We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by...We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by an analytical method and compared with those on planar substrates. Based on our theory, the bend of graphene nearly does not affect the property of GSPPs except for an extremely small shift to the lower frequency for the same effective mode index. The field distributions and the eigenfrequencies of GSPPs on planar and cylindrical substrates are calculated by the finite element method, which validates our theoretical analysis. Moreover, three types of graphene-guided optical interconnections of GSPPs, namely, planar to curved graphene film, curved to planar graphene film, and curved to curved graphene film, are proposed and examined in detail. The theoretical results show that the GSPPs propagation on curved graphene substrates and interconnections will not induce any additional losses if the phase-matching condition is satisfied. Additionally, the extreme tiny size of curved graphene for interconnection at a certain spectra range is predicted by our theory and validated by the simulation of 90° turning of GSPPs. The bending effect on the property of GSPPs is systematically analyzed and identified. Our studies would be helpful to instruct design of plasmonic devices involving curved GSPPs, such as nanophotoniccircuits, flexible plasmonic, and biocompatible devices.展开更多
Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures....Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures.However,the role of SACs supports on the catalytic performance does not receive enough research attentions.Here,we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions(ZnN/CNO).ZnN/CNO catalysts show an excellent high selectivity for CO_(2) electro-reduction to CO with a Faradaic efficiency of CO(FECO)up to 97%at -0.47 V(vs.reversible hydrogen electrode,RHE)and remarkable durability without activity decay.To our knowledge,ZnN/CNO is the best activity for the Zn based catalysts up to now,and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate,although the graphene with larger surface area.The exact role of such carbon nano-onions(CNO)support is studied systematically by coupling characterizations and electrochemistry with density functional theory(DFT)calculations,which have attributed such good performance to the increased curvature.Such increased curvature modifies the surface charge,which then changes the adsorption energies of key intermediates,and improves the selectivity for CO generation accordingly.展开更多
Many studies have examined the design,fabrication and characteristics of gecko-inspired adhesives,but applied research on gecko-inspired surfaces in humanoid dexterous hands is relatively scarce.Here,a wedged slanted ...Many studies have examined the design,fabrication and characteristics of gecko-inspired adhesives,but applied research on gecko-inspired surfaces in humanoid dexterous hands is relatively scarce.Here,a wedged slanted structure with a curved substrate suitable for humanoid dexterous fingers was designed and manufactured via ultraprecision machining and replica molding.The adhesion and friction properties of the wedged slanted structure show obvious anisotropic characteristics in the gripping and releasing directions,and the influence of structural parameters and motion parameters on the adhesion and friction was systematically studied.The humanoid dexterous fingers with gecko-inspired surfaces greatly increased the grasping force limit(increase to 4.02 times)based on the grasping of measuring cups with different volumes of water and improved the grasping stability based on the picking up of smooth steel balls of different diameters.This study shows that this process,based on ultraprecision machining and replica molding,is a green,high-efficiency,and low-cost method to fabricate large-area biomimetic surfaces that has potential applications in dexterous humanoid hands to improve grasping ability,stability and adaptability.展开更多
基金supported by the 973 Program of China (nos. 2013CB632704 and 2011CB922002)the National Natural Science Foundation of China (no. 11204365)
文摘We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by an analytical method and compared with those on planar substrates. Based on our theory, the bend of graphene nearly does not affect the property of GSPPs except for an extremely small shift to the lower frequency for the same effective mode index. The field distributions and the eigenfrequencies of GSPPs on planar and cylindrical substrates are calculated by the finite element method, which validates our theoretical analysis. Moreover, three types of graphene-guided optical interconnections of GSPPs, namely, planar to curved graphene film, curved to planar graphene film, and curved to curved graphene film, are proposed and examined in detail. The theoretical results show that the GSPPs propagation on curved graphene substrates and interconnections will not induce any additional losses if the phase-matching condition is satisfied. Additionally, the extreme tiny size of curved graphene for interconnection at a certain spectra range is predicted by our theory and validated by the simulation of 90° turning of GSPPs. The bending effect on the property of GSPPs is systematically analyzed and identified. Our studies would be helpful to instruct design of plasmonic devices involving curved GSPPs, such as nanophotoniccircuits, flexible plasmonic, and biocompatible devices.
基金This work was supported by the National Key R&D Program of China(2020YFA0710404)the Beijing Natural Science Foundation(2182077)the National Natural Science Foundation of China(21477136,51972281,and 21703250).
文摘Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures.However,the role of SACs supports on the catalytic performance does not receive enough research attentions.Here,we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions(ZnN/CNO).ZnN/CNO catalysts show an excellent high selectivity for CO_(2) electro-reduction to CO with a Faradaic efficiency of CO(FECO)up to 97%at -0.47 V(vs.reversible hydrogen electrode,RHE)and remarkable durability without activity decay.To our knowledge,ZnN/CNO is the best activity for the Zn based catalysts up to now,and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate,although the graphene with larger surface area.The exact role of such carbon nano-onions(CNO)support is studied systematically by coupling characterizations and electrochemistry with density functional theory(DFT)calculations,which have attributed such good performance to the increased curvature.Such increased curvature modifies the surface charge,which then changes the adsorption energies of key intermediates,and improves the selectivity for CO generation accordingly.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB1305300)the National Natural Science Foundation of China(Grant Nos.61733001,61873039,U1713215,U1913211,and U2013602)the China Postdoctoral Science Foundation(Grant No.2021M690017)。
文摘Many studies have examined the design,fabrication and characteristics of gecko-inspired adhesives,but applied research on gecko-inspired surfaces in humanoid dexterous hands is relatively scarce.Here,a wedged slanted structure with a curved substrate suitable for humanoid dexterous fingers was designed and manufactured via ultraprecision machining and replica molding.The adhesion and friction properties of the wedged slanted structure show obvious anisotropic characteristics in the gripping and releasing directions,and the influence of structural parameters and motion parameters on the adhesion and friction was systematically studied.The humanoid dexterous fingers with gecko-inspired surfaces greatly increased the grasping force limit(increase to 4.02 times)based on the grasping of measuring cups with different volumes of water and improved the grasping stability based on the picking up of smooth steel balls of different diameters.This study shows that this process,based on ultraprecision machining and replica molding,is a green,high-efficiency,and low-cost method to fabricate large-area biomimetic surfaces that has potential applications in dexterous humanoid hands to improve grasping ability,stability and adaptability.
