Broadband photodetectors with self-driven functions have attracted intensive scientific interest due to their low energy consumption and high optical gain.However,high-performance broadband self-driven photodetectors ...Broadband photodetectors with self-driven functions have attracted intensive scientific interest due to their low energy consumption and high optical gain.However,high-performance broadband self-driven photodetectors are still a significant challenge due to the complex fabrication processes,environmental toxicity,high production costs of traditional 3D semiconductor materials and sharply raised contact resistance,severe interfacial recombination of 2D materials and 2D/3D mixed dimension heterojunction.Here,1D p-Te/2D n-Bi_(2)Te_(3) heterojunctions are constructed by the simple and low-cost hydrothermal method.1D p-Te/2D n-Bi_(2)Te_(3) devices are applied in photoelectrochemical(PEC)photodetectors,with their high performance attributed to the good interfacial contacts reducing interface recombination.The device demonstrated a broad wavelength range(365–850 nm)with an Iph/Idark as high as 377.45.The R_(i),D^(*),and external quantum efficiency(EQE)values of the device were as high as 12.07 mA/W,5.87×10^(10) Jones,and 41.05%,respectively,which were significantly better than the performance of the prepared Bi_(2)Te_(3) and Te devices.A comparison of the freshly fabricated device and the device after 30 days showed that 1D p-Te/2D n-Bi_(2)Te_(3) had excellent stability with only 18.08%decay of photocurrent.It is anticipated that this work will provide new emerging material for future design and preparation of a high-performance self-driven broadband photodetector.展开更多
Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To...Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To date,most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis.However,a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered.Here,a series of TiO_(2-X)mesoporous spheres(MS)with different oxygen vacancy concentrations for photocatalytic applications were prepared by hightemperature chemical reduction.The link between oxygen vacancy concentration and photocatalytic performance was successfully established.The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration,which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis.As the reduction temperature rises to 300℃,carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs,thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants,as demonstrated by a hydrogen evolution rate of 523.7μmol g^(-1)h^(-1)and a ninefold higher RhB photodegradation rate compared to TiO_(2)MS.The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.展开更多
Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled che...Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions,drug delivery,and functional material synthesis.Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control.Specifically,Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration.Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions,where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact.We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields,which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement.Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale,which could shed light on new possibilities in key fields of controlled chemistry reaction,medicine synthesis,and energy generation.展开更多
Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices...Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing applications.Here we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon resonance.In this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal cavity.The quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar substrate.Such an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level concentrations.Therefore,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing technologies.At the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.展开更多
Templated growth is an important synthetic strategy for the construction of complex multicomponent nanostructures [1-3]. The commonly-used templates can be made from either “hard” materials [4-7](e.g., silica) or &q...Templated growth is an important synthetic strategy for the construction of complex multicomponent nanostructures [1-3]. The commonly-used templates can be made from either “hard” materials [4-7](e.g., silica) or "soft" materials (e.g., micelles [8], polymers [9], supramolecules [10], etc.). Hard templates typically allow for good crystallinity of the final nanostructures and better preservation of the geometric feature of original templates [7,11], while soft templates are relatively easy to prepare and remove during the synthesis [12,13]. Recently, polymer- tethered inorganic nanoparticle (NP) assemblies (e.g., one-dimensional chains [14-17], two-dimensional sheets [18], and three-dimensional vesicles [19]) have attracted reasonable attention for their potential applications in diverse fields, such as bio-imaging and drug delivery [16] and surfece enhanced Raman scattering (SERS)[20]. Furthermore, these polymer-inorganic NP assemblies can serve as a new class of mixed soft-hard colloidal template for the fabrication of unconventional nanostructures. For instance, Nie and co-authors [21] firstly synthesized a variety of coaxial-like and Saturn-like multicomponent nanostructures by selective deposition of metals (e.g., Pd, Pt, Ag, Ni, etc.) or metal oxides (e.g., CeO2 and Cu2O) on seed Au NPs organized in polymer- Au NP assemblies, followed by dissociation of the assemblies. Nevertheless, there remains a challenge to precisely control the selective depos让ion of growth materials on the mixed soft-hard templates.展开更多
Noble metal alloys are one of the most commonly used heterogeneous catalysts.During many reactions,the surface composition and oxidation states of the noble metal alloy particles have been reported to be dynamic.This ...Noble metal alloys are one of the most commonly used heterogeneous catalysts.During many reactions,the surface composition and oxidation states of the noble metal alloy particles have been reported to be dynamic.This paper describes a density functional theory study to explore the initial oxidation stages of the Ptbased surfaces,which are widely-used catalysts in various clean energy conversion processes.By applying a genetic algorithm based global optimization,we identified new surface phases at relatively high O coverages,1 ML and 3/2 ML,on Pt and Pt alloy(111)surfaces.The existence of O transforms the metallic surfaces,creating oxide skins with different morphology and composition.Metals with higher reducibility are pulled out to the outmost surface,to bind with O atoms.The lattice constant affects the binding strength of O atoms over certain oxide skins.Moreover,the strain effect plays a crucial role in the formation of oxide overlayers.展开更多
Developing a descriptor to understand the reactivity of a catalyst is critical in achieving the rational design of heterogeneous catalysts.Ideally,the descriptor should be simple,predictive,as well as applicable to di...Developing a descriptor to understand the reactivity of a catalyst is critical in achieving the rational design of heterogeneous catalysts.Ideally,the descriptor should be simple,predictive,as well as applicable to diverse types of reactions.This paper describes the development of a descriptor that could meet such ideal requirements based on its element-specific fundamental property,ionization energy.Our results indicated that ionization energies could be utilized to describe successfully the adsorption energies of oxygen(O*)and hydroxyl(OH*)groups on various materials.Moreover,we constructed a bond formation scheme to parse this phenomenon.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFA0705201)the National Natural Science Foundation of China(No.U2032129).
文摘Broadband photodetectors with self-driven functions have attracted intensive scientific interest due to their low energy consumption and high optical gain.However,high-performance broadband self-driven photodetectors are still a significant challenge due to the complex fabrication processes,environmental toxicity,high production costs of traditional 3D semiconductor materials and sharply raised contact resistance,severe interfacial recombination of 2D materials and 2D/3D mixed dimension heterojunction.Here,1D p-Te/2D n-Bi_(2)Te_(3) heterojunctions are constructed by the simple and low-cost hydrothermal method.1D p-Te/2D n-Bi_(2)Te_(3) devices are applied in photoelectrochemical(PEC)photodetectors,with their high performance attributed to the good interfacial contacts reducing interface recombination.The device demonstrated a broad wavelength range(365–850 nm)with an Iph/Idark as high as 377.45.The R_(i),D^(*),and external quantum efficiency(EQE)values of the device were as high as 12.07 mA/W,5.87×10^(10) Jones,and 41.05%,respectively,which were significantly better than the performance of the prepared Bi_(2)Te_(3) and Te devices.A comparison of the freshly fabricated device and the device after 30 days showed that 1D p-Te/2D n-Bi_(2)Te_(3) had excellent stability with only 18.08%decay of photocurrent.It is anticipated that this work will provide new emerging material for future design and preparation of a high-performance self-driven broadband photodetector.
基金supported by the National Key Research and Development Program of China,(No.2019YFA0705201)the National Natural Science Foundation of China(No.U2032129)。
文摘Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To date,most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis.However,a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered.Here,a series of TiO_(2-X)mesoporous spheres(MS)with different oxygen vacancy concentrations for photocatalytic applications were prepared by hightemperature chemical reduction.The link between oxygen vacancy concentration and photocatalytic performance was successfully established.The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration,which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis.As the reduction temperature rises to 300℃,carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs,thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants,as demonstrated by a hydrogen evolution rate of 523.7μmol g^(-1)h^(-1)and a ninefold higher RhB photodegradation rate compared to TiO_(2)MS.The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.
基金National Natural Science Foundation of China,Grant/Award Number:52006005Academic Research Fund of Ministry of Education Singapore,Grant/Award Number:Projects MOE Tier 1,RG 98/18。
文摘Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions,drug delivery,and functional material synthesis.Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control.Specifically,Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration.Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions,where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact.We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields,which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement.Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale,which could shed light on new possibilities in key fields of controlled chemistry reaction,medicine synthesis,and energy generation.
基金supported by the National Natural Science Foundation of China(grant 61975253)the Science and Technology Commission of Shanghai Municipality(grant 21N31900200)the National Infrastructures for Translational Medicine(Shanghai) and the Lumieres(Xu Yuan)Biotechnology Company.
文摘Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing applications.Here we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon resonance.In this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal cavity.The quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar substrate.Such an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level concentrations.Therefore,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing technologies.At the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.
基金financially supported by the National Natural Science Foundation of China(21525626)the Program of Introducing Talents of Discipline to Universities(B06006)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar) at Shanghai Institutions of Higher Learningthe Startup Fund from Fudan University
文摘Templated growth is an important synthetic strategy for the construction of complex multicomponent nanostructures [1-3]. The commonly-used templates can be made from either “hard” materials [4-7](e.g., silica) or "soft" materials (e.g., micelles [8], polymers [9], supramolecules [10], etc.). Hard templates typically allow for good crystallinity of the final nanostructures and better preservation of the geometric feature of original templates [7,11], while soft templates are relatively easy to prepare and remove during the synthesis [12,13]. Recently, polymer- tethered inorganic nanoparticle (NP) assemblies (e.g., one-dimensional chains [14-17], two-dimensional sheets [18], and three-dimensional vesicles [19]) have attracted reasonable attention for their potential applications in diverse fields, such as bio-imaging and drug delivery [16] and surfece enhanced Raman scattering (SERS)[20]. Furthermore, these polymer-inorganic NP assemblies can serve as a new class of mixed soft-hard colloidal template for the fabrication of unconventional nanostructures. For instance, Nie and co-authors [21] firstly synthesized a variety of coaxial-like and Saturn-like multicomponent nanostructures by selective deposition of metals (e.g., Pd, Pt, Ag, Ni, etc.) or metal oxides (e.g., CeO2 and Cu2O) on seed Au NPs organized in polymer- Au NP assemblies, followed by dissociation of the assemblies. Nevertheless, there remains a challenge to precisely control the selective depos让ion of growth materials on the mixed soft-hard templates.
基金We acknowledge the National Key Research and Development Program of China(2016YFB0600901)the National Science Foundation of China(21525626,21761132023,and 21606169)the Program of Introducing Talents of Discipline to Universities(B06006)for financial support.
文摘Noble metal alloys are one of the most commonly used heterogeneous catalysts.During many reactions,the surface composition and oxidation states of the noble metal alloy particles have been reported to be dynamic.This paper describes a density functional theory study to explore the initial oxidation stages of the Ptbased surfaces,which are widely-used catalysts in various clean energy conversion processes.By applying a genetic algorithm based global optimization,we identified new surface phases at relatively high O coverages,1 ML and 3/2 ML,on Pt and Pt alloy(111)surfaces.The existence of O transforms the metallic surfaces,creating oxide skins with different morphology and composition.Metals with higher reducibility are pulled out to the outmost surface,to bind with O atoms.The lattice constant affects the binding strength of O atoms over certain oxide skins.Moreover,the strain effect plays a crucial role in the formation of oxide overlayers.
基金supported from the National Natural Science Foundation of China(nos.21525626,21761132023,and 21676181)the Program of Introducing Talents of Discipline to Universities(no.B06006)。
文摘Developing a descriptor to understand the reactivity of a catalyst is critical in achieving the rational design of heterogeneous catalysts.Ideally,the descriptor should be simple,predictive,as well as applicable to diverse types of reactions.This paper describes the development of a descriptor that could meet such ideal requirements based on its element-specific fundamental property,ionization energy.Our results indicated that ionization energies could be utilized to describe successfully the adsorption energies of oxygen(O*)and hydroxyl(OH*)groups on various materials.Moreover,we constructed a bond formation scheme to parse this phenomenon.
