Self-Catalyzed Rechargeable Lithium-Air Battery by in situ Metal Ion Doping of Discharge Products: A Combined Theoretical and Experimental Study

Lithium-air battery has emerged as a viable electrochemical energy technology;yet a substantial overpotential is typically observed,due to the insulating nature of the discharge product Li_(2)O_(2) that hinders the reaction kinetics and device performance.Furthermore,finite solid–solid/-liquid interfaces are formed between Li_(2)O_(2) and catalysts and limit the activity of the electrocatalysts in battery reactions,leading to inadequate electrolytic efficiency.Herein,in-situ doping of Li_(2)O_(2) by select metal ions is found to significantly enhance the lithium-air battery performance,and Co^(2+)stands out as the most effective dopant among the series.This is ascribed to the unique catalytic activity of the resulting Co-O_(x) sites towards oxygen electrocatalysis,rendering the lithium-air battery self-catalytically active.Theoretical studies based on density functional theory calculations show that structural compression occurs upon Co^(2+)doping,which lowers the energy barrier of Li_(2)O_(2) decomposition.Results from this study highlight the significance of in situ electrochemical doping of the discharge product in enhancing the performance of lithium-air battery.

Generation of a Four-Particle Cluster State and Perfect Teleportation of an Arbitrary Two-Particle State in an Ion-Trap System

We propose a scheme for generating a four-particle cluster state in an ion-trap system.The scheme isinsensitive to the thermal motion of the ions,and needs less operations than previous ones.With such a setup,we alsodemonstrate a procedure for perfectly teleporting an arbitrary two-particle state via a single multipartite entanglementchannel,a four-particle cluster state.

MoiréMetasurface with Triple-Band Near-Perfect Chirality

Chiral metasurfaces have been proven to possess great potential in chiroptical applications.However,the multiband chiral metasurface with near-perfect circular dichroism has not been well studied.Also,the widely used bilayer metasurface usually suffers from the interlayer alignment and weak resonance.Here,we propose a twisted Moirémetasurface which can support three chiral bands with near-unity circular dichroism.The Moirémetasurface can remove the restriction of interlayer alignment,while maintaining a strong monolayer resonance.The two chiral bands in the forward direction can be described by two coupled-oscillator models.The third chiral band is achieved by tuning the interlayer chiral mode on resonance with the intralayer mode,to eliminate the parallel and converted components simultaneously.Finally,we study the robustness and tunability of the triple-layer Moirémetasurface in momentum space.This work provides a universal method to achieve three near-unity circular dichroism bands in one metasurface,which can promote applications of chiral metasurfaces in multiband optical communication,chiral drug separation,sensing,optical encryption,chiral laser,nonlinear and quantum optics,etc.

Ultralong cycle life enabled by in situ growth of CoMo_(1-x)P/Mo heterostructure for lithium-sulfur batteries

Lithium-sulfur batteries(Li-S batteries) are considered as promising new-generation electrochemical energy storage devices due to their extremely high theoretical energy density(2600 Wh kg-1) and theoretical specific capacity(1675 m Ah g^(-1)). However, numerous problems such as poor conductivity and the shuttle effect during discharge-charge process limit the practical application of lithium-sulfur batteries. In this work, porous tubular Co Mo_(1-x)P/Mo constructed by in situ growth of metal Mo was designed as the sulfur host for lithium-sulfur batteries. The introduction of Mo modulated the electronic structure of Co Mo P to improve the conductivity of cathode and facilitate the redox kinetics, as well as the Co Mo_(1-x)P/Mo heterostructure was beneficial to inhibit the shuttle effect through the interaction with lithium polysulfides, which improved cycling stability. As a result, Co Mo_(1-x)P/Mo/S cathode had a low-capacity decay rate of only 0.029% per cycle after 2000 cycles at 0.5 C. This work provided a new perspective for the further design of high-performance lithium-sulfur battery cathode materials.

Teleportation of an Arbitrary Two-Particle State via a Single Cluster-Class State

Teleportation of an arbitrary two-qubit state with a single partially entangled state,a four-qubit linearcluster-class state,is studied.The case is more practical than previous ones using maximally entangled states as thequantum channel.In order to realize teleportation,we first construct a cluster-basis of 16 orthonormal cluster states.We show that quantum teleportation can be successfully implemented with a certain probability if the receiver can adoptappropriate unitary transformations after receiving the sender's cluster-basis measurement information.In addition,animportant conclusion can be obtained that a four-qubit maximally entangled state (cluster state) can be extracted froma single copy of the cluster-class state with the same probability as the teleportation in principle.

Concentration effect of the near-infrared quantum cutting of 1788-nm luminescence of Tm^(3+) ion in(Y_(1-x)Tm_x)_3Al_5O_(12) powder phosphor

In the present paper, the concentration effect of near-infrared quantum cutting of Tm3+ion in(Y1-xTmx)3Al5O12powder phosphor is studied by means of experiments and calculations. In addition, the absorption spectra, visible-to-nearinfrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that(Y1-xTmx)3Al5O12powder phosphor has a strong four-photon near-infrared quantum cutting luminescence of 1788.0-nm3F4→3H6fluorescence of Tm3+ion, when excited by 357.0-nm light. It is also found that the up-limit of the four-photon near-infrared quantum cutting luminescence efficiency of(Y0.700Tm0.300)3Al5O12powder phosphor is approximately 302.19%. To the knowledge of the authors, this is the first time that a near-infrared quantum cutting efficiency up-limit exceeding 300% has been reported. The results of this manuscript are valuable in aiding the probing of the new generation Ge solar cell.

W-State Generation and Manipulation for Ion-Trap-Based Quantum-Information Processing

我们为最近为处理任务的几量信息比正规 W 状态更好被显示是的 W 班状态的一种特殊配置的一步舞产生建议一个离子陷井计划。我们也为能把一个正规 W 状态转变成一个充分可分离的状态的重要集体操作的一步舞实现介绍一个方法。如此的转变在最近起一个关键作用建议的量协议。在我们的计划的操作速度与 qubits 的数字增加。这与平常的纠纷产生和随 qubits 的数字的增加花越来越多的时间的量操作计划相反。

Brightening single-photon emitters by combining an ultrathin metallic antenna and a silicon quasi-BIC antenna

Bright single-photon emitters(SPEs)are fundamental components in many quantum applications.However,it is difficult to simultaneously get large Purcell enhancements and quantum yields in metallic nanostructures because of the huge losses in the metallic nanostructures.Herein,we propose to combine an ultrathin metallic bowtie antenna with a silicon antenna above a metallic substrate to simultaneously get large Purcell enhancements,quantum yields,and collection efficiencies.As a result,the brightness of SPEs in the hybrid nanostructure is greatly increased.Due to the deep subwavelength field confinement(mode size<10 nm)of surface plasmons in the ultrathin metallic film(thickness<4 nm),the Purcell enhancement of the metallic bowtie antenna improves by more than 25 times when the metal thickness decreases from 20 nm to 2 nm.In the hybrid nanostructures by combining an ultrathin metallic bowtie antenna with a silicon antenna,the Purcell enhancement(Fp≈2.6×10^(6))in the hybrid nanostructures is 63 times greater than those(≤4.1×10^(4))in the previous metallic and hybrid nanostructures.Because of the reduced ratio of electromagnetic fields in the ultrathin metallic bowtie antenna when the high-index silicon antenna is under the quasi-BIC state,a high quantum yield(QY≈0.70)is obtained.Moreover,the good radiation directivity of the quasi-BIC(bound state in the continuum)mode of the silicon antenna and the reflection of the metallic substrate result in a high collection efficiency(CE≈0.71).Consequently,the overall enhancement factor of brightness of a SPE in the hybrid nanostructure is EF∗≈Fp×QY×CE≈1.3×10^(6),which is 5.6×10^(2) times greater than those(EF∗≤2.2×103)in the previous metallic and hybrid nanostructures.

Highly efficient solution-processed organic photovoltaics enabled by improving packing behavior of organic semiconductors

Solution processability is a unique property of organic semiconductors. The compact and regular π-π stacking between molecules is paramount in the performance of organic optoelectronic devices. However, it is still a challenge to improve their stacking quality without sacrificing the solution-processability from the aspect of materials design. Here, delicately engineered additives are presented to promote the formation of ordered aggregation of conjugated molecules by regulating their nucleation and growth dynamics. Intriguingly, the long-chain BTP-eC9-4F molecules can realize ordered aggregation comparable to short-chain ones without sacrificing processability. The domain size of BTP-eC9-4F aggregation is enlarged from 24.2 to 32.2 nm in blend films.Thereby exciton diffusion and charge transport become faster, contributing to the suppression of recombination losses. As a result, a power conversion efficiency of 19.2% is achieved in D18:BTP-eC9-4F based organic photovoltaics. Our findings demonstrate a facile strategy to improve the packing quality of solution-processed organic semiconductors for high-efficiency photovoltaics and beyond photovoltaics.

In situ decoration of CoP/Ti_(3)C_(2)Tx composite as efficient electrocatalyst for Li-oxygen battery

Application of Li-oxygen(Li-O_(2)) battery is in urgent need of bifunctional ORR/OER electrocatalyst. A surface-functionalization CoP/Ti_(3)C_(2)Txcomposite was fabricated theoretically, with the optimized electronic structure and more active electron, which is beneficial to the electrochemical reaction. The accordion shaped Ti_(3)C_(2)Txis featured with large specific surface area and outstanding electronic conductivity, which is beneficial for the adequate exposure of active sites and the deposition of Li2O2. Transition metal phosphides provide more electrocatalytic active sites and present good electrocatalytic effect. The CoP/Ti_(3)C_(2)Txcomposite served as the electrocatalyst of Li-O_(2)battery reaches a high specific discharge capacity of 17,413 m Ah/g at 100 m A/g and the lower overpotential of 1.25 V, superior to those of the CoP and Ti_(3)C_(2)Txindividually. The composite of transition metal phosphides and MXene are applied in Li-O_(2)battery, not only demonstrating higher cycling stability of the prepared CoP/Ti_(3)C_(2)Txcomposite, but pointing out the direction for their electrochemical performance improvement.

Controlling group velocity in a superconductive quantum circuit

We investigate the controllable group velocity of a microwave probe field in a superconductive quantum circuit(SQC) pumped by microwave fields,and the use of such a SQC function as an artificial Λ-type three-level atom.The exchange between the subluminal and the superluminal states of the probe field can be realized simply by sweeping the pumping intensity,and the superluminal state is usually realized with a lower absorption.This work is one of the efforts to extend the study of electromagnetically induced transparency and its related properties from the lightwave band to the microwave band.

Polarization-switchable plasmonic emitters based on laser-induced bubbles

Owing to weak light-matter interactions in natural materials,it is difficult to dynamically tune and switch emission polariza-tion states of plasmonic emitters(or antennas)at nanometer scales.Here,by using a control laser beam to induce a bubble(n=1.0)in water(n=1.333)to obtain a large index variation as high as|Δn|=0.333,the emission polarization of an ultra-small plasmonic emitter(~0.4λ^(2))is experimentally switched at nanometer scales.The plasmonic emitter consists of two orthogonal subwavelength metallic nanogroove antennas on a metal surface,and the separation of the two anten-nas is only s_(x)=120 nm.The emission polarization state of the plasmonic emitter is related to the phase difference between the emission light from the two antennas.Because of a large refractive index variation(|Δn|=0.333),the phase difference is greatly changed when a microbubble emerges in water under a low-intensity control laser.As a result,the emission polarization of the ultra-small plasmonic emitter is dynamically switched from an elliptical polarization state to a linear polarization state,and the change of the degree of linear polarization is as high asΔγ≈0.66.

Photoinduced excimer generation in perylene diimide dimer:effects of solvent polarity[Invited]

The aggregation and photoinduced excited state dynamics of organic π-conjugated molecules play a vital role in solar energy conversion and applications.This work investigates how solvent polarity affects the aggregation behavior and the photophysical process of perylene diimide dimer(PDI-II).The results show that the conjugations between PDI intramolecular chromophores are more likely to generate excimer,and the conjugations between PDI intermolecular chromophores are more likely to experience symmetry-breaking charge separation.Our study can provide a reference for the design of high-efficiency solar energy conversion materials.

氧化石墨炔提升界面电荷传输及分离以构筑高效二元有机太阳能电池器件

通过界面工程调节载流子动力学是提高太阳能电池器件效率的关键方式.在本工作中,我们成功制备了具有大量官能团的高分散性氧化石墨炔(GDYO),并将其应用于优化空穴传输材料PEDOT:PSS的性质以制备有机太阳能电池器件.结果表明,GDYO与PEDOT:PSS之间的π–π相互作用有利于优化电荷转移通道,提高空穴传输层的电导率和载流子迁移率.此外,界面接触的改善有助于抑制电荷的复合,提高空穴传输层和活性层之间的电荷提取.同时,活性层的形貌得到有效改善,瞬态吸收测试结果证实这有利于载流子分离率的提升,进而提高器件性能.因此,通过对载流子动力学的系统性优化,二元有机太阳能电池的光电转换效率达到17.5%,认证效率达到17.2%.本工作结果表明功能化石墨炔在有机光电器件领域具有广阔的应用前景.

Planarized Polymer Acceptor Featuring High Electron Mobility for Efficient All-Polymer Solar Cells

Significant progress has been achieved for all-polymer solar cells(APSCs)in the last few years by the use of polymerized small molecular acceptors(PSMAs).Developing high electron mobility polymer acceptors has been considered a feasible solution to further improve the photovoltaic performance of APSCs and fabricate thick film devices,which contributed to roll-to-roll printing techniques.In this work,we designed and synthesized PSV,an A-DA’D-A small molecule acceptor-based PSMA with the vinyl group as a bridged linkage to reduce the steric hindrance between the 1,1-dicyanomethylene-3-indanone(IC)terminal group.In comparison with the C-C bond linked polymer acceptor PS,PSV exhibits an almost planar conjugated framework and well-ordered molecular stacking in the thin film.Moreover,PSV exhibits superior n-type semiconducting properties with high electron mobility of up to 0.54 cm^(2)·V^(−1)·s^(−1),which is the highest value among reported PSMAs.By utilizing PM6 as a polymer donor,PSV-based blend forms a favorable nanomorphology and exhibits high and well-balanced hole/electron mobilities,which is beneficial for exciton separation and charge transport.Consequently,APSCs based on PM6:PSV achieved high power conversion efficiencies of up to 15.73%,with a simultaneously realized high Voc of 0.923 V,Jsc of 23.2 mA·cm^(-2),and FF of 0.734.Such superior features enable PSV with excellent thickness-insensitive properties and over 13%PCE was obtained at 300 nm.To the best of our knowledge,the high PCE of 15.73%with excellent electron mobility of 0.54 cm^(2)·V^(−1)·s^(−1)is the highest values reported for APSCs.These results point to the great significance of developing polymer acceptors with a high electron mobility for boosting the performance of APSCs.