Optical responses of metallic plasmonic arrays under the localized excitation

The metallic plasmonic array that can support both propagating surface plasmon polaritons(PSPPs)and localized surface plasmon resonance(LSPR)possesses rich optical properties and remarkable optical performance,making it a powerful platform for applications in photonics,chemistry,and materials.For practical applications,the excitation spot is usually smaller than the area of metal arrays.It is thus imperative to address“how many array units are enough?”towards a rational design of plasmonic nanostructures.Herein,we employed focused ion beam(FIB)to precisely fabricate a series of plasmonic array structures with increased unit number.By utilizing photoluminescence(PL)and surface-enhanced Raman spectroscopy(SERS),we found that the array units outside the excitation spot still have a significant impact on the optical response within the spot.Combined with the numerical simulation,we found that the boundary of the finite array leads to the loss of PSPP outside the excitation point,which subsequently affects the coupling of PSPP and LSPR in the excitation spot,leading to variations in PL and SERS intensity.Based on the findings,we further tuned the LSPR mode of the metal arrays by electrodeposition to obtain strong near-field enhancement without any influence on the PSPP mode.This work advances the understanding of near-field and far-field optical behavior in finite-size array structures and provides guidance for designing highly-efficient photonic devices.

碱金属离子诱导亚稳相钌纳米晶合成

亚稳相金属纳米晶因其优异的物理化学性质备受关注,然而如何可控合成亚稳相结构依然面临诸多挑战.本文报道了碱金属离子诱导亚稳相钌纳米晶(面心立方相)的可控合成策略.研究表明钌纳米晶结构和碱金属离子半径密切相关,因此通过改变碱金属离子实现了面心立方相和六方密堆相比例的连续调控.理论计算结果表明,碱金属的存在导致面心立方相的形成能低于六方密堆相,并且这种能量差随着碱金属离子半径的增大而增大.本工作为拓展亚稳态结构的实际应用奠定了基础.

Surface Engineered Ru_(2)Ni Multilayer Nanosheets for Hydrogen Oxidation Catalysis

The hydrogen oxidation reaction(HOR)in alkaline conditions is of great importance for the application of anion exchange membrane fuel cells(AEMFCs).However,the electrocatalysts for alkaline HOR generally suffer from the disadvantage of sluggish kinetics.Herein,we have fabricated Ru2Ni multilayered nanosheets(Ru2Ni MLNSs)in the layer-by-layer manner and engineered the surface properties via postannealing for efficient alkaline HOR.Detailed investigations reveal that such annealing at different temperatures can alter the surface properties of Ru2Ni MLNSs and thus regulate their adsorption abilities toward*H and*OH.In particular,the optimal catalyst exhibits a mass activity of 4.34 A mgRu−1 at an overpotential of 50 mV,which is 18.1 and 13.2 times higher than those of Ru/C(0.24 A mgRu−1)and Pt/C(0.33 A mgPt−1),respectively.Theoretical calculations indicate that the presence of surface O atoms can facilitate the HOR activity while the excessive coverage of O atoms on Ru2Ni surface leads to the strengthened H binding and the decay of HOR activity.This work not only provides an efficient catalyst for alkaline HOR,but it also may shed new light on the design of high-performance catalysts for electrocatalysis and beyond.We have fabricated Ru2Ni multilayer nanosheets(Ru2Ni MLNSs)and realized the surface engineering via an annealing process.Detailed investigations show that such surface engineering can regulate the surface properties and thus promote the alkaline HOR activity.Consequently,the optimal catalyst exhibits a much higher activity than those of commercial Ru/C and Pt/C and is a promising catalyst for alkaline HOR.

界面工程促进雪花状Ru/RuO_(2)纳米片氢气氧化性能

近年来,贵金属钌(Ru)因其具备与铂(Pt)媲美的氢吸附能以及比铂更低的价格被认为是很有前景的氢氧化反应(HOR)和析氢反应(HER)催化剂.然而,目前钌基催化剂在HOR和HER上的大规模应用依然受限于其活性低、稳定性不高等缺点.本文采用湿化学和热处理结合策略制备了具有Ru/RuO_(2)界面的二维雪花纳米片(Ru/RuO_(2) SNSs).表征和理论计算结果表明, Ru/RuO_(2) SNSs的界面结构与热处理温度密切相关.因此,可通过改变热处理温度调控界Ru/RuO_(2)界面相互作用,并进一步调控催化剂表面的氢结合能(HBE)和氢氧根结合能(OHBE),从而提高HOR和HER的催化性能.当Ru/RuO-12 SNSs用于催化碱性HOR时,在50 mV的过电位为下,其质量活性达到了9.13 A mgRu,分别是Ru SNSs(0.14 A mg^(-1)_(Ru))、RuO_(2) SNSs(0.03 A mg^(-1)_(Ru))和商用Pt/C(0.43 A mg^(-1)_(Ru))的65倍、304倍和21倍.此外, Ru/RuO_(2) SNSs还表现出优异的碱性HER性能.在1 mol L^(-1) KOH中,当电流密度达到10 mA cm^(-2)时,过电位低至20.2 mV.这项工作不仅开发了一种高效的HOR和HER催化剂,而且对开发新型高效催化剂也起到了重要的推动作用.