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| 1 | Bound states in the continuum in all-dielectric metasurfaces with scaled lattice constants显示文摘Bound states in the continuum(BICs)have emerged as an efficient tool for trapping light at the nanoscale,promising several exciting applications in photonics.Breaking the structural symmetry has been proposed as an effective way of exciting quasiBICs(QBICs)and generating high-Q resonances.Herein,we demonstrate that QBICs can be excited in an all-dielectric metasurface by scaling the lattice of the metasurface,causing translational symmetry breaking.The corresponding BICs arise from band folding from the band edge to the Γ point in the first Brillouin zone.Multipole analysis reveals that the toroidal dipole dominates these QBICs.Furthermore,scaling the lattice along different directions provides additional freedom for tailoring QBICs,enabling polarization-dependent or-independent QBICs.In addition,this allows the realization of two QBICs at different wavelengths using plane-wave illumination with different polarizations on the metasurface.We experimentally demonstrated the existence of these BICs by fabricating silicon metasurfaces with scaled lattices and measuring their transmission spectra.The vanished resonant linewidth identifies BICs in the transmission spectrum,and the QBICs are characterized by highQ Fano resonances with the Q-factor reaching 2000.Our results have potential applications in enhancing light-matter interaction,such as laser,nonlinear harmonic generation,and strong coupling. | Mimi Zhou Shaojun You Lei Xu Menghui Fan Jing Huang Wenbin Ma Mingzhe Hu Shengyun Luo Mohsen Rahmani Ya Cheng Lin Li Chaobiao Zhou Lujun Huang Andrey E.Miroshnichenko | 2023 | Science China(Physics,Mechanics & Astronomy)2023，66，12： | 0 |
| 2 | Enhancing the electrocatalytic performance of nitrate reduction to ammonia by in-situ nitrogen leaching显示文摘Electrochemical nitrate reduction reaction (NITRR) is regarded as a “two birds-one stone” method for the treatment of nitrate contaminant in polluted water and the synthesis of valuable ammonia, which is retarded by the lack of highly reactive and selective electrocatalysts .Herein, for the first time, nickel foam supported Co_(4) N was designed as a high-performance NITRR catalyst by an in-situ nonmetal leaching-induced strategy.At the optimal potential, the Co_(4) N/NF catalyst achieves ultra-high Faraday efficiency and NH_(3) selectivity of 95.4% and 99.4%, respectively.Ex situ X-ray absorption spectroscopy (XAS), together with other experiments powerfully reveal that the nitrogen vacancies produced by nitrogen leaching are stable and play a key role in boosting nitrate reduction to ammonia.Theoretical calculations confirm that Co_(4) N with abundant nitrogen vacancies can optimize the adsorption energies of NO_(3)^(-) and intermediates, lower the free energy (Δ G ) of the potential-determining step (*NH_(3) to NH_(3) ) and inhibit the formation of N-containing byproducts.In addition, we also conclude that the nitrogen vacancies can stabilize the adsorbed hydrogen, making H_(2) quite difficult to produce, and lowering ΔG from *NO to *NOH, which facilitates the selective reduction of nitrate.This study reveals significant insights about the in-situ nonmetal leaching to enhance the NITRR activity. | Mimi Fu Yini Mao Hua Wang Wei Luo Yimin Jiang Wei Shen Ming Li Rongxing He | 2024 | Chinese Chemical Letters2024，35，2： | 0 |
| 3 | Numerical Study of Interaction Efficiency for a 170GHz Megawatt-Level Coaxial-Gyrotron显示文摘The beam-wave interaction efficiency of a 170GHz megawatt-level corrugated coaxial-gyrotron operating with TE_(31,12) mode was studied numerically. According to the self-consistent nonlinear theory, the efficiencies of two types of coaxial resonator were calculated and compared. Taking into account electronic velocity spread and cavity wall resistivity, the beam-wave interactions of improved cavity were investigated. The relationships between efficiency and magnetic field, voltage, current, beam radius, velocity ratio, and parameters of groove are presented. The results show that the voltage and magnetic field have great influence on efficiency, but the current and velocity spread do slightly. The optimized geometry parameters can improve efficiency, reduce the impact of velocity spread on efficiency, and achieve around 48.6% electronic efficiency and 1.7MW output power at 5% velocity spread and 6.896×10^(-8) Ωm resistivity. | QIN Mimi YANG Kuo LUO Wenguang LUO Yong HUANG Yong | 2016 | Chinese Journal of Electronics2016，25，5： | 0 |
| 4 | Constructing crystalline homophase carbon nitride S-scheme heterojunctions for efficient photocatalytic hydrogen evolution显示文摘The number of photogenerated carriers involved in the photocatalytic reaction is one of the main factors influencing the photocatalytic activity,and constructing S-scheme heterojunctions can significantly en-hance the migration of photogenerated carriers,which is regarded as an effective method.In this study,Au nanoparticles(NPs)-supported crystallized heptazine/triazine-based carbon nitride(AHTCN)S-scheme heterojunction photocatalysts are successfully prepared by photoreduction methods.Except for the Au NPs function as an electron mediator,the experiment results and DFT calculations demonstrate that the Fermi energy level of crystallized heptazine/triazine-based heterojunction(HTCN)is pulled down after anchoring Au NPs,and thus the electron transfer path of HTCN changed from Type II-scheme to S-scheme.Owing to S-scheme heterojunction,the optimal AHTCN-2(2 wt.%Au loaded)exhibits the best photocat-alytic hydrogen evolution with a production rate of 715.2μmol h^(−1)g^(−1),which significantly outperforms that of the HTCN.This work delivers a new strategy for the construction of S-scheme heterojunctions. | Mimi Luo Guanjie Jiang Min Yu Yupeng Yan Zhangjie Qin Yang Li Qin Zhang | 2023 | Journal of Materials Science & Technology2023，，30： | 0 |
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