Miniaturized electrochemical sensors and their point-of-care applications

Most of the current analytical methods depend largely on laboratory-based analytical techniques that require expensive and bullky equipment,potentially incur costly testing,and involve lengthy detection processes.With increasing requirements for point-of-care testing(POCT),more attention has been paid to miniaturized analytical devices.Miniaturized electrochemical(MEC)sensors,including different material-based MEC sensors(such as DNA-,paper-,and screen electrode-based),have been in strong demand in analytical science due to their easy operation,portability,high sensitivity,as well as their short analysis time.They have been applied for the detection of trace amounts of target through measuring changes in electrochemical signal,such as current,voltage,potential,or impedance,due to the oxidation/reduction of chemical/biological molecules with the help of electrodes and electrochemical units.MEC sensors present great potential for the detection of targets including small organic molecules,metal ions,and biomolecules.In recent years,MEC sensors have been broadly applied to POCT in various fields,including health care,food safety,and environmental monitoring,owing to the excellent advantages of electrochemical(EC)technologies.This review summarized the state-of-the-art advancements on various types of MEC sensors and their applications in POCT.Furthermore,the future perspectives,opportunities,and challenges in this field are also discussed.     

Machine Learning towards Screening Solid-state Lithium Ion Conductors

Machine learning is an emerging method to discover new materials with specific characteristics.An unsupervised machine learning research is highlighted to discover new potential lithium ionic conductors by screening and clustering lithium compounds,providing inspirations for the development of solid-state electrolytes and practical batteries.     

等浓度的氯化铵和硫酸铵溶液哪个pH高

有中学化学参考资料题:0.10 mol/L的NH4Cl和(NH4)2SO4溶液哪个pH值高?这似乎是个中学生可做的简单题目,仔细考虑不是如此.如果简单地认为盐酸和硫酸都是强酸,而硫酸是二元酸,硫酸铵溶液中铵盐浓度为0.20 mol/L,那么NH4Cl溶液pH高,那是不妥的.硫酸是二元酸,第一个氢离子能完全电离,第二个氢离子部分电离,如此考虑情况怎么样呢?是不是答案发生变化?这要通过计算来说明.     

Surface defect-rich ceria quantum dots anchored on sulfur-doped carbon nitride nanotubes with enhanced charge separation for solar hydrogen production

Designing defect-engineered semiconductor heterojunctions can effectively promote the charge carrier separation.Herein,novel ceria(CeO2) quantum dots(QDs) decorated sulfur-doped carbon nitride nanotubes(SCN NTs) were synthesized via a thermal polycondensation coupled in situ depositionprecipitation method without use of template or surfactant.The structure and morphology studies indicate that ultrafine CeO2 QDs are well distributed inside and outside of SCN NTs offering highly dispersed active sites and a large contact interface between two components.This leads to the promoted formation of rich Ce³⁺ ion and oxygen vacancies as confirmed by XPS.The photocatalytic performance can be facilely modulated by the content of CeO2 QDs introduced in SCN matrix while bare CeO2 does not show activity of hydrogen production.The optimal catalyst with 10% of CeO2 loading yields a hydrogen evolution rate of 2923.8 μmol h-1 g-1 under visible light,remarkably higher than that of bare SCN and their physical mixtures.Further studies reveal that the abundant surface defects and the created 0 D/1 D junctions play a critical role in improving the separation and transfer of charge carriers,leading to superior solar hydrogen production and good stability.     

Superfast and solvent-free core-shell assembly of sulfur/carbon active particles by hail-inspired nanostorm technology for high-energy-density Li-S batteries

The demand on low-carbon emission fabrication technologies for energy storage materials is increasing dramatically with the global interest on carbon neutrality.As a promising active material for metal-sulfur batteries,sulfur is of great interest due to its high-energy-density and abundance.However,there is a lack of industry-friendly and low-carbon fabrication strategies for high-performance sulfur-based active particles,which,however,is in critical need by their practical success.Herein,based on a hail-inspired sulfur nano-storm(HSN)technology developed in our lab,we report an energy-saving,solvent-free strategy for producing core-shell sulfur/carbon electrode particles(CNT@AC-S)in minutes.The fabrication of the CNT@AC-S electrode particles only involves low-cost sulfur blocks,commercial carbon nanotubes(CNT)and activated carbon(AC)micro-particles with high specific surface area.Based on the above core-shell CNT@AC-S particles,sulfur cathode with a high sulfur-loading of 9.2 mg cm^-2 delivers a stable area capacity of 6.6 mAh cm^-2 over 100 cycles.Furthermore,even for sulfur cathode with a super-high sulfur content(72 wt%over the whole electrode),it still delivers a high area capacity of 9 mAh cm^-2 over50 cycles in a quasi-lean electrolyte condition.In a nutshell,this study brings a green and industryfriendly fabrication strategy for cost-effective production of rationally designed S-rich electrode particles.     

Unraveling the stabilization mechanism of solid electrolyte interface on ZnSe by rGO in sodium ion battery

Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.     

CXN天然沸石的研究2: 吸附性质

采用N~2,NH~3,CO~2,乙烯,丙烯,水,甲醇,乙醇,丙醇等作为吸附剂,研究了由我国CXN天然沸石改性制得的H-STI和Na-STI沸石的吸附性质,H-STI和Na-STI沸石的BET表面积及微孔孔体积约为420m^2/g和0.20m^3/g。根据NH~3和CO~2在H-STI沸石上的吸附等温线计算得到它们的吸附热分别为44.8和26.5kJ/mol。乙烯,丙烯,甲醇,乙醇,丙醇等在Na-STI沸石上的吸附等温线表明该沸石对有机分子的吸附具有链长选择性。在低分压下水相对于甲醇的吸附量表明沸石具有一定的疏水性质。     

常温常湿条件下Au/MeO~x催化剂上CO氧化性能

利用共沉淀法制备了Au/MeO~x催化剂(Me=Al,Co,Cr,Cu,Fe,Mn,Ni,Zn)。在常温常湿条件下,考察了不同氧化物负载的金基催化剂的CO氧化性能。结果表明,氧化物种类对催化剂的活性和稳定性均有较大的影响。Cu,Mn,Cr等氧化物负载的金基催化剂的活性较差,而Zn,Fe,Co,Ni,Al等金属氧化物负载的金基催化剂可将CO完全氧化,又具有一定的稳定性,在相同反应条件下,CO完全转化时的稳定性顺序为Au/ZnO>Au/α-Fe~2O~3>Au/Co~3O~4>Au/γ-Al~2O~3≈Au/NiO。还发现水对Au/MnO~x催化剂的活性和稳定性有负作用,而对180℃焙烧制备的Au/ZnO-180催化剂的活性和稳定性均有明显的湿度增强作用。     

Enhanced efficiency and stability in Sn-based perovskite solar cells with secondary crystallization growth

The conversion efficiencies reported for Tin(Sn)halide-based perovskite solar cells(PSCs)fall a large gap behind those of lead halide-based PSCs,mainly because of poor film quality of the former.Here we report an efficient strategy based on a simple secondary crystallization growth(SCG)technique to improve film quality for tin halide-based PSCs by applying a series of functional amine chlorides on the perovskite surface.They were discovered to enhance the film crystallinity and suppress the oxidation of Sn²⁺remarkably,hence reduce trap state density and non-irradiative recombination in the absorber films.Furthermore,the SCG film holds the band levels matching better with carrier transport layers and herein favoring charge extraction at the device interfaces.Consequently,a champion device efficiency of 8.07% was achieved alo ng with significant enhancements in VOC and JSC,in contrast to 5.35% of the control device value.Moreover,the SCG film-based devices also exhibit superior stability comparing with the control one.This work explicitly paves a novel and general strategy for developing high performance lead-free PSCs.     

Boost oxygen reduction reaction performance by tuning the active sites in Fe-N-P-C catalysts

Cost-effective atomically dispersed Fe-N-P-C complex catalysts are promising to catalyze the oxygen reduction reaction(ORR)and replace Pt catalysts in fuel cells and metal-air batteries.However,it remains a challenge to increase the number of atomically dispersed active sites on these catalysts.Here we report a highly efficient impregnation-pyrolysis method to prepare effective ORR electrocatalysts with large amount of atomically dispersed Fe active sites from biomass.Two types of active catalyst centers were identified,namely atomically dispersed Fe sites and Fe_xP particles.The ORR rate of the atomically dispersed Fe sites is three orders of magnitude higher than it of Fe_xP particles.A linear correlation between the amount of the atomically dispersed Fe and the ORR activity was obtained,revealing the major contribution of the atomically dispersed Fe to the ORR activity.The number of atomically dispersed Fe increases as the Fe loading increased and reaching the maximum at 1.86 wt%Fe,resulting in the maximum ORR rate.Optimized Fe-N-P-C complex catalyst was used as the cathode catalyst in a homemade Zn-air battery and good performance of an energy density of 771 Wh kgZn^-1,a power density of 92.9 m W cm^-2 at 137 m A cm^-2 and an excellent durability were exhibited.     

基于苝二酰亚胺类非富勒烯受体共混体系凝聚态结构调控

非富勒烯太阳能电池具有给受体能级可调、吸收范围宽及可溶液加工等优势,已经成为太阳能电池领域发展趋势。在高性能材料开发及器件结构优化的推动下,能量转换效率已经突破11%。其中,苝二酰亚胺(PDI)类分子价格低廉且具有良好的稳定性及较高的电子迁移率,已经发展成为重要的非富勒烯受体材料。然而,PDI类材料刚性稠环结构使得分子间具有强烈的π-π相互作用(受体-受体分子间及给体-受体分子间),导致共混体系相分离尺寸可控性差,给受体分子间共混程度难于调控,从而发生严重的成对以及非成对电荷复合。本文从分子间作用力入手(溶剂-溶质、给体-受体分子间作用力)详述了非富勒烯共混体系相分离结构、相区尺寸及共混相含量调节的相关原理及方法。研究表明基于PDI共混体系,固-液相分离及分子扩散能力是决定相分离结构的本质因素,通过调控给受体比例及热退火温度实现了孤岛及互穿网络结构的构筑。同时,通过平衡受体分子间π-π作用及给受体间电荷转移,实现了低相容性及高相容性共混体系相区尺寸的可控调节。在此基础上,利用添加剂手段通过调节溶剂与溶质分子间的溶度参数差值,实现了薄膜内共混相的可控调节,并针对具有不同相容性共混体系给出了添加剂的选择原则。     

Progress in Molecular Dynamics and Hansen Solubility Parameters of Low Molecular Weight Gels北大核心CSCD

Recently,the use of computational methods such as Molecular Dynamics（MD）simulations and Hansen Solubility Parameters （HSPs）to study the behavior of small molecule gelators has attracted much attention. MD simulation is a computational method based on classical mechanics and is one of the preferred techniques for understanding the process of small molecule gelators. The MD simulation can more accurately analyze the gelation trend or assembly behavior of small molecule gelators,dynamically and graphically display the self-assembly process,effectively reveal the relationship between the structure of small molecule gelators and related gelation behavior,and quantitatively analyze non-covalent bond interactions such as hydrogen bonds,π-π stacking,van der Waals interactions,ionic bonding and solvophobic interactions. By performing molecular dynamics simulations on known gelators/non-gelators,parameters related to gelation behavior in the simulated data are extracted,and the linear correlation is measured by fitting the Pearson correlation coefficient to finally predict the gelation behavior of a certain class of small molecules. On the other hand,the empirical model developed according to the HSPs is the most representative,which consists of the energy of dispersion interaction（δd）,the energy of polar interaction（δp）and H-bonding energy（δh ）between molecules. These three parts determine the coordinate point of the three-dimensional space（Hansen space）. According to the range of the point,it can be determined whether the organic small molecule can form a gel in a specific solvent. In this paper,representative works published recently in the field of organic small molecule gels by using MD simulations and empirical models are reviewed. Some comments on the assembly behavior of gelators,the regulation and prediction of non-covalent bond interactions on gelation ability are made. © 2022, Science Press (China). All rights reserved.     

Research Progress of Regulation of Driving Forces in Short Peptide Supramolecular Self-Assembly北大核心CSCD

Some short peptides can spontaneously self-assemble into various nanostructures via the synergistic driving forces of non-covalent interactions. These non-covalent interactions,including electrostatic interaction,hydrogen bonding,aromatic interactions and other non-covalent interactions,are usually highly coupled together. Through rational sequence design and proper modification of short peptide molecules,the driving forces could be regulated purposively,and the nanostructures and morphologies of the self-assemblies could be controlled accordingly,and thus so as to achieve the fabrication of peptide-based supramolecular biomaterials and develop their functions. In this paper,the effects of hydrogen bonding,π-π stacking, electrostatic interaction,hydrophobic interaction,metal ion coordination and chiral center on the self-assembly behavior of peptide self-assembly have been reviewed. The driving force regulation strategies, including sequence design,pH and concentration adjustment and metal ion coordination,and the resulted nanostructures have also been discussed. We also make the outlooks on the development of peptide-based supramolecular biomaterials with specific functions in biomedicines and biocatalysis. © 2022, Science Press (China). All rights reserved.     

3, 4-二乙氧基苯甲酸与2, 2'-联吡啶三元稀土配合物的合成、晶体结构及热化学性质

本文合成了两种三元稀土配合物[Ln（3, 4-DEOBA）₃DIPY]₂DIPY（Ln=Er（1）,Gd（2）;3, 4-DEOBA：3, 4-二乙氧基苯甲酸根;DIPY：2, 2'-联吡啶）,通过元素分析,红外光谱和单晶X-射线衍射对配合物进行表征和分析。实验表明两种配合物是同种晶型的双核分子,相邻结构单元通过π-π作用形成一维链状和二维层状的超分子结构。同时还利用同步热分析与傅里叶变换红外联用（TG-FTIR）技术对配合物的热分解机理进行分析。通过差示扫描量热（DSC）技术,测得两种配合物的摩尔热容,将所得配合物的摩尔热容与折合温度进行多项式拟合,并根据热力学方程,计算得到了两种配合物的舒平摩尔热容和热力学函数值。     

官能团化的手性联芳基单齿膦配体在不对称均相金催化反应中的应用

自2005年以来, 不对称均相金催化反应研究取得了显著的进展, 并在有机合成中得到了广泛应用. 近年来, 官能团化的联芳基单齿膦配体在金催化反应中显露头角, 为不对称金催化反应提供了新的发展思路. 本文综合评述了这一领域的研究进展, 着重介绍了近年来利用这类配体实现的金催化不对称反应及反应过程中配体与底物间相互作用.     

卤代芳香族羧酸与含氮配体合成镧系配合物的结构、热化学和荧光性质（英文）

采用室温溶液挥发法合成了五种结构新颖的镧系配合物,其结构通式为[Ln(2,4-DFBA)₃(phen)]₂ (Ln=Sm 1, Eu2, Er 3, 2,4-DFBA为2,4二氟苯甲酸的简写,phen为1,10-菲啰啉的简写),[Ln(2-Cl-6-FBA)₂(terpy)(NO₃)(H₂O)]₂ (Ln=Tb4, Dy 5, 2-Cl-6-FBA为2-氯-6-氟苯甲酸的简写, terpy为2,2’:6’2’’-三联吡啶的简写)。五个配合物可以分为两个系列,使用不同的镧系离子作为中心离子。通过X射线单晶分析,5种配合物均属于单斜晶系,空间群为P21/n。配合物1,2和配合物3虽然具有相同的分子通式,但配位方式明显不同,形成了前者为9配位的松饼型,后者是8配位的双帽三棱柱几何构型。二维面状超分子结构的形成方式也明显不同,区别在于配合物1和2通过微弱的π-π堆积作用形成。配合物4和5是同构的,结构中引入了硝酸根离子较为有趣,通过C―H···F氢键和π-π堆积作...     

八电子Pd4四面体团簇的电子结构稳定性分析

基于理论计算,我们报道了T_d对称性的[Pd₄(μ₃-SbH₃)₄(SbH₃)₄]团簇及一系列类似物的结构与成键。成键分析表明：每个Pd原子都是sp³杂化,其10个价电子与四个配体提供的8个价电子,满足18电子规则。并且,每个Pd原子与四个桥连的SbH₃配体可以形成四个离域的四中心两电子超级σ键或八中心两电子键。一方面,根据超原子网络模型,这个钯团簇可以描述成四个2电子的超原子网络。另一方面,凝胶模型表明,它可以合理化的作为电子组态是1S²1P⁶的8电子超原子。与此同时,d¹⁰…d¹⁰闭壳层相互作用在稳定Pd₄四面体结构中起到了关键性的作用。密度泛函理论计算表明：T_d对称性[Pd₄(μ₃-SbH₃)₄(SbH₃)₄]团簇表现出高度稳定性,具有充满的电子壳层,大的HOMO-LUMO带隙(2.84 eV)以及负的核独立化学位移(NICS)值。此外,基于[Pd₄(μ₃-SbH₃)₄(SbH₃)₄]结构与成键模式,我们设计了一系列稳定的类似物,其有可能被实验合成出来。     

B972-PFD:一种高精度的色散校正密度泛函方法

发现一种与球原子经验色散模型SAM深度契合的杂化泛函B972,组合成高精度的色散校正密度泛函B972-PFD。采用S66、S66x8和S22标准数据集以及大气氢键团簇、Adenine-Thymine的π…π堆叠、Watson-Crick氢键复合物和甲烷结合(H_2O)_(20)水簇等体系测试了B972-PFD的性能。测试结果显示:对于S66数据集B972-PFD方法的精度与Head-Gordon研究组的三个新泛函ωB97X-V、B97M-V和ωB97M-V处于同一水平,相对于CCSD(T)/CBS金质标准,结合能的RMSD小于1 k J?mol~(-1);在其它数据集的测试中,B972-PFD方法也表现出很好的计算精度。通过研究基函数效应,我们推荐Pople的6-311++G(2d,p)作为B972-PFD方法的最优性价比基组。     

确定分子中离域π键πnm的方法

A method for obtaining the delocalized π bonds π_n^m in a molecule has been discussed in this paper, and the delocalized π bonds π_n^m in linear, bent, planar trigonal, single cyclic conjugated, and polycyclic conjugated molecules have been studied. The reasons of π₃⁴ in NO₂ and 2π₃² in C₃ molecules have been proposed. The delocalized π bonds 2π₁₈¹⁸ in cyclo[18] carbon are analyzed.     

碰撞能对K(2S)+HF(X1Σ+)→KF(X1Σ+)+H(2S)反应的影响

基于Sayós等构建的基态势能面, 运用准经典轨线方法对原子-分子反应K(²S)+HF(X¹∑⁺)→KF(X¹∑⁺)+ H(²S)的立体动力学性质进行了研究. 计算了该反应的极化微分反应截面、 两矢量k?j'相关分布函数P(θ_r)、 三矢量k?k'?j'相关分布函数P(?_r)和空间分布函数P(θ_r,?_r). 结果表明, 产物KF的转动角动量j′不仅在垂直于反应物相对速度矢量k的方向上有强烈的取向效应, 而且还定向于y轴的负方向, 转动角动量j′敏感地依赖于碰撞能.