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.     

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.     

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。     

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。     

Regulation of carbon distribution to construct high-sulfur-content cathode in lithium-sulfur batteries

Lithium-sulfur(Li-S)battery is regarded as one of the most promising next-generation energy storage systems due to the ultra-high theoretical energy density of 2600 Wh kg^-1.To address the insulation nature of sulfur,nanocarbon composition is essential to afford acceptable cycling capacity but inevitably sacrifices the actual energy density under working conditions.Therefore,rational structural design of the carbon/sulfur composite cathode is of great significance to realize satisfactory electrochemical performances with limited carbon content.Herein,the cathode carbon distribution is rationally regulated to construct high-sulfur-content and high-performance Li-S batteries.Concretely,a double-layer carbon(DLC)cathode is prepared by fabricating a surface carbon layer on the carbon/sulfur composite.The surface carbon layer not only provides more electrochemically active surfaces,but also blocks the polysulfide shuttle.Consequently,the DLC configuration with an increased sulfur content by nearly 10 wt%renders an initial areal capacity of 3.40 mAh cm^-2 and capacity retention of 83.8%during 50 cycles,which is about two times than that of the low-sulfur-content cathode.The strategy of carbon distribution regulation affords an effective pathway to construct advanced high-sulfur-content cathodes for practical high-energy-density Li-S batteries.     

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.     

Confined Ni-In intermetallic alloy nanocatalyst with excellent coking resistance for methane dry reforming

Carbon dioxide and methane are two main greenhouse gases which are contributed to serious global warming.Fortunately,dry reforming of methane(DRM),a very important reaction developed decades ago,can convert these two major greenhouse gases into value-added syngas or hydrogen.The main problem retarding its industrialization is the seriously coking formation upon the nickel-based catalysts.Herein,a series of confined indium-nickel(In-Ni)intermetallic alloy nanocatalysts(In_xNi@SiO₂)have been prepared and displayed superior coking resistance for DRM reaction.The sample containing 0.5 wt.%of In loading(In_0.5Ni@SiO₂)shows the best balance of carbon deposition resistance and DRM reactivity even after 430 h long term stability test.The boosted carbon resistance can be ascribed to the confinement of core–shell structure and to the transfer of electrons from Indium to Nickel in In-Ni intermetallic alloys due to the smaller electronegativity of In.Both the silica shell and the increase of electron cloud density on metallic Ni can weaken the ability of Ni to activate C–H bond and decrease the deep cracking process of methane.The reaction over the confined InNi intermetallic alloy nanocatalyst was conformed to the Langmuir-Hinshelwood(L-H)mechanism revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy(in-situ DRIFTS).This work provides a guidance to design high performance coking resistance catalysts for methane dry reforming to efficiently utilize these two main greenhouse gases.     

配位聚合物[Cd2(BDC)2(obix)2]·H2O的合成、晶体结构和荧光性质

用水热合成方法得到1个新的配位聚合物[Cd2(BDC)2(obix)2]·H2O(H2BDC=对苯二甲酸,obix=1,2-(二亚甲基)二咪唑).配合物晶体属三斜晶系,P1空间群.晶体结构表明:镉原子与3个对苯二甲酸上的5个氧原子,2个1,2-(二亚甲基)二咪唑中的2个氮原子配位形成扭曲的五角双锥配位构型.2个Cd(Ⅱ)原子通过两个羧基桥联形成一个双核Cd2单元,再通过配体连接成二维层状结构,层与层之间通过C-H…O氢键和弱的π-π相互作用形成三维超分子结构.室温下配合物具有较强的荧光发射光谱.     

Zinc coordination polymers with rigid dicarboxylates and semirigid 3,5-bis(imidazole-1-yl) pyridine: syntheses,structural topologies,and luminescent properties

Two metal coordination polymers, {[Zn(bpdc)(bip)]·2H₂O}_n (1) and [Zn(tdc)(bip)] (2) [H₂bpdc?=?biphenyl-4,4’-dicarboxylate, H₂tdc?=?thiophene-2,5-dicarboxylate, bip?=?3,5-bis(imidazole-1-yl)pyridine], have been synthesized and characterized by IR, elemental analysis, XRD, and X-ray single-crystal diffraction. In 1, bpdc and bip link Zn(II) ions into a corrugated 2D layer. The corrugated 2D layers polycatenate each other, yielding a 2D→3D polycatenation net. In 2, dinuclear Zn(II) units are formed by bip and further connected by tdc to construct a 2D 3-connected framework. The luminescent properties of 1 and 2 are investigated in the solid state at room temperature.     

以3, 5-二甲基-1-羧甲基-4-吡唑甲酸为配体的两个锌的配合物的合成、晶体结构和荧光性能

以3, 5-二甲基-1-羧甲基-4-吡唑甲酸和4, 4'-联吡啶为配体, 合成了1个单核锌(II)配合物[Zn(4,4'-bpy)(Hcmdpca)₂(H₂O)₃]·2H₂O (1)和1个锌(II)的一维配位聚合物[Zn(4, 4'-bpy)(Hcmdpca)₂(H₂O)]·3H₂O (2)(H₂cmdpca=3, 5-二甲基-1-羧甲基-4-吡唑甲酸;4, 4'-bpy=4, 4'-联吡啶), 并用元素分析、红外光谱、X-射线单晶衍射结构分析、热重分析等对其进行了表征。配合物1和2都属于单斜晶系, 空间群为P2₁/c。配合物1的锌离子都位于一个畸变的八面体构型中。配合物1中的独立结构单元间通过分子间氢键作用构成一个三维的超分子结构。而在2中, 锌离子位于一个畸变的四方锥构型中, 每个4, 4'-联吡啶分子桥联2个相邻的 锌(II)离子, 形成一个一维链;这些一维链和水分子通过分子间氢键进一步形成一个三维的结构。此外还考察了1和2的热稳定性和固体荧光性质。     

Synthesis,structure and luminescent properties of Cd(II) and Zn(II) complexes constructed from 3,5-dimethyl-2, 6-pyrazinedicarboxylic acid

[Cd₂(phen)₂(DPZDA)₂(H₂O)₂] · 8H₂O (1) and [Zn(phen)(DPZDA)(H₂O)] · 2H₂O (2) have been synthesized by reaction of Cd(NO₃)₂/Zn(NO₃)₂ with phen and DPZDA (where phen = 1,10-phenanthroline, H₂DPZDA = 3,5-dimethyl-2,6-pyrazinedicarboxylic acid) in aqueous ethanol solution. Elemental analysis, IR spectra, thermal analyses and X-ray single crystal diffraction were carried out to determine the composition and crystal structure of 1 and 2. In 1, a 2D supramolecular network containing a novel metal-water decamer were formed by hydrogen bonds. In 2, a 2D supramolecular structure was constructed from hydrogen bonds and π·· · π interactions. Moreover, 1 and 2 displayed photoluminescent properties in the blue range at room temperature.     

基于柠康酸构筑的三个配合物的合成、结构与性能

在水热条件下,制备出3个配位聚合物,即{[Zn（ca）（iimb）]·0.75H₂O}_n（1）,{[Cd（ca）（iimb）（H₂O）]·0.75H₂O}_n（2）和{[Zn（ca）（bpe）_0.5（H₂O）]·H₂O}_n（3）（H₂ca=柠康酸,iimb=1-（1-咪唑基）-4-（咪唑基-1''-甲基）苯,bpe=1,2-二（4-吡啶基）乙烯）,并通过单晶X射线衍射、红外光谱和元素分析进行结构表征。配合物1是含有一维金属羧酸链的二维网状层。2是具有羧酸桥连双核的一维准梯形链状结构。3是二维波浪层。其中2和3的三维超分子结构由丰富的氢键相互作用形成;而1的三维超分子结构通过范德华力堆积而成。研究了3个配合物的热重分析（TGA）,粉末X射线衍射（PXRD）和荧光性质。固态荧光光谱表明3个配合物的发射光谱与相应的辅助配体相似。此外,配合物3在紫外光照射下,在H₂O₂存在时对亚甲基蓝（MB）的降解表现出良好的光催化活性。     

Syntheses and crystal structures of two Zn(II) complexes, [Zn(Fura)2(2,2′-bipy)(H2O)] and [Zn(μ-dnbc)2] (Fura=Furoic acid, 2,2′-bpy=2,2′-bipyridine,dnba=3,5-dinitrobenzoic acid)

Two Zn(II) complexes, [Zn(Fura)₂(2,2′-bpy)(H₂O)] (1) and [Zn(µ-dnbc)₂] (2), have been synthesized and characterized by X-ray diffraction and IR spectra. 1 is a quaternary Zn(II) complex with ZnN₂O₃ configuration distorted square pyramid geometry; 2 is a Zn(II) coordination polymer with 1D double-helical chains bridged by 3,5-dinitrobenzoic acid.     

阴离子对构筑锌的肼配位卤族化合物的影响

采用含桥联双齿配体的过渡金属配合物来构筑多维无穷结构的研究是近年来晶体工程领域的一个热点。已经发现的结构有无穷链式、金刚石型、立方、梯式、蜂窝式、螺旋梯状与砖墙式等多种几何构型。其中一维无穷链式结构是最简单的一种构型，它不仅是理论模拟多维结构的最简模型，而且是构筑其他多维结构如分子梯式与二维层状结构的基元。     

Benzenedicarboxylate-modulated zinc(II)-3,5-bis(3-pyridyl)-1H-1,2,4-triazole frameworks: syntheses, structures and luminescent properties

Abstract  

Based on the polydentate ligand 3,5-bis(3-pyridyl)-1H-1,2,4-triazole (3,3′-Hbpt), three coordination compounds [Zn(3,3′-Hbpt)(ip)]·2H₂O (1), [Zn(3,3′-Hbpt)(5-NO₂-ip)]·H₂O (2), and [Zn(3,3′-Hbpt)₂(H₂pm)(H₂O)₂]·2H₂O (3) have been hydrothermally constructed with H₂ip, 5-NO₂-H₂ip and H₄pm as auxiliary ligands (H₂ip = isophthalic acid, 5-NO₂-H₂ip = 5-NO₂-isophthalic acid, H₄pm = pyromellitic acid). Structural analysis reveals that Zn(II) ions serve as four-coordinated, five-coordinated, and six-coordinated connectors in 1–3, respectively, while 3,3′-Hbpt adopts μ-N_py and N_py coordination modes in two typical conformations in these target coordination compounds. Dependently the applied ligand, compounds 1–3 exhibit either 1D channel, cage or chain structures, respectively. In addition, the luminescence properties of 1–3 have been investigated in the solid state at room temperature.     

Cadmium(II), manganese(II) and zinc(II) compounds

Three new compounds, [Cd(μ ₃ -Hpdh)(μ₂-Cl)] _n (1), Mn(Hpdh)₂(H₂O)₂ (2) and Zn(Hpdh)₂ (H₂O)₂ (3) (H₂pdh =?pyridine-2,3-dicarbo-2,3-hydrazide), have been synthesized and characterized by elemental analysis, IR spectra, TG and single-crystal X-ray diffraction. Under hydrothermal conditions, H₂pdh is generated by an in situ acylation of H₂pda (H₂pda =?pyridine-2,3-dicarboxylic acid) with hydrazine hydrate. Complex 1 features a 2D layer structure constructed by a dinuclear Cd(II) building block. In complexes 2 and 3, hydrogen bonding interactions connect mononuclear structures into 3D supramolecular frameworks.     

基于衣康酸配体构筑的两个锌配合物的合成、结构和荧光性质

通过水热法合成了两种锌配位聚合物{[Zn(ic)(bip)]·2H₂O}n (1)和[Zn(ic)(bpe)]n (2)(H₂ic=衣康酸,bip=3,5-二(1-咪唑基)吡啶,bpe=1,2-二(4-吡啶基)乙烯),并通过X射线单晶衍射和元素分析对其结构进行了表征.配合物1和2均为含有一维金属-羧酸链的二维(4,4)格子层结构.此外,对它们的热重、粉末X射线衍射和固体荧光性能进行了考察.与配体bip相比,1的发射光谱发生了明显的蓝移(~78 nm),可能归因于配体到金属的电荷转移;2显示与游离的bpe配体相似的荧光性质,轻微的红移可能是因为与金属离子之间的配位作用导致的.