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.     

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。     

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.     

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.     

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.     

基于稀土配合物的有机光盲型紫外探测器

使用二苯甲酰甲烷-二苯菲罗啉-铕(Eu(DBM)3BPhen)作为电子给体和[6,6]-苯基-C61-丁酸酸甲酯([60]PCBM)作为电子受体制备了一种新型的有机光盲型紫外探测器.在光强为2.1 mW cm-2且波长为360 nm的紫外光照射下,获得了26 mA W-1的响应度和9.1%的外量子效率,这是由于Eu(DBM)3BPhen的强紫外光吸收能力和长达300μs的激子寿命使得给受体界面处具有较高的激子解离率.在把[60]PCBM掺入Eu(DBM)3BPhen后,观察到了明显的光致发光猝灭和光电导现象.由于材料较低的载流子迁移率和受陷激子的缓慢释放,在紫外光照射关闭后,观察到了较强的持续光电导现象.     

Photo-and Electro-luminescence of the New Ternary Europium(III) Complex

In recent years, the interest in developing luminescent lanthanide complexes has been greatly stimulated by their potential use in electroluminescent displays1. Europium complexes appear most attractive in view of the high photoluminescent efficiency and the high monochromatic red light that are widely exploited in full-color displays2. It has been approved that the second ligand plays an important role in europium complexes, the synergistic complexation of the second ligand can not only lead …     

Rectification of excitation with bathochromic shift induced by intense absorption of organic ligands during emission measurement of Eu(III) complex

Bathochromic shift in excitation spectrum was observed during emission measurement of Eu(DBM)(3)Phen containing dilute solution in methyl methacrylate (MMA). Detailed analysis shows that the reason of bathochromic shift is not the formation of molecule aggregation. It is caused by the intense absorption of ligands in the complex. Based on this model, a new method has been established to rectify excitation spectra before emission measurement of systems with different concentration. There exists a critical value of the absorption strength, which is 0.87 from calculation. Higher absorption than this value will cause the bathochromic shift of excitation peak. The wavelength whose absorbance is 0.87 will be the position of the strongest excitation peak. With 200 ppm and 500 ppm Eu(DBM)(3)Phen as the standard sample, relations between relative concentration and wavelength of excitation peak in Eu(DBM)(3)Phen system were deduced and plotted. Theoretical curves are in good agreement with experiment data except extra-dilute concentration, for partial decomplexation of the beta-diketonate and phenanthroline ligands.     

Reversible modulation in luminescence intensity of a single vesicle composed of diblock azo-copolymer and tris(dibenzoylmethanate)(phenanthroline)europium(III)

Tris(dibenzoylmethanate)(phenanthroline)europium(III)[Eu(DBM)(3)Phen]-doped amphiphilic vesicles were obtained by self-assembling of poly(N-isopropylacrylamide)-b-poly[6-[4-(4-methylphenyl-azo) phenoxy] hexylacrylate] (PNIPAM(83)-b-PAzoM(20)) in presence of Eu(DBM)(3)Phen in the mixed solvent of THF/H(2)O (50/50 vol.%). Their optical properties were studied by UV-vis and fluorescence spectroscopies. The UV-vis spectrum showed that the electronic transition bands of azobenzene and Eu(DBM)(3)Phen were overlapped at about 365 nm and the main peak of fluorescence emission band appeared at 612 nm. So the vesicles showed obvious red luminescence. It was found that the fluorescence intensity of a single Eu(DBM)(3)Phen-doped vesicle could be modulated by irradiation with UV and visible light due to the reversible trans-cis-trans photoisomerization reaction of azobenzene moiety. Possible energy allocation process for this property was discussed in details.     

Luminescence of Eu(DBM)3Phen-doped in azobenzene-containing copolymers—Effects of absorption overlapping of two components

Poly(N-isopropylacrylamide)-b-poly{6-[4-(4-methylphenyl-azo)phenoxy]hexylmethacrylate} (PNIPAM₃₂-b-PAzoMM₈) and poly(N-isopropylacrylamide)-b-poly{6-[methyl(4-nitrophenyldiazenyl)phenyl]aminohexylmethacrylate} (PNIPAM₃₂-b-PAzoNO₁₀) were prepared by reversible addition–fragmentation chain transfer (RAFT) radical polymerization. The optical properties of Eu(DBM)₃Phen (Eu, Europium; DBM, dibenzoylmethide; Phen, 1,10-phenanthroline)-doped azobenzene-containing copolymer vesicle solutions were studied by UV–vis and fluorescence spectroscopy. When the electronic transition bands of azobenzene and Eu(DBM)₃Phen overlapped at about 350 nm in PNIPAM₃₂-b-PAzoMM₈, the fluorescent emission intensity at 612 nm of Eu(DBM)₃Phen could be modulated by irradiation with UV and visible light. However, when the absorption of the azobenzene-moiety red-shifted to 477 nm in PNIPAM₃₂-b-PAzoNO₁₀, the luminescence intensity of Eu(DBM)₃Phen was not affected any longer. The difference between these two systems was possibly caused by the energy allocation in the luminescence process, which was discussed in detail.     

含有电子传输基团的双齿配体及铕配合物Eu(DBM)3(DPOP)的制备与发光性能的研究

1, 3, 4-oxadiazole-contanining ligand DPOP(DPOP=2-(11-dipyrido[3, 2-a: 2′, 3′-c]phenazine)-5-p-tolyl-1, 3, 4-oxadiazole) was synthesized by a convenient method and characterized by elemental analysis, IR, ¹H NMR. Then, corresponding Eu(Ⅲ) complex [Eu(DBM)₃(DPOP)] (DBM=1, 3-diphenyl-1, 3-propanedionate) was prepared and characterized by elemental analysis, IR. The photophysical properties of ligand and its europium complex were investigated. The ligand emitted at 443 nm. There were different PL spectra in solid state and in solution of Eu(DBM)₃(DPOP). There are two fluorescent peaks at 614 nm, 400 nm in dichloromethane solution of Eu(DBM)₃(DPOP), but in solid state only red emission was observed. This result indicated that efficient energy tranfer could take place from DPOP ligand to europium ion in Eu-complex solid.     

聚丙烯酸-铕-二苯甲酰甲烷配合物及其荧光性质的研究

将铕的有机配合物NaEu(DBM) 4与聚丙烯酸反应获得铕配位聚合物 (PAA Eu3+ DBM) .此配位聚合物是白色固体 ,不溶于大部分有机溶剂 ,只能溶于丙三醇和异丙醇的混合溶剂 .采用红外光谱、紫外光谱、X射线光电子能谱、电导率、元素分析和荧光光谱等手段对其结构和荧光性质进行表征 ,确定其配位组成和结构即每个铕离子分别与一个DBM分子和PAA分子中二个链节羧基发生配位 .荧光光谱表明PAA Eu3+ DBM有很好的荧光性     

三元铕配合物Eu(DBM)3L1的合成、晶体结构及发光性能

新型三元铕配合物Eu(DBM)3L1(DBM=二苯甲酰甲烷,L1=2-(3-硝基苯基)-咪唑并[4,5-f]-1,10-邻二氮杂菲)的晶体属单斜晶系,Cc空间群.中心铕离子分别与DBM配体的六个氧原子和第二配体的两个鳌合氮原子配位,形成八配位的扭曲四方反棱柱构型.配合物中性配体的共轭平面与相邻分子的DBM苯环平面(C(25),C(26),C(27),C(28),C(29))之间有明显的π-π相互作用.在紫外光激发下,配合物表现出较强的Eu3+的特征发射,第二配体对中心离子有较强的敏化发光作用.     

三核铕配合物Eu3(DBM)9(TDMB)的星型配体制备与发光性能

用一种星型配体1,3,5-三((4,5-二氮芴-9-肟)甲基))-苯合成了三核铕配合物Eu₃(DBM)₉(TDMB)(DBM=1,3-二苯基-1,3-丙二酮),合成的配合物用元素分析,红外,氢核磁共振进行了表征。研究了配体与配合物的光物理性质。配合物在固态和溶液中具有不同的发光光谱,在二氯甲烷中分别在612 nm和414 nm有荧光峰,固态时只有红光发射,这一结果显示在固态时从TDMB配体到铕离子的能量传递更有效。     

Visible light sensitized attapulgite-based lanthanide composites: microstructure, photophysical behaviour and biological application

Attapulgite, an extremely stable fibrillar mineral present in nature, is a promising new carrier of luminescent lanthanide complexes for further applications. A europium complex Eu(DBM)(3)(H(2)O)(2) (HDBM = dibenzoylmethane) was covalently coupled onto modified attapulgites (or silica nanoparticles) via a ligand exchange reaction, generating attapulgite-based ternary europium complexes. The composites were characterized by CHN elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for Eu(3+) content, powder X-ray diffraction (XRD), thermogravimetry (TG) and UV-vis absorption spectra. The results indicate that the Eu(3+) complex was grafted covalently to the outer surfaces of attapulgites (or silica nanoparticles) and modifications by coupling agents containing different alkoxide groups (aminopropyltriethoxysilane (APTES) or aminopropylmethyldiethoxysilane (APMDES)) led to different grafting ratios. The structures of these composites were further evidenced by the determination of photophysical behaviours and coordinated water molecules of the complexes linked to matrices. Attapulgite-based lanthanide composites linked by APTES can be excited by visible light, with a wide excitation wavelength range from UV to visible light (a maximum at 398 nm), long luminescence lifetime (503 μs), high quantum yield (48%) and improved exposure durability. When incubated with HeLa cells at 37 °C, the fluorescence of matrix-APTES-cpa-Eu(DBM)(3) is observed on the cell membrane. Moreover, the low cytotoxicity of our present system results in potential applications for cell imaging in biological systems.