摘要：量子自旋霍尔绝缘体拥有具有带隙的体态和无能隙的一维拓扑边缘态.然而,由于拓扑边缘态局域在纳米尺度,所以很难用光学手段直接观测并区分体态和边缘态,这就限制了对拓扑边缘态独特的光学特性和光电响应等方面的研究和应用.Bi_(4)Br_(4)体材料的台阶存在一维非平庸的边缘态,多个台阶累加的效应使得通过较为宏观的光学和光电分析手段来研究一维边缘态成为可能.该工作利用中远红外显微吸收光谱和泵浦探测光谱,对比研究了Bi_(4)Br_(4)体和边缘的光学响应行为.研究发现Bi_(4)Br_(4)的边缘在小于带隙(约0.22 eV)的波段存在明显的强于体内的红外吸收,且该吸收呈现较强的各向异性.室温下的红外泵浦探测首次观察到边缘处载流子激发态超长的弛豫时间(1.5 ns),该激发态载流子寿命要比体内载流子寿命长两个量级.该工作证实体态和拓扑边缘态具有明显不同的光学和光电响应行为,为未来设计新型红外探测器提供了材料和物理基础.

摘要：过渡金属硫族化合物(TMD)薄层仅改变几何形状(如层厚)就可调节带隙、电子亲和势和费米能级,使器件设计更灵活。但因缺乏费米能级排列信息,TMD同质/异质结器件常因未知的能带弯曲而偏离预期。利用扫描开尔文探针显微镜(SKPM)表征了TMD同质/异质结,结果显示,Mo S_(2)和Mo Te_(2)同质结的费米能级随层厚增加向本征费米能级移动(背景掺杂浓度降低),而Mo Te_(2)/Mo S_(2)异质结中探测到宽耗尽区和强光响应,同时给出表面污染(分子尺度)对单层TMD表面电势的影响。上述发现将在器件设计中帮助精准堆叠范德华(vdW)层。

摘要：将不同金属元素通过合金化形成二维材料(金属烯)对基础研究和纳米电子器件的实际应用具有重要意义,但目前鲜有金属烯材料是具有本征带隙的半导体.受离子晶体成键特征的启发,通过结构搜索、成键分析和高通量第一性原理计算,本文从2500多个双金属烯中筛选出一系列具有晶格动力学稳定和碱金属-金离子键的二维碱金属金化物双金属烯半导体.由于碱金属和金之间的大电负性差,其中32个碱金属金化物双金属烯是带隙范围为0.97~5.20 eV的半导体材料,而锂金双金属烯由于电负性差减小呈现出金属性.Bohn-Oppenheimer分子动力学模拟表明19个双金属烯在室温下结构稳定有利于实际应用.这项研究为设计双金属烯半导体提供了指导,并揭示了二维金属合金中成键行为和电子结构性质间的关联.

摘要：The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in *** last six years have witnessed tremendous progress in the field of single‐atom *** we introduce the major achievements on this topic *** particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in *** accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.

摘要：Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution ***,because of the spectral line broadening and multiple sites of lanthanide in upconversion particles(UCPs),the crystal-field(CF)polarization components of UCL are usually ***,we report the linearly polarized UCL in LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals with resolvable CF transition lines and a polarization degree up to *** CF levels and CF transition lines of Er^(3+),as well as their emission polarization anisotropy,are unraveled for the first time through low-temperature and high-resolution photoluminescence(PL)and UCL *** taking advantage of the well-resolved and highly-polarized CF transition lines of Er^(3+),we demonstrate the application of LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals as anisotropic UCL probes for orientation *** findings provide fundamental insights into the polarization anisotropy of UCL in lanthanide-doped single particles,thus laying a foundation for the future design of anisotropic luminescent probes towards versatile applications.

摘要：Monitoring the electrophysiology activity of neurons and blood calcium signals can enable a better understanding of disease-related neural system ***,currently,in situ calcium ion monitoring tools are scarce and exhibit low integration and limited *** this letter,we propose an implantable probe with an integrated in situ Ag/AgCl reference electrode(ISA/ARE)that can monitor action potential(AP)and Ca^(2+) concentrations.

摘要：The ever-decreasing size of transistors requires effectively electrostatic control over ultra-thin semiconductor *** design of the gate configuration can fully persevere the intrinsic property of two-dimensional(2 D)*** we design and demonstrate a 2 D Mo S_(2) transistor with omega-shaped gate,in which the local gate coupling is enhanced by the non-planar *** omega-shaped non-planar transistors exhibit a high current of 0.89 A/lm and transconductance of32.7 l S/*** high performance and desirable current saturation promise the construction of robust logic *** inverters show a voltage gain of 26.6 and an ideal total margin nearly 89%.We also assemble NOT-AND(NAND)gate on an individual Mo S_(2) flake,and the constructed NAND gate demonstrates the universal functionality of the transistors as *** work provides an alternative strategy to fully take the advantages of 2 D materials for high-performance field-effect transistors.

摘要：Electrochemical CO2 reduction reaction(CO2RR)powered by renewable electricity has emerged as the most promising technique for CO2 conversion,making it possible to realize a carbon‐neutral *** efficient,robust,and cost‐effective catalysts are highly demanded for the near‐future practical applications of *** studies on atomically dispersed metal‐nitrogen(M‐Nx)sites constituted of earth abundant elements with maximum atom‐utilization efficiency have demonstrated their performance towards *** review summarizes recent advances on a variety of M‐Nx sites‐containing transition metal‐centered macrocyclic complexes,metal organic frameworks,and M‐Nx‐doped carbon materials for efficient CO2RR,including both experimental and theoretical *** roles of metal centers,coordinated ligands,and conductive supports on the intrinsic activity and selectivity,together with the importance of reaction conditions for improved performance are *** mechanisms of CO2RR over these M‐Nx‐containing materials are presented to provide useful guidance for the rational design of efficient catalysts towards CO2RR.

摘要：具有独特局域表面等离子共振散射特性的贵金属纳米粒子,在可见光区域表现出明显的吸收和散射光谱特性。在过去的几十年中,基于纳米金和纳米银溶液的可视化颜色传感器,被广泛应用在金属离子、生物分子、农药等灵敏检测。自2000年,暗场显微镜的出现,实现了纳米尺度下等离子共振散射光谱的精准获取,将传感尺度从传统的实验试管发展到单纳米颗粒界面。单颗粒检测消除了本体溶液中大量纳米粒子产生的平均效应,可提供更加准确的反应信息。纳米粒子的散射光谱主要取决于颗粒的尺寸、形貌、成分以及颗粒间耦合作用等,因此,具有特定散射颜色的单个纳米粒子,可以作为优异的纳米探针。这篇综述聚焦于单颗粒纳米传感,首先介绍了纳米粒子局域表面等离子共振的原理和发展历史。随后,主要讨论了单个贵金属纳米粒子作为颜色编码传感器,在生物分子、环境污染物以及能源等领域的应用,尤其是基于单颗粒的原位纳米光谱电化学传感及其在电催化反应中的应用。例如,利用纳米粒子的溶出和生长过程,精巧地设计了针对不同待测物的纳米探针。另一方面,对单纳米粒子结构演变过程的原位监测,也有助于对纳米材料制备机理的理解。最后,着重探讨了纳米颜色传感器信号提取放大的检测手段,包括将肉眼识别的颜色转换为可读的三原色信息以及偏振光检测技术等,进一步扩展单颗粒颜色传感的应用范围。

摘要：The efficient and stable abatement of CO pollutant under ambient conditions is of great significance;however,it remains a formidable ***,we report the versatile application of wet oxidation over Fe(OH)x supported subnanometer Pt group metal(PGM)catalysts for the complete removal of CO under ambient temperature and humidity ***,the 1.8 wt%Rh/Fe(OH)x catalyst exhibited better durability during a^1400 min run for wet oxidation than for dry CO *** characterization results including HR-TEM,H2-TPR,and in-situ DRIFTS suggested that Fe(OH)x,with good reducibility,promoted by the subnanometer Rh clusters,provided sites for the adsorption and reaction of O2 and H2 O to form OH ***,these OH species reacted with the adsorbed CO on Rh sites with a considerably lower activation energy(9 kJ mol^-1)than that of dissociated 0 species(22 kJ mol^-1),thus rationalizing the outstanding performance of Rh/Fe(OH)x for wet *** experiments with other PGMs revealed a good generality for the application of wet oxidation in the efficient abatement of CO under humid conditions with Fe(OH)x as the support.