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.     

缩醛/缩酮的合成研究进展

民以食为天。然而,鲜有中文文献专业、系统地介绍与食物相关的化学反应,这无疑导致化学课程的教学脱离现实生活,阻碍了大众透过现象看到食物背后的本质。因此,本文重点介绍了为食物带来独特美味及色泽的非酶褐变反应,主要包括焦糖反应、美拉德反应、维生素C的氧化反应等;并从化学的角度探讨食物中与医学相关的分子转变现象,如食盐中碘在体内的转化,反式脂肪酸对健康的影响,酒精的代谢过程等。使化学课程的教学密切联系现实生活,为化学与食品科学、医学等学科之间架起桥梁。     

我国理论化学2008年研究进展简述

2008年中国大陆理论化学工作者在多个领域的研究都取得了新进展. 这些领域包括密度泛函理论的方法和应用、化学动力学和反应势能面的构造、光化学反应动力学、生物分子及生命现象、立体化学等. 本文简述了2008年中国大陆理论化学方面的研究工作进展, 重点突出了几个引起国际同行广泛关注的亮点.     

化学教师模型认识与模型教学观的关系研究*

主要使用李克特式量表问卷测查了256名中学化学教师的模型认识与模型教学观的结构与水平,并使用结构方程模型进一步探查化学模型认识与模型教学观的关系。结果表明:(1)化学教师对化学模型的描述与解释功能以及模型的暂定性具有较好的认识,但对模型预测功能认识不足;(2)化学教师在模型教学中倾向于使用模型描述、解释或预测化学现象,并且较认可以学生为中心的模型教学,但缺乏对模型暂定性的反思;(3)化学教师的模型认识基本上可预测其模型教学观,如关于模型功能的认识能显著预测其模型教学观。文末据此为我国化学教师培训及其研究提出相关建议。     

分子间选择性作用力和控制论化学-金松寿教授研究简介

金松寿教授是著名的量子化学及化学动力学专家。年近九旬的他如今仍然锲而不舍地在学习、研究,把握化学研究的发展方向。他在催化集团结构适应性及无机化合物溶解度领域做了大量的工作,重要的成就是发现了选择性分子间力并用以阐释物性如溶解度、吸附、色谱中的反常现象,还可以解释溶媒对反应速度的影响。相似的选择力后来被外国科学家在超分子研究中得到证实和发展。他还推动了控制论化学的应用,对化学中的许多疑难繁琐的现象给出清晰满意的解释。     

Mixis and Diagnôsis: Aristotle and the “Chemistry” of the Sublunary World

In On Generation and Corruption 1.10, Aristotle introduces the new idea of “chemical mixture” (mixis) to explain the constitution of those homogeneous substances from which all things in the sublunary world are comprised. In a mixture, the ingredients interact with one another to give rise to a new substance, qualitatively different, yet preserving the original ingredients in potentia, so that they can be separated again. In Book IV of the Meteorologica, Aristotle further suggests that bodies may be “diagnosed” according to certain passive properties, such as the fusibility of metals. While his theory of mixture has often led historians of science to identify Aristotle as one of the precursors of chemical science, his ideas have also been criticised as archaic, and implicated in a qualitative conception of the cosmos that delayed progress towards quantifying natural phenomena. In this paper, I take up the defence of Aristotle's theory by showing that his concept of mixture is not an obstacle to the development of natural science and chemistry, but, on the contrary, opens the way by offering an advanced model of qualitative analysis which does not exclude the possibility of quantitative development.     

Determination of Oxolinic Acid in Toasted Eel Tissue by Microwave Extraction and HPLC with Fluorescence Detection

Oxolinic acid (OXA) is a synthetic quinolone antimicrobial agent extensively used to treat infections in fish farming. Determination of oxolinic acid residue in food products made from such fish is required for safety and trade export.     

Combinatorial chemistry in food research

This mini-review is concerned with emerging applications of combinatorial chemistry relevant to the needs of the food industry. More specifically, recent advances in the use of combinatorial methods for the identification and analysis of flavours, "food chemical" libraries as a potential source of enzyme inhibitors for the food industry and the utility of biocatalysis for the generation of molecular diversity are discussed.     

非平衡非线性化学

概述了非平衡非线性化学的主要研究内容和最新进展,着重介绍了各种非平衡非线性化学现象以及与之有关的非平衡态热力学理论和非线性化学动力理论;介绍一些典型的理论方法和实验手段以及涨落化学的概念;讨论了非平衡非线性化学研究的意义以及与其它科学尤其是生物学的联系。     

Connecting the philosophy of chemistry,green chemistry,and moral philosophy

This paper aims to connect philosophy of chemistry, green chemistry, and moral philosophy. We first characterize chemistry by underlining how chemists: (1) co-define chemical bodies, operations, and transformations; (2) always refer to active and context-sensitive bodies to explain the reactions under study; and (3) develop strategies that require and intertwine with a molecular whole, its parts, and the surroundings at the same time within an explanation. We will then point out how green chemists are transforming their current activities in order to act upon the world without jeopardizing life. This part will allow us to highlight that green chemistry follows the three aforementioned characteristics while including the world as a partner, as well as biodegradability and sustainability concerns, into chemical practices. In the third part of this paper, we will show how moral philosophy can help green chemists: (1) identify the consequentialist assumptions that ground their reasoning; and (2) widen the scope of their ethical considerations by integrating the notion of care and that of vulnerability into their arguments. In the fourth part of the paper, we will emphasize how, in return, this investigation could help philosophers querying consequentialism as soon as the consequences of chemical activities over the world are taken into account. Furthermore, we will point out how the philosophy of chemistry provides philosophers with new arguments concerning the key debate about the ‘intrinsic value’ of life, ecosystems and the Earth, in environmental ethics. To conclude, we will highlight how mesology, that is to say the study of ‘milieux’, and the concept of ‘ecumeme’ proposed by the philosopher and geographer Augustin Berque, could become important both for green chemists and moral philosophers in order to investigate our relationships with the Earth.