Highly efficient 1D p-Te/2D n-Bi_(2)Te_(3) heterojunction self-driven broadband photodetector

Broadband photodetectors with self-driven functions have attracted intensive scientific interest due to their low energy consumption and high optical gain.However,high-performance broadband self-driven photodetectors are still a significant challenge due to the complex fabrication processes,environmental toxicity,high production costs of traditional 3D semiconductor materials and sharply raised contact resistance,severe interfacial recombination of 2D materials and 2D/3D mixed dimension heterojunction.Here,1D p-Te/2D n-Bi_(2)Te_(3) heterojunctions are constructed by the simple and low-cost hydrothermal method.1D p-Te/2D n-Bi_(2)Te_(3) devices are applied in photoelectrochemical(PEC)photodetectors,with their high performance attributed to the good interfacial contacts reducing interface recombination.The device demonstrated a broad wavelength range(365–850 nm)with an Iph/Idark as high as 377.45.The R_(i),D^(*),and external quantum efficiency(EQE)values of the device were as high as 12.07 mA/W,5.87×10^(10) Jones,and 41.05%,respectively,which were significantly better than the performance of the prepared Bi_(2)Te_(3) and Te devices.A comparison of the freshly fabricated device and the device after 30 days showed that 1D p-Te/2D n-Bi_(2)Te_(3) had excellent stability with only 18.08%decay of photocurrent.It is anticipated that this work will provide new emerging material for future design and preparation of a high-performance self-driven broadband photodetector.

One-step fabrication of moon-shaped microrobots through in situ solidification of magnetic Janus droplets in microchannels

Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions,drug delivery,and functional material synthesis.Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control.Specifically,Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration.Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions,where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact.We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields,which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement.Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale,which could shed light on new possibilities in key fields of controlled chemistry reaction,medicine synthesis,and energy generation.

金属在高分子-金纳米颗粒复合纳米链上的区域选择性生长（英文）

模板法是可控合成复合纳米材料的一种重要手段.然而,纳米材料在模板,尤其是复合模板上的选择性生长仍面临巨大挑战.本文以自组装聚乙烯-金纳米颗粒一维复合纳米链为软-硬复合模板,实现金属在该模板上可控地选择性沉积、生长.通过选择恰当的表面活性剂来调节金属生长的热力学,金属可以选择性地生长在金纳米颗粒的表面,得到金属间歇包覆的复合纳米链;也可以同时包覆在聚乙烯和金纳米颗粒的表面,得到金属完全包覆的豌豆荚状复合纳米链.不同的包覆方式和包覆材料选择都会导致材料光学性质的变化.时间差分有限元模拟表明,金包覆的豌豆荚状复合纳米链的表面金壳层和内部金纳米颗粒之间存在极强的表面等离子体耦合作用.在表面增强拉曼实验中,该复合纳米链表现出很强的增强信号.

A quasi-3D Fano resonance cavity on optical fiber end-facet for high signal-to-noise ratio dip-and-read surface plasmon sensing

Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing applications.Here we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon resonance.In this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal cavity.The quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar substrate.Such an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level concentrations.Therefore,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing technologies.At the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.

Exploring the initial oxidation of Pt,Pt_(3)Ni,Pt_(3)Au(111)surfaces:a genetic algorithm based global optimization with density functional theory

Noble metal alloys are one of the most commonly used heterogeneous catalysts.During many reactions,the surface composition and oxidation states of the noble metal alloy particles have been reported to be dynamic.This paper describes a density functional theory study to explore the initial oxidation stages of the Ptbased surfaces,which are widely-used catalysts in various clean energy conversion processes.By applying a genetic algorithm based global optimization,we identified new surface phases at relatively high O coverages,1 ML and 3/2 ML,on Pt and Pt alloy(111)surfaces.The existence of O transforms the metallic surfaces,creating oxide skins with different morphology and composition.Metals with higher reducibility are pulled out to the outmost surface,to bind with O atoms.The lattice constant affects the binding strength of O atoms over certain oxide skins.Moreover,the strain effect plays a crucial role in the formation of oxide overlayers.

Predicting the Catalytic Activity of Surface Oxidation Reactions by Ionization Energies

Developing a descriptor to understand the reactivity of a catalyst is critical in achieving the rational design of heterogeneous catalysts.Ideally,the descriptor should be simple,predictive,as well as applicable to diverse types of reactions.This paper describes the development of a descriptor that could meet such ideal requirements based on its element-specific fundamental property,ionization energy.Our results indicated that ionization energies could be utilized to describe successfully the adsorption energies of oxygen(O*)and hydroxyl(OH*)groups on various materials.Moreover,we constructed a bond formation scheme to parse this phenomenon.