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.     

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.     

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.     

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.     

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。     

Energy level engineering of charge selective contact and halide perovskite by modulating band offset:Mechanistic insights

Mixed cation and anion based perovskites solar cells exhibited enhanced stability under outdoor conditions,however,it yielded limited power conversion efficiency when TiO₂ and Spiro-OMeTAD were employed as electron and hole transport layer(ETL/HTL)respectively.The inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar(n-i-p)perovskite solar cells.By employing computational approach for uni-dimensional device simulator,the effect of band offset on charge recombination at both interfaces was investigated.We noted that it acquired cliff structure when the conduction band minimum of the ETL was lower than that of the perovskite,and thus maximized interfacial recombination.However,if the conduction band minimum of ETL is higher than perovskite,a spike structure is formed,which improve the performance of solar cell.An optimum value of conduction band offset allows to reach performance of 25.21%,with an open circuit voltage(VOC)of 1231 mV,a current density JSC of 24.57 mA/cm² and a fill factor of 83.28%.Additionally,we found that beyond the optimum offset value,large spike structure could decrease the performance.With an optimized energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56% can be attained.Our results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and how the improvement in PV performance can be achieved by adjusting the energy level offset.     

基于中国大学MOOC、慕课堂和QQ群三结合的分析化学课程在线教学实践

中国地质大学(武汉)分析化学课程团队采用国家精品在线开放课程作为课程资源、慕课堂作为智慧教学工具、QQ群作为在线讲授和辅导答疑的平台,成功地开展了分析化学课程在线教学实践。实践表明,基于MOOC、慕课堂和QQ群三结合的在线教学形式受到了学生的欢迎和喜爱,学生普遍易于接受,参与积极性高,初显教学效果较好。     

分析化学慕课课程平台的快速构建及教学实施方法探索

针对新型冠状病毒感染肺炎疫情对高校正常开学和课堂教学造成的影响,本校分析化学教研室积极响应教育部高等学校化学类专业教学指导委员会的倡议,快速筹备与构建了基于校内多层次信息化学习平台的在线慕课教学活动,以保障延期开学期间分析化学课程的教学安排,帮助与指导选课学生在疫情防控期间高效高质量地完成本课程的学习。本文从分析化学慕课课程的快速构建与特点,校内课程平台的学习及管理,微信群、QQ群及公共邮箱等辅助教学,以及学生的使用效果与学习诉求等几个方面进行探析,希望为提高分析化学的教学质量,探索新型教学方法提供数据支持,从而与学生一同完成课程的教学与学习,收获理想的成绩。     

MOOC资源的有效利用 ——基于SPOC的无机及分析化学教学改革

In view of the increasing quantity of MOOC curriculum construction and the utilization of MOOC resources, this paper puts forward how to efficiently make use of MOOC resources through deepening curriculum teaching reform. In this paper, the problems in MOOC teaching are summarized, and then the SPOC course is introduced. Along with introducing SPOC course, taking the course of inorganic and analytical chemistry in Huazhong Agricultural University as an example, four main functions of SPOC are expounded emphatically which include solving the problem of cultivating students' autonomous learning ability, solving the problem of obtaining knowledge from MOOC in a piecemeal way, solving the concern about the effect of online learning and solving the low participation of MOOC. It is concluded that the course of SPOC is an important way to make good use of MOOC. It is suggested that the co-construction and sharing of MOOC should be strengthened to enhance the efficiency of MOOC.     

促进物理化学在线教学质量的实践

During the special period in the epidemic COVID-19, the five-step online teaching mode focusing on learning outcome of students has been constructed based on the national high-quality MOOC in physical chemistry and various network technologies (i.e. MOOC class, Tencent QQ group and meeting platform), which is "guide to learn boost, self-study by MOOC, online testing, timely feedback, advanced discussion". It has been demonstrated that diversified online interactive teaching strategies can effectively promote the online teaching quality, through teachers giving full play to the leading roles, encouraging and guiding students to participate in the whole online teaching process.     

基于物理化学MOOC的混合式教学实践

Based on the massive open online course (MOOC) of physical chemistry from Chinese university MOOCs platform, the authors introduce some initiatives and experiences in the MOOC course construction and the application for undergraduate teaching in Dalian University of Technology. The blended teaching and learning mode made up of "online" and "offline" was put into practice in other universities, and a new "1 + M + N" mode to provincial cross-school sharing has been demonstrated. It was shown that only the enhancement of MOOC teaching be highly valued throughout whole course of teaching, the students' quality and ability could be better cultivated followed by improving teaching quality.     

基于MOOC的“无机化学Ⅱ”课程在线教学的探索与实践

During the battle against COVID-19 epidemic, the inorganic chemistry teaching team of Jilin University carried out online teaching of student-centered "inorganic chemistry Ⅱ" course based on "inorganic element chemistry" MOOC with Chaoxing learning platform and QQ group as the auxiliaries. Through the big data support and interactive communication section of Chaoxing learning platform, the learning situation of students in the three learning links of "pre-class, in-class, after-class" was timely tracked and analyzed. Practice showed that online teaching could accomplish teaching and learning effectively.     

Green analytical chemistry: Opportunities for pharmaceutical quality control

This review article summarizes the opportunities for utilizing the green analytical chemistry (GAC) techniques and principles in the field of quality control (QC) of pharmaceuticals. Green analytical chemistry is considered a branch of the green chemistry based on the principles overlapping with the goals of sustainable development. General definitions of quality and quality control, the principles of GAC, proposals for greener sample pretreatment and greener chromatographic method of analysis applied in QC laboratories are discussed herein. The main goal is to achieve more eco-friendly analysis in QC laboratories through different strategies and techniques, replace toxic reagents, and modify or replace analytical methods and/or techniques with safer ones, making it possible to dramatically reduce the amounts of reagents consumed and waste generated.     

The current state of analytical control in Lithuania

In Lithuania research and development in chemical analysis are concentrated in scientific institutes and universities. The main fields of interest focus on biosensors, electrochemical sensors, sampling techniques and methods, study of atomization processes in spectrochemical analysis and noise evaluation in analytical measurements. Some laboratories also take part in international environmental monitoring programmes. There are about 50 researchers at the Ph.D. level engaged in analytical chemistry and several hundred technicians specialized in the field of analytical control. About one hundred chemical laboratories are active in scientific institutes, universities and factories. Specialized laboratories of chemical analysis are at the disposal of Environmental Control and Health Protection Departments and forensic investigation organizations. So far no laboratories are accredited according to the ISO 9000 norms. Special courses on analytical chemistry are offered at a few schools of higher education in the country. Only at the Department of Analytical Chemistry of the University of Vilnius specialized programmes are available to postgraduate students working towards a Ph.D. to improve their skills in current techniques of analytical chemistry. Recently the Technical Committee TC-16 for Chemical Analysis was formed within the standardization system of Lithuania. Its main activities are centered on issues such as national terminology, certified reference materials (CRMs), analytical methods and analytical quality assurance. There are numerous problems related to national terminology, the preparation of special documents in the field of analytical control and the production of regional environmental CRMs. Problems, also arise in obtaining and using CRMs for analytical instrument calibration and validation.     

充分利用优质网络资源和教学立方平台，助力配位化学线上教学

In early 2020, because of the outbreak of COVID-19, students are unable to return school on time and normal teaching activities are postponed. In order to implement the requirement of "No suspension of classes" proposed by the Ministry of Education, and to ensure the teaching quality at the same time, the coordination chemistry teaching team from Nanjing University successfully carried out the exploration and practice of online teaching of coordination chemistry by using the MOOC of coordination chemistry on "Wisdom Tree" platform as the curriculum resource, QQ Live or Tencent Meeting as the online teaching tool and Pedagogy Square as the intelligent teaching platform. This teaching form reorganizes and optimizes the available resources online, and implements the student learning process evaluation and the teacher teaching evaluation. The feedback from students and teachers indicates the success of this teaching form.     

分析化学在线开放课程群建设的创新与实践

重点探索分析化学在线开放课程群的建设,依托数字资源和网络平台为分析化学教学空间构建提供平台支撑,推动课堂教学模式的结构性变革。