Progress and Challenges Toward Effective Flexible Perovskite Solar Cells

The demand for building-integrated photovoltaics and portable energy systems based on flexible photovoltaic technology such as perovskite embedded with exceptional flexibility and a superior power-to-mass ratio is enormous.The photoactive layer,i.e.,the perovskite thin film,as a critical component of flexible perovskite solar cells(F-PSCs),still faces long-term stability issues when deformation occurs due to encountering temperature changes that also affect intrinsic rigidity.This literature investigation summarizes the main factors responsible for the rapid destruction of F-PSCs.We focus on long-term mechanical stability of F-PSCs together with the recent research protocols for improving this performance.Furthermore,we specify the progress in F-PSCs concerning precise design strategies of the functional layer to enhance the flexural endurance of perovskite films,such as internal stress engineering,grain boundary modification,self-healing strategy,and crystallization regulation.The existing challenges of oxygen-moisture stability and advanced encapsulation technologies of F-PSCs are also discussed.As concluding remarks,we propose our viewpoints on the large-scale commercial application of F-PSCs.

压电势构建的内建电场增强光催化和光电催化（英文）

科技的飞速发展和世界人口膨胀带来一系列迫在眉睫的环境问题和能源危机.光催化和光电催化为缓解这些问题提供了绿色、经济有效的途径,已经被开发用于催化降解环境中的有机污染物、二氧化碳还原、水分解制备氢气,把生物质转化为清洁燃料,以及其它反应.通常,具有合适能带位置和带隙的半导体可以吸收太阳光,形成光生电子空穴对,然后转移到光催化剂表面,引发氧化还原反应.然而,有限的太阳光利用率和光诱导电子空穴对的高复合率阻碍了它们的工业化发展.在过去几十年里,研究人员已经制备了许多复合光催化剂,用以将光吸收范围从紫外区拓宽到可见光和近红外区域,如g-C3N4,BiVO4,Fe2O3,Ag3PO4,WO3,CdS,Sn3O4等.另一方面,还通过多种改性方法促进光生电子和空穴分离,包括表面改性、金属/非金属掺杂和异质结设计等.此外,偏压有助于电子的定向传输.因此,光电催化可以通过光照和偏置电压的协同作用,进一步增强载流子的分离.然而,高效地分离光生载流子仍然是一个巨大的挑战.近年来,通过压电和铁电效应合理地构建内建电场,以有效地增强载流子分离引起了越来越多的关注.压电体(包括铁电体、压电半导体等)是一类具有非中心对称晶体结构的材料.在机械变形或外加电场作用下,它们的正负电荷中心被分离,产生压电势.压电势可以在金属-半导体接触或半导体异质结的界面处调制载流子的传输.压电材料已被广泛用于调节压电半导体器件的性能,如晶体管、太阳能电池、发光二极管和自供电纳米系统.在光催化和光电催化中,压电半导体和具有永久极化的铁电材料通过构建内建电场在增强载流子分离方面显示出巨大的潜力.本综述总结了压电半导体和铁电材料增强的压电催化(包括光电催化和光电催化)的最新进展.首先,文章介绍了压电和铁电材料的性质以及构建内建电场促进载流子分离的机理.其次,讨论了压电势构建内建电场的具体途径,包括超声波、机械刷/滑动、热应力、水流和铁电永久极化.然后,阐明了具体的潜在应用,例如污染物的降解、杀菌消毒、用于水分解产氢和有机合成.最后,文章对该领域的挑战进行了总结,对压电催化剂未来发展的前景进行了展望.

金属衬底在石墨烯化学气相沉积生长中的作用

以过渡金属为催化衬底的化学气相沉积法(Chemical Vapor Deposition,CVD)已经可以制备与机械剥离样品相媲美的石墨烯,是实现石墨烯工业应用的关键技术之一。原子尺度理论研究能够帮助我们深刻理解石墨烯生长机理,为实验现象提供合理的解释,并有可能成为将来实验设计的理论指导。本文从理论计算的角度,总结了各种金属衬底在石墨烯CVD生长过程中的各种作用与相应的机理,包括在催化碳源裂解、降低石墨烯成核密度等,催化加快石墨烯快速生长,修复石墨烯生长过程中产生的缺陷,控制外延生长石墨烯的晶格取向,以及在降温过程中石墨烯褶皱与金属表面台阶束的形成过程等。在本文最后,我们对当前石墨烯生长领域中亟需解决的理论问题进行了深入探讨与展望。

蜂窝状离子印迹壳聚糖/ZSM-5复合泡沫对U(Ⅵ)的吸附特性

工业含铀废水排放导致的放射性污染严重危害环境安全和人体健康。文中制备了蜂窝状离子印迹壳聚糖/ZSM-5(ICZ)复合泡沫,用于选择性吸附U(Ⅵ)。结果表明,不同原料配比制备的ICZ泡沫中,ICZ-2对U(Ⅵ)吸附效果最佳,是由于其兼具发达的蜂窝状结构和丰富的功能基团。与非离子印迹吸附剂比较,离子印迹吸附剂ICZ-2能选择性识别目标离子,因此具有更高的吸附容量和选择性。吸附等温线符合Langmuir模型,表明为均相单分子层吸附,吸附容量达280.09 mg/g;吸附动力学符合拟二级模型,表明化学吸附是控速步骤。ICZ-2对U(Ⅵ)的吸附以功能基配位络合为主要机理。ICZ-2吸附容量高、吸附速率快、吸附选择性好,有望用于含铀废水处理。

Recent Progress in Nanoscale Covalent Organic Frameworks for Cancer Diagnosis and Therapy

Covalent organic frameworks(COFs)as a type of porous and crystalline covalent organic polymer are built up from covalently linked and periodically arranged organic molecules.Their precise assembly,welldefined coordination network,and tunable porosity endow COFs with diverse characteristics such as low density,high crystallinity,porous structure,and large specific-surface area,as well as versatile functions and active sites that can be tuned at molecular and atomic level.These unique properties make them excellent candidate materials for biomedical applications,such as drug delivery,diagnostic imaging,and disease therapy.To realize these functions,the components,dimensions,and guest molecule loading into COFs have a great influence on their performance in various applications.In this review,we first introduce the influence of dimensions,building blocks,and synthetic conditions on the chemical stability,pore structure,and chemical interaction with guest molecules of COFs.Next,the applications of COFs in cancer diagnosis and therapy are summarized.Finally,some challenges for COFs in cancer therapy are noted and the problems to be solved in the future are proposed.

Phytoremediation of Rare Tailings-Contaminated Soil

In order to achieve the goal of circular economy and sustainable development of ecological environment,it is important to separate and recover associated elements from rare mineral resources.Compared with traditional physical and che-mical remediation methods of contaminated soil,phytoremediation is regarded as the most promising green in-situ restoration technology.The purpose of this review is to efctive alleviate the environmental problems caused by rare tailings contaminated soil through phytoremediation and realize the recovery of uranium-thorium,rare earth elements(REEs)and tantalum niobium.This review took rare tailings with uranium-thorium,REEs tantalum-niobium in China as the research object,then the background,significance,mechanisms and applcation strategies of phytoremediation were elaborated.In additon,the cases of spedies with tolerance to uranium thorium,tantalum niobium as well as REEs and their remediation mechanisms were summarized,respectively.Particularly,the typical plants represented by Bras-sica juncea,Sunflower,Phytolacca americana,Dicramopteris dichotoma,Salix SPP,etc,were very efctive in the reme-diation of rare tailings.The infuence factors of phytoremediation eficiency of tailings contaminated soil were discused.Two main factors were the mobility of heavy metals in soil(external cause)and the ennichment ability of species(inter-nal cause).Since the traditional phytoremediation also had some limitations in view of this,the work discussed some auxiliary methods(such as chelaing agents or microbial assisted restoration)to improve the effiency of phytoreme-diation.Finally,the future development of phytoremediation and potential applcation directions were explored.

Highly efficient capture of thorium ion by citric acid-modified chitosan gels from aqueous solution

A novel citric acid-modified chitosan gel(CSCA)was synthesized through a simple one-step process and was used to extract thorium ions from wastewater.The CSCA samples with varying chemical compositions were analyzed using SEM with mapping EDS,FT-IR,and static water contact angle measurements,and their adsorption behaviors were studied in detail.The results showed that the adsorption performance of CSCA improves with the increase of CA content in the sample.CSCA possesses an impressive capacity for thorium adsorption of 279.8 mg/g.Furthermore,it showed an ultra-fast adsorption rate and reached equilibrium within 30 min.In terms of recyclability,the CSCA still retained more than 86%of its initial adsorption capacity after 6 cycles of reuse.Density functional theory(DFT)analysis reveals that the good selectivity of this material towards thorium ions should be attributed to the high density of adsorption sites and strong interaction between carboxyl groups and thorium ions.This work could be beneficial in the design and synthesis of new polymer materials for extracting thorium.

Self-powered electrochemical water treatment system for pollutant degradation and bacterial inactivation based on high-efficient Co(OH)_(2)/Pt electrocatalyst

Electrochemical system with electro-Fenton reaction is an effective pathway for oxidative degradation of refractory organic pollutants for water treatment.However,the method is limited by the low catalytic efficiency and high electrical cost in practical applications.This work presents a self-powered and high-efficient electrochemical system for water treatment including pollutant degradation and bacterial inactivation,which is composed of a self-powered triboelectric nanogenerator(TENG)converting mechanical energy into electrical energy,a power management circuit integrated with a supercapacitor to store the harvesting electrical energy temporarily,and an electrochemical setup integrated with two-dimentional Co(OH)_(2)/Pt nanosheet as electrocatalyst.The nanocatalyst,ultrafine Pt nanoparticles(Pt NPs)loaded on Co(OH)_(2) nanosheet(Co(OH)_(2)/Pt),is synthesized by a facile one step hydrothermal reaction without any surfactant,which can improve H_(2)O_(2)and hydroxyl radical production via redox reaction.This self-powered electrocatalytic system is able to degrade nearly 100%of organic pollutant within 100 min,and efficiently kill bacteria.This work shows great potential to develop high-efficient and self-powered electrochemical water treatment system through integrating TENG and nanocatalyst.

Recent advances of implantable systems and devices in cancer therapy and sensing

Malignant tumors have the capability to metastasize and colonize,meaning that they can spread to other organs and tissues,distributing metastatic focus and are hard to target.Although significant advances have been made in cancer treatment,it remains one of the leading causes of death around the globe.In recent years,new-emerging implantable systems and devices have been developed to tackle the challenge of metastatic tumors.In this review,implantable systems for suppressing tumors and preventing tumor recurrence are reported.In particular,we emphasize the responsive drug delivery systems and the external field assisted catalytic therapy for tumor treatment,as well as implantable biosensors for tumor microenvironment monitoring.We also conclude the open challenges and future perspectives of implantable systems and devices for cancer therapy and sensing.

Strain Effects in Graphene and Graphene Nanoribbons:The Underlying Mechanism

A tight-binding analytic framework is combined with first-principles calculations to reveal the mechanism underlying the strain effects on electronic structures of graphene and graphene nanoribbons(GNRs).It provides a unified and precise formulation of the strain effects under various circumstances-including the shift of the Fermi(Dirac)points,the change in band gap of armchair GNRs with uniaxial strain in a zigzag pattern and its insensitivity to shear strain,and the variation of the k-range of edge states in zigzag GNRs under uniaxial and shear strains which determine the gap behavior via the spin polarization interaction.

Synthesis of graphene oxide nanoribbons/chitosan composite membranes for the removal of uranium from aqueous solutions

In this study,a graphene oxide nanoribbons/chitosan(GONRs/CTS)composite membrane was successfully prepared by encapsulating CTS into GONRs,which were unzipped from multi-walled carbon nanotubes.The GONRs/CTS composite membrane so prepared was characterized using scanning electron microscopy,X-Ray diffraction and Fourier transform infrared spectroscopy.The effects of the experimental conditions such as the pH(2-7),adsorbent dosage(10-50mg),experimental time(5min-32h),uranium concentration(25-300mg·L^-1),experimental temperature(298K-328K)on the adsorption properties of the composite membrane for the removaal of U(VI)were investigated.The results showed that the U(VI)adsorption process of the GONRs/CTS composite membrane was pH-dependent,rapid,spontaneous and endothermic.The adsorption process followed the pseudosecondary kinetics and Langmuir models.The maximum U(VI)adsorption capacity of the GONRs/CTS composite membrane was calculated to be 320mg·g^-1.Hence,the GONRs/CTS composite membrane prepared in this study was found to be suitable for separating and recovering uranium from wastewater.

Association of cancer prevention awareness with liver cancer screening participation rates among a high-risk population:results from rural Anhui Province

To the Editor:Liver cancer(LC)is one of the most commonly diagnosed cancers and the leading cause of cancer mortality in the world,with approximately 905,677 new cases and 830,180 deaths in 2020.[1]Clearly,the huge burden exerted by LC highlights the need to effectively decrease the incidence and mortality of LC.Unfortunately,survival rates of LC have been maintained at a low level to date.A recent meta-analysis showed that the age-standardized 5-year LC survival rate in China was 10.1%in 2003 to 2005 and 12.1%in 2012 to 2015.[2]The poor prognosis of LC may be partly attributed to the advanced stages once diagnosed for most patients,suggesting that early detection,early diagnosed,and early treatment of LC are warranted.[3]

Phosphonate-Decorated Covalent Organic Frameworks for Actinide Extraction: A Breakthrough Under Highly Acidic Conditions

Although solid-phase extraction is a useful approach for metal ion separation from aqueous solutions,existing sorbents suffer from low extraction effici-encies and/or instability when in contact with strong acidic media.We report here the first study on rational design and fabrication of phosphonate-decorated covalent organic frameworks,COF-IHEP1 and COF-IHEP2,for efficient and selective extraction of of uranium(VI)[U(VI)]and plutonium(IV)[Pu(IV)]from highly acidic solutions.

Effects of solvent,supersaturation ratio and silica template on morphology and polymorph evolution of vanillin during swift cooling crystallization

Swift cooling crystallization of vanillin was investigated in water,ethanol,isopropanol and ethyl acetate.Morphology and polymorph evolution of vanillin were discussed in terms of solvent,supersaturation ratio and silica template.PXRD,DSC,FTIR and microscope were used to identify polymorphs of vanillin.Results showed that the nucleated polymorphs of vanillin depended largely on the solvent,supersaturation ratio and silica template.Low supersaturation ratios favor the nucleation of stable form I in water,and high supersaturation ratio exceeds 7 generating 100%metastable form II.However,if the supersaturation ratio is too high(S>8),liquid-liquid phase separation will occur,and no crystals could be obtained.In other solvents such as ethanol,isopropanol and ethyl acetate,only form I was obtained.However,it should be noted that the morphology of form I prepared in ethanol,isopropanol and ethyl acetate is distinct from that obtained in water,the former is flake-like and the latter is rod-like.The nucleation of vanillin from different solution was also studied with the presence of SiO_(2),SiO_(2)-NH_(2)and SiO_(2)−COOH templates,which did not change the nucleated polymorph of vanillin,but changed the nucleation and growth rate of stable form I.

Adsorption removal of sulfamethoxazole from water using UiO-66 and UiO-66-BC composites

The adsorption removal of anti-inflammatory drugs from water by diverse materials has drawn great attention.This study investigated the adsorption of sulfamethoxazole(SMX)by two types of materials,UiO-66 and UiO-66-BC composites.Highly porous MOF composites with functional groups were synthesized by combining UiO-66 with corncob-based biochar at different molar ratios.SEM results showed that macroporosity of UiO-66-BC composites was increased by increasing the ratio of biochar.It was found that UiO-66-BC composites displayed highly improved adsorption performance of SMX relative to pristine UiO-66.UiO-66-BC(5%)had the highest SMX adsorption capacity,about 2.4 times those of pristine UiO-66.It was the high surface area of UiO-66 and redundant functional groups of biochar that increased the adsorption performance of composites.Moreover,UiO-66-BC can be reused and displayed the competitive adsorption efficiency after successive adsorption,which made it a potential adsorbent for the removal of SMX from water.

Association between population migration and epidemic control of coronavirus disease 2019

Dear Editor,In January 2020,a widespread outbreak of coronavirus disease 2019(COVID-19)occurred after the beginning of the largest annual migration in China,which is known as the Spring Festival migration.Starting in January 20,2020,the Chinese government took a series of unprecedented measures to contain the spread of COVID-19.Because of the role of Wuhan as a central transportation hub.

Movement of Dirac points and band gaps in graphyne under rotating strain

The introduction of lattice anisotropy causes Dirac cones to shift in response to the applied strain, leaving a pseudogap at the original Dirac points. Here, a group-theory analysis is combined with first-principles calculations to reveal the movement characteristics of Dirac points and band gaps in various graphynes under rotating uniaxial and shear strains. Graphene, where linear effects dominate, is different from α-,β-, and γ-graphynes, which generate strong nonlinear responses due to their bendable acetylenic linkages. However, the linear components of the electronic response, which are essential in determining material performance such as intrinsic carrier mobility due to electron-phonon coupling, can be readily separated, and are well described by a unified theory. The movement of the Dirac points in α-graphyne is circular under a rotating strain, and the pseudogap opening is isotropic with a magnitude of only 2% that in graphene. In comparison, the movement in β-graphyne is elliptical and the center is displaced from the origin. For γ-graphyne, three branches of gaps change with the applied strains with a sine/cosine dependence on the strain angle. The developed methodology is useful in determining the electronic response to various strains of Dirac materials and two-dimensional semiconductors,

Electrochemical deposition of uranium oxide with an electrocatalytically active electrode using double potential step technique

The development of effective uranium-removal techniques is of great significance to the environment and human health.In this work,a double potential step technique(DPST)was applied to remove U(VI)from uranium-containing wastewater using a carbon felt electrode modified by graphene oxide/phytic acid composite(GO-PA@CF).The application of DPST can inhibit water splitting and prevent GO-PA from adsorbing other interfering ions in wastewater.The GO-PA composite can effectively accelerate the electrochemical reduction rate of U(VI),which significantly improved the electrochemical deposition rate of uranium oxide.As a result,the maximum removal efficiency and maximum removal capacity of GOPA@CF electrode reached 98.7%and 1149.3 mg/g,respectively.The removal efficiency remained 97.2%after five cycles of reuse.Moreover,the removal efficiency of GO-PA@CF electrode can reach more than 70%in simulated wastewater.

Cocrystals of carbamazepine:Structure,mechanical properties,fluorescence properties,solubility,and dissolution rate

Carbamazepine(CBZ)is an anticonvulsant with very low water solubility,presenting as a white crystalline powder with poor mechanical properties and is hard to bend.To enhance CBZ's physicochemical properties,such as water solubility and mechanical properties,we selected six cocrystal coformers(CCFs):nicotinamide(NIC),benzamide(BZM),salicylic acid(SCA),fumaric acid(FMA),trimesic acid(TMA),and hesperetin(HPE).Six CBZ cocrystals were successfully prepared using the solution method.Fourier transform infrared spectroscopy(FT-IR),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC),and single crystal X-ray diffraction(SCXRD)were used to characterize the crystal structures and gain comprehensive insights into the six cocrystals.The mechanical,fluorescence,and solubility properties of the six cocrystals were tested.The results reveal that most of the prepared cocrystals exhibit improved water solubility and mechanical properties when compared to CBZ.Among them,the dissolution rate of cocrystals excluded from CBZ-HPE has increased by an average of 3 or 4 times compared to CBZ,while CBZ-HPE exhibits superior mechanical properties.Moreover,all six cocrystals possess better fluorescence performance than CBZ.We thoroughly evaluated the mechanical properties of the cocrystals through both experimental and theoretical approaches.This work provides a new direction for studying drug cocrystals to improve the physicochemical properties of drugs.