenerated carriers and facilitating the separation of photogenerated electronhole pairs.This strategy by adopting this novel cocatalyst provides a new solution to the improvement of the photocatalytic hydrogen production.
基金the National Natural Science Foundation of China(Nos.21801200,21871217,U1905215 and 51872220)the Fundamental Research Funds for the Central Universities(Nos.WUT:2019IVB050,182459018 and 195201044)the Project of Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,Saudi Arabia(No.FP-179-42)。
文摘Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry is applied and the overall performance of the active material is considerably enhanced.We discover that this treatment triggers the formation of Ni-Co-Cu ternary composite and optimizes the crystal structure of the untreated counterpart.The areal capacitance of the treated sample rockets up to 6.13 F cm^(-2)at 2 m A cm^(-2),almost 13 times higher than the untreated ones.Besides,the resistance is substantially reduced by cyclic voltammetry treatment.Moreover,the Coulombic efficiency and stability are concurrently elevated.The reasons behind this treatment are mulled over and reasonable hypothesis is suggested.This study provides a cheap and effortless way to reform the structures of as-obtained samples as well as vigorously raise the performance of current available materials.
基金supported by the National Key Research and Development Program of China(2018YFB1502001)the National Natural Science Foundation of China(51932007,51961135303,U1905215,21871217,and U1705251)+1 种基金National Innovation and Entrepreneurship Training Program for College Students(No.201910497026)the Innovative Research Funds of Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHD2020-001).
文摘In recent years,photocatalytic technology,driven by solar energy,has been extensively investigated to ease energy crisis and environmental pollution.Nevertheless,efficiency and stability of photocatalysts are still unsatisfactory.To address these issues,design of advanced photocatalysts is important.Cadmium sulphide(CdS)nanomaterials are one of the promising photocatalysts.Among them,hollow-structured CdS,featured with enhanced light absorption ability,large surface area,abundant active sites for redox reactions,and reduced diffusion distance of photogenerated carriers,reveals a broad application prospect.Herein,main synthetic strategies and formation mechanism of hollow CdS photocatalysts are summarized.Besides,we comprehensively discuss the current development of hollow-structured CdS nanomaterials in photocatalytic applications,including H2 production,CO2 reduction and pollutant degradation.Finally,brief conclusions and perspectives on the challenges and future directions for hollow CdS photocatalysts are proposed.
基金supported by the National Natural Science Foundation of China(Nos.21801200 and 22075217)the Open Project of Hunan Key Laboratory of Applied Environmental Photocatalysis(No.2114504)the Natural Science Foundation of Hubei Province of China(No.2022CFA001).
文摘Sodium-ion batteries are promising candidates for large-scale grid storage systems and other applications.Their foremost advantage derives from superior environmental credentials,enhanced safety as well as lower raw material costs than lithium-ion batteries.It is still challenging to explore desirable anode material.In this study,FeSe_(2)@CoSe_(2)/FeSe_(2),with a yolk-shell structure was prepared by ion exchange and selenisation.The FeSe_(2)@CoSe_(2)/FeSe_(2)prepared as anode material for sodiumion batteries exhibits excellent rate capability due to the synergistic effect of bimetallic selenides and the interfacial effect of the heterostructure.Moreover,it delivers high performance(510 mAh g^(-1)at 0.2 A g^(-1)),superior rate capa-bility(90%retention at 5 A g^(-1)),and good long-time cycling stability(78%capacity retention after 1800 cycles at a high current density of 2 A g^(-1)).The optimized sodiumion full cell with FeSe_(2)@CoSe_(2)/FeSe_(2)as the anode and Na 3 V 2(PO 4)3 as the cathode still demonstrates excellent performance.Namely,a ca-pacity of 272 mAh g^(-1)(at 1 A g^(-1))within the operating voltage from 1 to 3.8 V can be obtained.This work illustrates the potential of bimetallic selenides with heterostructures for performance enhancement of sodium-ion batteries.
