Enhancing light absorption for organic solar cells using front ITO nanograting and back ultrathin Al layer

To address the discrepancy between carrier collection and light absorption of organic solar cells caused by the limited carrier mobility and optical absorption coefficient for the normally employed organic photoactive layers,a light management structure composed of a front indium tin oxide(ITO)nanograting and ultrathin Al layer inserted in between the photoactive layer and the electron transport layer(ETL)is introduced.Owing to the antireflection and light scattering induced by the ITO nanograting and the suppression of light absorption in the ETL by the inserted Al layer,the light absorption of the photoactive layer is significantly enhanced in a spectral range from 400 nm to 650 nm that also covers the main energy region of solar irradiation for the normally employed active materials such as the P3HT:PC_(61)BM blend.The simulation results indicate that comparing with the control device with a planar configuration of ITO/PEDOT:PSS/P3HT:PC_(61)BM(80-nm thick)/ZnO/Al,the short-circuit current density and power conversion efficiency of the optimized light management structure can be improved by 32.86%and 34.46%.Moreover,good omnidirectional light management is observed for the proposed device structure.Owing to the fact that the light management structure possesses the simple structure and excellent performance,the exploration of such a structure can be believed to be significant in fabricating the thin film-based optoelectronic devices.

Tunable absorption characteristics in multilayered structures with graphene for biosensing

Graphene derivatives,possessing strong Raman scattering and near-infrared absorption intrin-sically,have boosted many exciting biosensing applications.The tunability of the absorption characteristics,however,remains largely unexplored to date.Here,we proposed a multilayer configuration constructed by a graphene monolayer sandwiched between a buffer layer and one-dimensional photonic crystal(1DPC)to achieve tunable graphene absorption under total in-ternal reflection(TIR).It is interesting that the unique optical properties of the buffer-graphene-1DPC multilayer structure,the electromagnetically induced transparency(EIT)-like and Fano-like absorptions,can be achieved with pre-determined resonance wavelengths,and furtherly be tuned by adjusting either the structure parameters or the incident angle of light.Theoretical analyses demonstrate that such EIT-and Fano-like absorptions are due to the interference of light in the multilayer structure and the complete transmission produced by the evanescent wave resonance in the configuration.The enhanced absorptions and the huge electrical field en-hancement effect exhibit potentials for broad applications,such as photoacoustic imaging and Raman imaging.

On the monolayer dispersion behavior of Co_(3)O_(4)on HZSM-5 support:designing applicable catalysts for selective catalytic reduction of nitrogen oxides by ammonia

Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants effectively.Below the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide.However,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the samples.It is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.

Flexo-photocatalysis in centrosymmetric semiconductors

The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization field.However,it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure.Here,we demonstrate that the polarization enhanced photocatalysis(with wide spectra from ultraviolet(UV)light to visible light)can be achieved in centrosymmetric semiconductors,such asδ-MnO_(2) and TiO_(2) nanosheets integrated nanoflowers,by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced catalysis.Under ultrasonic and illumination excitation,the organic pollutants(methylene blue(MB),etc.)can be effectively degraded within 30 min with excellent stability and repeatability.Compared with photocatalysis,the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%.Moreover,the factors related to flexo-photocatalysis such as material morphology,mechanical stimuli source,and adsorption are explored to deeply understand the mechanism of flexo-photocatalysis.This work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.

First-principles Study on the Properties of CaO(100) Surface Adsorbing Carbon Dioxide

The increasing carbon dioxide emissions have a huge impact on the global environment.Carbonation reaction of CaO is regarded as a potential method to capture carbon dioxide.The density functional theory calculations have been performed to investigate the adsorption of CO_(2)on CaO(100)surface.This paper systematically studied the adsorption of CO_(2)at different adsorption sites on CaO(100)surface and the influence of adsorption angle on adsorption energy.Based on the studying of adsorption sites,adsorption energy and electronic structure of the CO_(2)/CaO(100)systems,chemical adsorption mainly happens when CO_(2)molecules are absorbed on the CaO(100)surfaces,but physical adsorption may also happen.The research found that CO_(2)molecules reacted with surface O atom through C,forming monodentate surface carbonate species and tridentate carbonate.Among them,low-coordinated monodentate ligands have a higher stability than tridentate ligands due to the shorter C–OS bond length of monodentate ligands.

具有柔性和压电性的超薄Janus纳米纤维敷料用于伤口愈合

感染性皮肤伤口的愈合常常受到许多因素的影响,包括细菌感染、过量的伤口渗出物、局部灌注不良和细胞招募不足.开发有效管理伤口和促进伤口愈合的敷料是一个巨大的挑战.因此,我们通过逐层静电纺丝技术构建了一种具有抗菌性、柔性和压电特性的超薄Janus纳米纤维敷料.敷料的亲水层由随机排列的聚己内酯/明胶纳米纤维组成,而疏水层则由Ag纳米颗粒掺杂的聚偏氟乙烯有序纤维组成.体外和体内实验研究结果表明,Janus敷料不仅可以将过量的伤口渗出物单向排出,杀死局部细菌,还可以在正常身体运动下产生动态压电信号,促进成纤维细胞的增殖和迁移、胶原蛋白的沉积、血管生成和再上皮化,从而加速小鼠伤口的快速愈合.这种智能Janus敷料将为加速伤口愈合和伤口管理提供一种新方法.

Enhancing thermoelectric performance in P-type Mg_(3)Sb_(2)-based Zintls through optimization of band gap structure and nanostructuring

P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.

碳布上生长的开裂树皮状三元金属硫化物(NiCoMnS_(4))纳米结构用于高性能水系非对称超级电容器

本论文报道了一种高性能的自支撑超级电容器电极.通过一步水热工艺和随后的简单电化学处理,在碳布上制备了具有开裂树皮形状的镍-钴-锰三元金属硫化物(NiCoMnS_(4))纳米结构.该电极在1 A g^(-1)电流密度下,可实现高达2470.4 F g^(-1)的比容量,并展现出良好的倍率性能和循环稳定性.组装的基于活性炭//NiCoMnS_(4)构型的水系非对称超级电容器的电压窗口可达1.7 V;在850.1 W kg^(-1)功率密度下,获得了68.2 W h kg^(-1)的能量密度;在4 A g^(-1)电流密度下,经过10,000次循环后,容量保持率达92.5%.该电极材料制备方法简单且具有良好的储能性能,因此本研究对开发电化学性能良好的自支撑金属硫化物电极及相关高性能水系超级电容器具有重要的参考价值.

Oxygen vacancy-engineered BaTiO_(3)nanoparticles for synergistic cancer photothermal,photodynamic,and catalytic therapy

With the rapid development of photo-responsive nanomaterials,photo-triggered therapeutic strategies such as photothermal therapy(PTT)and photodynamic therapy(PDT)have been new alternatives to current cancer therapeutic methods.Herein,we have fabricated oxygen vacancy-engineered BaTiO_(3)(BTO-Ov)nanoparticles(NPs)for near-infrared(NIR)light-triggered PTT,PDT,and catalytic therapy cooperatively for significantly improving cancer therapy.Compared to pristine BaTiO_(3)nanoparticles,BTO-Ov has stronger NIR light absorption and narrower band gap structure,which results in superior photothermal conversion and superoxide radical generation capabilities through PTT and PDT.Meanwhile,due to the existence of Ti^(3+),BTO-Ov also exhibits peroxidase(POD)-like activity to produce hydroxyl radical under tumor environment,which can be further improved under 808 nm light irradiation.Both in vitro and in vivo results demonstrate that such a multifunctional therapeutic nanoplatform can achieve a high therapeutic efficacy triggered by a single NIR light irradiation.The defect engineering strategy can be used as a general approach to fabricate multifunctional cancer therapeutic nanoplatform.

High-performance nitrogen and sulfur co-doped nanotube-like carbon anodes for sodium ion hybrid capacitors

Sodium ion hybrid capacitors are of great concern in large-scale and cost-effective electrical energy storage owing to their high energy and power densities,as well as natural abundance and wide distribution of sodium.However,it is difficult to find a well-pleasing anode material that matches the high-performance cathode materials to achieve good energy and power output for sodium ion hybrid capacitors.In this paper,nitrogen and sulfur co-doped nanotube-like carbon prepared by a simple carbonization process of high sulfur-loaded polyaniline nanotubes is introduced as the anode.The assembled sodium ion half cell based on the optimal nanotube-like carbon delivers a high reversible capacity of ~304.8 mAh/g at 0.2 A/g and an excellent rate performance of ~124.8 mAh/g at 10 A/g in a voltage window of 0.01-2.5 V(versus sodium/sodium ion).For the hybrid capacitors assembled using the optimal nanotube-like carbon as the anode and high-capacity activated carbon as the cathode,high energy densities of ~100.2 Wh/kg at 250 W/kg and ~50.69 Wh/kg at 12,500 W/kg are achieved.

Surface strain-enhanced MoS_(2)as a high-performance cathode catalyst for lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)are one of the main candidates for the next generation of energy storage systems.To improve the performance of LSBs,we herein propose the use of strained MoS_(2)(s-MoS_(2))as a catalytically active sulfur host.The introduction of strain in the MoS_(2)surface,which alters its atomic positions and expands the S-Mo-S angle,shifts the d-band center closer to the Fermi level and provides the surface with abundant and highly active catalytic sites;these enhance the catalyst's ability to adsorb lithium polysulfides(LiPS),accelerating its catalytic conversion and promoting lithium-ion transferability.Strain is generated through the synthesis of core-shell nanoparticles,using different metal sulfides as strain-inducing cores.s-MoS_(2)nanoparticles are supported on carbon nanofibers(CNF/s-MoS_(2)),and the resulting electrodes are characterized by capacities of 1290 and 657 mAh g−1 at 0.2 and 5 C,respectively,with a 0.05%capacity decay rate per cycle at 8 C during 700 cycles.Overall,this work not only provides an ingenious and effective strategy to regulate LiPS adsorption and conversion through strain engineering,but also indicates a path toward the application of strain engineering in other energy storage and conversion fields.

Phase Diffusion in Single-Walled Carbon Nanotube Josephson Transistors

We investigate electronic transport in Josephson junctions formed by individual single-walled carbon nanotubes coupled to superconducting electrodes.We observe enhanced zero-bias conductance(up to 10e2/h)and pronounced sub-harmonic gap structures in differential conductance,which arise from the multiple Andreev refl ections at superconductor/nanotube interfaces.The voltage-current characteristics of these junctions display abrupt switching from the supercurrent branch to the resistive branch,with a gate-tunable switching current ranging from 65 pA to 2.5 nA.The fi nite resistance observed on the supercurrent branch and the magnitude of the switching current are in good agreement with the classical phase diffusion model for resistively and capacitively shunted junctions.

Raindrop energy-powered autonomous wireless hyetometer based on liquid-solid contact electrification

Triboelectric nanogenerators(TENGs)can directly harvest energy via solid-liquid interface contact electrification,making them very suitable for harvesting raindrop energy and as active rainfall sensors.This technology is promising for realizing a fully self-powered system for autonomous rainfall monitoring combined with energy harvesting/sensing.Here,we report a raindrop energy-powered autonomous rainfall monitoring and wireless transmission system(R-RMS),in which a raindrop-TENG(R-TENG)array simultaneously serves as a raindrop energy harvester and rainfall sensor.At a rainfall intensity of 71 mm/min,the R-TENG array can generate an average short-circuit current,open-circuit voltage,and maximum output power of 15 pA,1800 V,and 325 pW,respectively.The collected energy can be adjusted to act as a stable 2.5 V direct-current source for the whole system by a power management circuit.Meanwhile,the R-TENG array acts as a rainfall sensor,in which the output signal can be monitored and the measured data are wirelessly transmitted.Linder a rainfall intensity of 71 mm/min,the R-RMS can be continuously powered and autonomously transmit rainfall data once every 4 min.This work has paved the way for raindrop energy-powered wireless hyetometers,which have exhibited broad prospects in unattended weather monitoring,field surveys,and the Internet of Things.

Active-Sensing Epidermal Stretchable Bioelectronic Patch for Noninvasive,Conformal,and Wireless Tendon Monitoring

Sensors capable of monitoring dynamic mechanics of tendons throughout a body in real time could bring systematic information about a human body’s physical condition,which is beneficial for avoiding muscle injury,checking hereditary muscle atrophy,and so on.However,the development of such sensors has been hindered by the requirement of superior portability,high resolution,and superb conformability.Here,we present a wearable and stretchable bioelectronic patch for detecting tendon activities.It is made up of a piezoelectric material,systematically optimized from architectures and mechanics,and exhibits a high resolution of 5:8×10^(−5)N with a linearity parameter of R^(2)=0:999.Additionally,a tendon real-time monitoring and healthcare system is established by integrating the patch with a micro controller unit(MCU),which is able to process collected data and deliver feedback for exercise evaluation.Specifically,through the patch on the ankle,we measured the maximum force on the Achilles tendon during jumping which is about 16312 N,which is much higher than that during normal walking(3208 N)and running(5909 N).This work not only provides a strategy for facile monitoring of the variation of the tendon throughout the body but also throws light on the profound comprehension of human activities.

A near-zero quiescent power breeze wake-up anemometer based on a rolling-bearing triboelectric nanogenerator

Wind sensors have always played an irreplaceable role in environmental information monitoring and are expected to operate with lower power consumption to extend service lifetime.Here,we propose a breeze wake-up anemometer(B-WA)based on a rolling-bearing triboelectric nanogenerator(RB-TENG)with extremely low static power.The B-WA consists of two RB-TENGs,a self-waking-up module(SWM),a signal processing module(SPM),and a wireless transmission unit.The two RB-TENGs are employed for system activation and wind-speed sensing.Once the ambient wind-speed exceeds 2 m/s,the wake TENG(W-TENG)and the SWM can wake up the system within 0.96 s.At the same time,the SPM starts to calculate the signal frequency from the measured TENG(M-TENG)to monitor the wind speed with a sensitivity of 9.45 Hz/(m/s).After the wind stops,the SWM can switch off the B-WA within 0.52 s to decrease the system energy loss.In quiescent on-duty mode,the operating power of the B-WA is less than 30 nW,which can greatly extend the service lifetime of the B-WA.By integrating triboelectric devices and rolling bearings,this work has realized an ultralow quiescent power and self-waked-up wireless wind-speed monitoring system,which has foreseeable applications in remote weather monitoring,IoT nodes,and so on.