Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu...Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.展开更多
In this Letter, we propose the electronic manipulation of localized surface plasmon resonance for active tuning in near-field nanofocusing.We theoretically studied the excited graphene tuning of the nanofocusing field...In this Letter, we propose the electronic manipulation of localized surface plasmon resonance for active tuning in near-field nanofocusing.We theoretically studied the excited graphene tuning of the nanofocusing field in fewlayer graphene(FLG)-based hybrid nanotips.It is revealed that the normalized enhanced electric field can be significantly promoted to more than 300 times.It is also observed that resonant peaks can be unprecedently modified by the electron state of excited graphene that is embedded in the substrate.It shows the possibility of flexible tuning of plasmon resonances via controlling the electron excitation state of graphene for specific advanced near-field nanofocusing applications.展开更多
Terahertz(THz)scattering-type scanning near-field optical microscopy(s-SNOM)is an important means of studying and revealing material properties at the nanoscale.The nanotip is one of the core components of THz s-SNOM,...Terahertz(THz)scattering-type scanning near-field optical microscopy(s-SNOM)is an important means of studying and revealing material properties at the nanoscale.The nanotip is one of the core components of THz s-SNOM,which has a decisive impact on the resolution of the system.In this paper,we focus on the theory and design of the nanotip and conduct comprehensive research on it through simulation.The theoretical model is based on full-wave numerical simulation and dipole moment analysis,which can describe the overall nanotip electromagnetic response under the incident field.A comprehensive design model of nanotip geometry,sample materials,and incident field is established to significantly improve the near-field coupling efficiency and spatial resolution to achieve optimal performance.展开更多
This paper reviews an initial achievement of our group toward the development of on-chip parallel high-speed atomic force microscopy（HS-AFM）.A novel AFM approach based on silicon waveguide cantilever displacement se...This paper reviews an initial achievement of our group toward the development of on-chip parallel high-speed atomic force microscopy（HS-AFM）.A novel AFM approach based on silicon waveguide cantilever displacement sensor is proposed.The displacement sensing approach uniquely allows the use of nano-scale wide cantilever that has a high resonance frequency and low spring constant desired for on-chip parallel HS-AFM.The approach consists of low loss silicon waveguide with nano-gap,highly efficient misalignment tolerant coupler,novel high aspect ratio（HAR）sharp nano-tips that can be integrated with nano-scale wide cantilevers and electrostatically driven nano-cantilever actuators.The simulation results show that the displacement sensor with optical power responsivity of 0.31%/nm and AFM cantilever with resonance frequency of 5.4 MHz and spring constant of 0.21 N/m are achievable with the proposed approach.The developed silicon waveguide fabrication method enables silicon waveguide with 6 and 7.5 dB/cm transmission loss for TE and TM modes,respectively,and formation of 13 nm wide nano-gaps between silicon waveguides.The coupler demonstrates misalignment tolerance of ±1.8 μm for 5μm spot size lensed fiber and coupling loss of 2.12 dB/facet for standard cleaved single mode fiber without compromising other performance.The nano-tips with apex radius as small as 2.5 nm and aspect ratio of more than 50 has been enabled by the development of novel HAR nanotip fabrication technique.Integration of the HAR tips onto an array of 460 nm wide cantilever beam has also been demonstrated.展开更多
基金financially supported by the Major Fundamental Research of Natural Science Foundation of Shandong Province(ZR2022ZD10)National Natural Science Foundation of China(22478211,22372017)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20231193)Liaoning Binhai Laboratory(LBLG-2024-10)Qingdao Postdoctoral Applied Research Project(QDBSH20240102068)。
文摘Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.
基金supported by the National Key Research and Development Program of China(No.2017YFB1104700)the National Natural Science Foundation of China(Nos.51335008,61775177,and 61475124)+2 种基金the NSAF(No.U1630111)the Collaborative Innovation Center of Suzhou Nano Science and Technologythe China Postdoctoral Science Foundation(No.2014M560778)
文摘In this Letter, we propose the electronic manipulation of localized surface plasmon resonance for active tuning in near-field nanofocusing.We theoretically studied the excited graphene tuning of the nanofocusing field in fewlayer graphene(FLG)-based hybrid nanotips.It is revealed that the normalized enhanced electric field can be significantly promoted to more than 300 times.It is also observed that resonant peaks can be unprecedently modified by the electron state of excited graphene that is embedded in the substrate.It shows the possibility of flexible tuning of plasmon resonances via controlling the electron excitation state of graphene for specific advanced near-field nanofocusing applications.
基金supported by the National Natural Science Foundation of China(Nos.12061131010 and 12074198).
文摘Terahertz(THz)scattering-type scanning near-field optical microscopy(s-SNOM)is an important means of studying and revealing material properties at the nanoscale.The nanotip is one of the core components of THz s-SNOM,which has a decisive impact on the resolution of the system.In this paper,we focus on the theory and design of the nanotip and conduct comprehensive research on it through simulation.The theoretical model is based on full-wave numerical simulation and dipole moment analysis,which can describe the overall nanotip electromagnetic response under the incident field.A comprehensive design model of nanotip geometry,sample materials,and incident field is established to significantly improve the near-field coupling efficiency and spatial resolution to achieve optimal performance.
文摘This paper reviews an initial achievement of our group toward the development of on-chip parallel high-speed atomic force microscopy（HS-AFM）.A novel AFM approach based on silicon waveguide cantilever displacement sensor is proposed.The displacement sensing approach uniquely allows the use of nano-scale wide cantilever that has a high resonance frequency and low spring constant desired for on-chip parallel HS-AFM.The approach consists of low loss silicon waveguide with nano-gap,highly efficient misalignment tolerant coupler,novel high aspect ratio（HAR）sharp nano-tips that can be integrated with nano-scale wide cantilevers and electrostatically driven nano-cantilever actuators.The simulation results show that the displacement sensor with optical power responsivity of 0.31%/nm and AFM cantilever with resonance frequency of 5.4 MHz and spring constant of 0.21 N/m are achievable with the proposed approach.The developed silicon waveguide fabrication method enables silicon waveguide with 6 and 7.5 dB/cm transmission loss for TE and TM modes,respectively,and formation of 13 nm wide nano-gaps between silicon waveguides.The coupler demonstrates misalignment tolerance of ±1.8 μm for 5μm spot size lensed fiber and coupling loss of 2.12 dB/facet for standard cleaved single mode fiber without compromising other performance.The nano-tips with apex radius as small as 2.5 nm and aspect ratio of more than 50 has been enabled by the development of novel HAR nanotip fabrication technique.Integration of the HAR tips onto an array of 460 nm wide cantilever beam has also been demonstrated.
