Photocatalytic N_(2)xation has attracted substantial attention in recent years,as it represents a green and sustainable devel-opment route toward effciently convert-ing N_(2)to NH_(3)for industrial applications.How to...Photocatalytic N_(2)xation has attracted substantial attention in recent years,as it represents a green and sustainable devel-opment route toward effciently convert-ing N_(2)to NH_(3)for industrial applications.How to rationally design catalysts in this regard remains a challenge.Here we pro-pose a strategy that uses plasmonic hot electrons in the highly doped TiO_(2)to ac-tivate the inert N_(2)molecules.The synthesized semiconductor catalyst Mo-doped TiO_(2)shows a NH_(3)production effciency as high as 134μmol·g^(-1)·h^(-1)under ambient conditions,which is comparable to that achieved by the conventional plasmonic gold metal.By means of ultra-fast spectroscopy we reveal that the plasmonic hot electrons in the system are responsible for the activation of N_(2)molecules,enabling improvement the catalytic activity of TiO_(2).This work opens a new avenue toward semiconductor plasmon-based photocatalytic N_(2)xation.展开更多
We study the dispersion properties of surface plasmon(SP) oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange(CE) force associated with the spin polarization of electrons a...We study the dispersion properties of surface plasmon(SP) oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange(CE) force associated with the spin polarization of electrons and holes as well as the effects of the Fermi degenerate pressure and the quantum Bohm potential.Starting from a quantum hydrodynamic model coupled to the Poisson equation,we derive the general dispersion relation for surface plasma waves.Previous results in this context are recovered.The dispersion properties of the surface waves are analyzed in some particular cases of interest and the relative influence of the quantum forces on these waves are also studied for a nano-sized Ga As semiconductor plasma.It is found that the CE effects significantly modify the behaviors of the SP waves.The present results are applicable to understand the propagation characteristics of surface waves in solid density plasmas.展开更多
The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semicond...The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density.Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials.We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies.Importantly,InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering,resulting in a reduced carrier mobility thereby damping the plasmonic response.We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers,including flexible nonlinear absorbers achieved by transferring the disks to polyimide films.Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz(THz)optics and for passive protection of sensitive electromagnetic devices.展开更多
Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble...Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO_(3-x), MoO_(3-x), Cu_(2-x)S, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO_(2) reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.展开更多
Heavily doped colloidal plasmonic nanocrystals have attracted great attention because of their lower and adjustable free carrier densities and tunable localized surface plasmonic resonance bands in the spectral range ...Heavily doped colloidal plasmonic nanocrystals have attracted great attention because of their lower and adjustable free carrier densities and tunable localized surface plasmonic resonance bands in the spectral range from near-infra to mid-infra wavelengths.With its plasmon-enhanced optical nonlinearity,this new family of plasmonic materials shows a huge potential for nonlinear optical applications,such as ultrafast switching,nonlinear sensing,and pulse laser generation.Cu3-xP nanocrystals were previously shown to have a strong saturable absorption at the plasmonic resonance,which enabled high-energy Q-switched fiber lasers with 6.1μs pulse duration.This work demonstrates that both high-quality mode-locked and Q-switched pulses at 1560 nm can be generated by evanescently incorporating two-dimensional(2D)Cu3-xP nanocrystals onto a D-shaped optical fiber as an effective saturable absorber.The 3 dB bandwidth of the mode-locking optical spectrum is as broad as 7.3 nm,and the corresponding pulse duration can reach 423 fs.The repetition rate of the Q-switching pulses is higher than 80 kHz.Moreover,the largest pulse energy is more than 120μJ.Note that laser characteristics are highly stable and repeatable based on the results of over 20 devices.This work may trigger further investigations on heavily doped plasmonic 2D nanocrystals as a next-generation,inexpensive,and solution-processed element for fascinating photonics and optoelectronics applications.展开更多
基金This work was supported by the National Key Research and Development Program of China(No.2016YFA0200602 and No.2018YFA0208702)the National Natural Science Foundation of China(No.21633007,No.21573211,No.21803067,and No.91950207)+1 种基金the Anhui Initiative in Quantum In-formation Technologies(No.AHY090200)the USTC-NSRL Joint Funds(No.UN2018LHJJ).
文摘Photocatalytic N_(2)xation has attracted substantial attention in recent years,as it represents a green and sustainable devel-opment route toward effciently convert-ing N_(2)to NH_(3)for industrial applications.How to rationally design catalysts in this regard remains a challenge.Here we pro-pose a strategy that uses plasmonic hot electrons in the highly doped TiO_(2)to ac-tivate the inert N_(2)molecules.The synthesized semiconductor catalyst Mo-doped TiO_(2)shows a NH_(3)production effciency as high as 134μmol·g^(-1)·h^(-1)under ambient conditions,which is comparable to that achieved by the conventional plasmonic gold metal.By means of ultra-fast spectroscopy we reveal that the plasmonic hot electrons in the system are responsible for the activation of N_(2)molecules,enabling improvement the catalytic activity of TiO_(2).This work opens a new avenue toward semiconductor plasmon-based photocatalytic N_(2)xation.
基金financial support of Arak University under research Project No.96/5834UGC-SAP(DRS,Phase Ⅲ)[with Sanction order No.F.510/3/DRS-III/2015(SAPI)]UGC-MRP[with F.No.43-539/2014(SR) and FD Diary No.3668] for support
文摘We study the dispersion properties of surface plasmon(SP) oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange(CE) force associated with the spin polarization of electrons and holes as well as the effects of the Fermi degenerate pressure and the quantum Bohm potential.Starting from a quantum hydrodynamic model coupled to the Poisson equation,we derive the general dispersion relation for surface plasma waves.Previous results in this context are recovered.The dispersion properties of the surface waves are analyzed in some particular cases of interest and the relative influence of the quantum forces on these waves are also studied for a nano-sized Ga As semiconductor plasma.It is found that the CE effects significantly modify the behaviors of the SP waves.The present results are applicable to understand the propagation characteristics of surface waves in solid density plasmas.
基金supported in part by the National Science Foundation under contract ECCS 1309835the Air Force Office of Scientific Research under contract FA9550-09-1-0708+1 种基金support from DOEBasic Energy Sciences under Grant No.DE-FG02-09ER46643,under which the THz measurements were performedsupported by a Multidisciplinary University Research Initiative from the Air Force Office of Scientific Research(AFOSR MURI Award No.FA9550-12-1-0488)。
文摘The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density.Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials.We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies.Importantly,InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering,resulting in a reduced carrier mobility thereby damping the plasmonic response.We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers,including flexible nonlinear absorbers achieved by transferring the disks to polyimide films.Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz(THz)optics and for passive protection of sensitive electromagnetic devices.
基金supported by the National Natural Science Foundation of China (Nos. 11904133, 51872125)Guangdong Natural Science Funds for Distinguished Young Scholar (No. 2018B030306004) and GDUPS (2018)+1 种基金the Fundamental Research Funds for the Central Universities (No. 21619322)Regional Joint Foundation in Guangdong Province (No. 2019A1515110210)。
文摘Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO_(3-x), MoO_(3-x), Cu_(2-x)S, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO_(2) reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.
基金the support from the National Key Research&Development Program(No.2016YFA0201902)Shenzhen Nanshan District Pilotage Team Program(No.LHTD20170006)+1 种基金Australian Research Council(ARC,FT 150100450,IH150100006,and CE170100039)the funding support from China Postdoctoral Science Foundation Grant(No.217M622758).
文摘Heavily doped colloidal plasmonic nanocrystals have attracted great attention because of their lower and adjustable free carrier densities and tunable localized surface plasmonic resonance bands in the spectral range from near-infra to mid-infra wavelengths.With its plasmon-enhanced optical nonlinearity,this new family of plasmonic materials shows a huge potential for nonlinear optical applications,such as ultrafast switching,nonlinear sensing,and pulse laser generation.Cu3-xP nanocrystals were previously shown to have a strong saturable absorption at the plasmonic resonance,which enabled high-energy Q-switched fiber lasers with 6.1μs pulse duration.This work demonstrates that both high-quality mode-locked and Q-switched pulses at 1560 nm can be generated by evanescently incorporating two-dimensional(2D)Cu3-xP nanocrystals onto a D-shaped optical fiber as an effective saturable absorber.The 3 dB bandwidth of the mode-locking optical spectrum is as broad as 7.3 nm,and the corresponding pulse duration can reach 423 fs.The repetition rate of the Q-switching pulses is higher than 80 kHz.Moreover,the largest pulse energy is more than 120μJ.Note that laser characteristics are highly stable and repeatable based on the results of over 20 devices.This work may trigger further investigations on heavily doped plasmonic 2D nanocrystals as a next-generation,inexpensive,and solution-processed element for fascinating photonics and optoelectronics applications.