欠电位沉积研究现状——II.欠电位沉积的研究方法及其应用

总结了主要的欠电位沉积(upd)的原位研究方法, 包括电化学研究方法(循环伏安(CV)、计时电流(CHR)和电化学阻抗谱(EIS))、界面分析方法(电化学石英晶体微天平(EQCM)和电化学扫描隧道显微镜/电化学原子力显微镜(ECSTM/ECAFM))及X射线分析技术(X 射线吸收谱(XAS)和表面X射线散射(SXS)). 根据这些研究方法, 总结和探讨了许多体系的upd特征, 分析了upd微观特征与宏观的测试结果的对应关系及其原理. 此外, 探讨了基于这些研究方法得出的关于upd的重要结论, 并对比分析了上述研究方法的优缺点. 在upd应用领域的研究方面, 主要从四个方面进行了概述, 涉及功能材料电合成、电分析应用、电化学原子层外延(ECALE)和表征贵金属(或纳米)材料电化学活性面积(ECSA), 并简析了上述应用研究中涉及的关于upd 过程的原理. 最后, 总结了upd研究方法和应用研究的现状并展望了其未来发展趋势.     

检测活性硫物种小分子荧光探针的研究进展

总结了近两年来检测生物硫醇、H_2S以及SO_2衍生物荧光探针的研究现状,着重讨论了探针设计的传感机制、传感性能和生物应用方面的特征。检测生物硫醇方面,主要介绍了涉及多反应位点的多通道探针用于区分谷胱甘肽(GSH)、半胱氨酸(Cys)和同型半胱氨酸(Hcy);检测H_2S方面,重点介绍了基于叠氮基还原和亲核反应这两种机制设计的探针;检测SO_2衍生物方面,主要总结了根据迈克尔加成法和醛的加成机制设计的探针。这为构建新型荧光探针以研究活性硫物种的生理和病理作用奠定了基础。     

二维金属有机框架纳米片的合成及在超电容和电催化领域的应用

二维金属有机框架(2D MOF)纳米片具有丰富且易暴露的表面活性位点、 高度有序的孔结构以及多样且可调的化学成分, 在电化学能量存储与转化中有利于降低反应电位, 提高扩散速率和反应速率. 关于2D MOF应用于电化学存储与转化的研究已有大量报道. 本文综合评述了近几年2D MOF的合成进展及其在超电容(SC)、 析氧反应(OER)、 析氢反应(HER)、 氧还原反应(ORR)和二氧化碳还原反应(CRR)的应用, 并对2D MOF作为电催化材料的研究现状和发展前景进行了总结与展望.     

甲烷直接催化氧化制备甲醇近期研究进展北大核心CSCD

甲烷合成甲醇的方法包括间接法和直接催化氧化(DMTM)法,但是间接法对设备要求高,且甲烷转化率与甲醇选择性均不理想,DMTM法可通过一步反应高选择性制备甲醇,有巨大的应用潜力。对于甲烷DMTM法合成甲醇,均相催化体系通常需要特殊反应介质与贵金属催化剂相结合,虽然反应效率高,但对反应设备有腐蚀性,产物不易分离,应用前景差。液相-异相催化一般使用H_(2)O_(2)作为氧化剂,Au、Pd、Fe和Cu等金属元素作为催化剂主要活性组分,·OH是主要的氧化活性物,可在低温下实现甲烷的活化氧化。因此,异相催化体系是目前研究的主流。气相-异相催化主要使用O_(2)和N_(2)O为氧化剂,前者氧化性更强,后者对于产品选择性更好,此外,厌氧体系中H_(2)O也可直接作为氧供体,常用Cu、Fe、Rh等元素作为催化剂。沸石分子筛是使用最广泛的载体,金属氧化物、金属有机骨架化合物(MOFs)和石墨烯也均有涉及,多金属协同催化已经取得了很好的效果。本文主要总结与概述了热催化甲烷直接催化氧化制备甲醇的近年相关研究,并对今后的研究方向做出了展望。     

基于喹啉的金属离子荧光探针的研究进展

主要总结了近几年来基于喹啉及其衍生物的金属离子荧光探针的研究进展,重点讨论了检测Cd~(2+)、Zn~(2+)的喹啉类荧光探针,主要从探针的荧光响应能力、配位机制和实际应用几方面的特征进行了分析总结。为进一步设计与构建新型金属离子荧光探针提供了思路。     

SOLO分类理论在初高中化学教育中的应用研究对比*

对2015-2020年SOLO分类理论在中学化学教育中应用研究的62篇文献进行分析,总结出SOLO分类理论应用研究的5个方面:(1)指导习题编制与评分标准确立;(2)分析中、高考试题;(3)指导教学实践;(4)指导学习心理实证研究;(5)指导教学评价。并通过对其在初高中化学教育中应用研究的情况对比,总结出高中教师的成功经验可为初中教师的相关研究提供参考,并对中学教师运用SOLO分类理论解决教学中的问题提出建议。     

欠电位沉积研究现状——I.欠电位沉积理论

欠电位沉积(upd)具有重要的理论和应用价值, 一直是电化学领域的研究热点. upd 过程理论研究的实质主要为围绕沉积基体、沉积物种和阴离子(或其他有机添加剂)三者在upd过程中的相互作用关系和规律的研究. 本文从upd 过程热力学和动力学两个方面出发, 系统地概述了近年来国内外在upd 理论研究方面的进展.在upd过程热力学方面, 从欠电位位移(ΔE_upd)、upd电吸附价(γ)、温度对upd的影响和电化学吸附等温线四个方面进行了阐述, 概括和分析了upd 过程热力学研究中涉及的相关数学表达式及其应用; 在其动力学方面, 主要概述了upd成核和生长过程动力学, 总结介绍了借助相关数学模型在分析upd过程动力学特征方面的研究. 此外, 简单介绍了计算化学在upd 研究中的应用成果; 最后, 总结了upd 的理论研究现状并展望了upd 的未来研究方向.     

量子化学的Gaussian-2理论及其应用与化合物的标准生成烩预测

本文较为全面地综述了Gaussian-1, Gaussian-2(简称G1,G2)理论以及简化的G2 CMP2 ) ,G2 (MP3)理论,将其主要结果进行了比较分析。关于G2理论的应用,除了较为详细地综述了几年来理论在重现实验数据、评价实验数据、预测实验数据及研究化学反应途径等方面的应用外,还结合我仁近期研究结果的主要结论讨论了该理论在研究等电子一等自旋,价层等电一等旋,等旋及非等旋化学反应的能量计算中的应用情况,以及该理论在预测化合物的标准生成蛤方面的应用情况。     

铜基催化剂用于一氧化碳催化消除研究进展

催化消除CO主要包括CO的完全氧化(CO-COOX)和优先氧化(CO-PROX).首先,结合本课题组的相关研究,按照催化剂体系介绍了Cu基催化剂在CO-COOX中的活性物种和组分之间的相互作用.其次,对用于富氢气氛下CO-PROX的Cu基催化剂进行了系统的分类总结,重点阐述了CuO-CeO2催化剂的制备方法、助剂改性、载体调变以及过渡金属离子掺杂(CuO/Ce1-xMxO2)、反相结构(CeO2/CuO)等方面对CO-PROX催化性能的影响.最后,总结了Cu基催化剂在CO-PROX中存在的问题,并展望了未来的研究趋势.     

变换催化剂研究进展

烃类化合物的水蒸汽重整与水煤气变换反应(简称变换反应)组合是廉价制取氢气的主要方式.经过80多年的研究和实践,工业化的变换催化剂已基本定型.近年来由于燃料电池技术的飞速发展,有关变换催化剂的研究与开发又重新引起人们的兴趣与关注.本文在总结传统变换催化剂研究进展情况的基础上,重点介绍了以燃料电池应用为目的变换催化剂的研究进展.总结表明,"(贵)金属/载体" 型双功能催化剂已经成为变换催化剂的主要研究方向.(贵)金属和载体种类、制备方法和条件等对催化剂粒径分布、体相织构、表面性质和活性等都有很大影响.虽然与传统变换催化剂相比,"(贵)金属/载体" 型双功能变换催化剂体现了更优良的性能,但与燃料电池商业化应用的要求还有一定的差距.     

Double pulse laser induced breakdown spectroscopy applied to natural and artificial materials from cultural heritages : A comparison with micro-X-ray fluorescence analysis

The laser-induced breakdown spectroscopy (LIBS) is an applied physical technique that has shown in recent years its great potential for rapid qualitative analysis of materials. Thanks to the possibility to implement a portable instrument that perform LIBS analysis, this technique is revealed to be particularly useful for in situ analysis in the field of cultural heritages. The purpose of this work is to evaluate the potentiality of LIBS technique in the field of cultural heritages, with respect to the chemical characterization of complex matrix as calcareous and refractory materials for further quantitative analyses on cultural heritages. X-Ray Fluorescence (XRF) analyses were used as reference. Calibration curves of certified materials used as standards were obtained by XRF analyses. The LIBS measurements were performed with a new mobile instrument called Modì (Mobile Double pulse Instrument for LIBS Analysis). The XRF analyses were performed with a portable instrument ArtTAX. LIBS and XRF measurement were performed on both reference materials and samples (bricks and mortars) sampled in the ancient Greek–Roman Theatre of Taormina. Although LIBS measurements performed on reference materials have shown non linear response to concentrations, and so we were not able to obtain quantitative results, an integrated study of XRF and LIBS signals permitted us to distinguish among chemical features and degradation state of measured building materials.     

Double pulse laser induced breakdown spectroscopy applied to natural and artificial materials from cultural heritages: A comparison with micro-X-ray fluorescence analysis

The laser-induced breakdown spectroscopy (LIBS) is an applied physical technique that has shown in recent years its great potential for rapid qualitative analysis of materials. Thanks to the possibility to implement a portable instrument that perform LIBS analysis, this technique is revealed to be particularly useful for in situ analysis in the field of cultural heritages. The purpose of this work is to evaluate the potentiality of LIBS technique in the field of cultural heritages, with respect to the chemical characterization of complex matrix as calcareous and refractory materials for further quantitative analyses on cultural heritages. X-Ray Fluorescence (XRF) analyses were used as reference. Calibration curves of certified materials used as standards were obtained by XRF analyses. The LIBS measurements were performed with a new mobile instrument called Modì (Mobile Double pulse Instrument for LIBS Analysis). The XRF analyses were performed with a portable instrument ArtTAX. LIBS and XRF measurement were performed on both reference materials and samples (bricks and mortars) sampled in the ancient Greek–Roman Theatre of Taormina. Although LIBS measurements performed on reference materials have shown non linear response to concentrations, and so we were not able to obtain quantitative results, an integrated study of XRF and LIBS signals permitted us to distinguish among chemical features and degradation state of measured building materials.     

Photocatalytic Reduction of CO2 on TiO2 and Other Semiconductors

Rising atmospheric levels of carbon dioxide and the depletion of fossil fuel reserves raise serious concerns about the ensuing effects on the global climate and future energy supply. Utilizing the abundant solar energy to convert CO₂ into fuels such as methane or methanol could address both problems simultaneously as well as provide a convenient means of energy storage. In this Review, current approaches for the heterogeneous photocatalytic reduction of CO₂ on TiO₂ and other metal oxide, oxynitride, sulfide, and phosphide semiconductors are presented. Research in this field is focused primarily on the development of novel nanostructured photocatalytic materials and on the investigation of the mechanism of the process, from light absorption through charge separation and transport to CO₂ reduction pathways. The measures used to quantify the efficiency of the process are also discussed in detail.     

Mechanosorption of carbon dioxide by Ca- and Mg-containing silicates and alumosilicates. Sorption of CO<Subscript>2</Subscript> and structure-related chemical changes

The discovery of the unusual ability of Ca- and Mg-containing silicates in certain grinding regimes to absorb carbon dioxide from the environment in amounts comparable to the mass of the ground sample has stimulated interest in the study of mechanochemical effects. The range of objects for studying natural minerals, such as labradorite (CaAl₂Si₂O₈)_0.562(NaAlSi₃O₈)_0.438, oligoclase (CaAl₂Si₂O₈)_0.148(NaAlSi₃O₈)_0.852, diopside CaMgSi₂O₆, and akermanite Ca₂MgSi₂O₇, as well as synthetic minerals gehlenite Ca₂Al₂SiO₇ and wollastonite CaSiO₃, is expanded to develop the model of deep mechanosorption of CO₂ and to derive equations that allow the kinetic analysis of the absorption of carbon dioxide by silicates in the course of mechanochemical activation to be performed. Regularities revealed previously and analogies to the processes that occur upon the dissolution of carbon dioxide in silicate melts, are generalized. Data on the absorption of carbon dioxide by Ca- and Mgcontaining silicates and alumosilicates, depending on the duration of mechanochemical activation in an AGO-2 centrifugal planetary mill in the atmosphere of CO₂ at a pressure of 10⁵ Pa, are obtained. Based on the data of X-ray phase analysis and IR spectroscopy, structural chemical changes in minerals and the forms of carbon dioxide in mechanochemically activated samples are discussed. It is shown that the intense penetration of gas molecules in particle bulk and their “dissolution” in structurally disordered silicate matrix in the form of distorted CO ₃ ^2? ions occurs upon mechanosorption.     

Indirect Spectrophotometric Method for Determination of Sulfur Dioxide

Abstract

An operationally inexpensive and satisfactory analytical procedure for sulfur dioxide is proposed. The reagent 3-methyl-1,2-cyclopentanodione dithiosemicarbazone has been used to determine trace amounts of sulfur dioxide indirectly using the reduction of Fe(III) to Fe(II) principle. In order to find the optimal conditions for SO₂ determination, properties of 3-Me-CPDT-Fe(II) complex such as its composition, stability and free energy change of formation have been determined. The best conditions for the complex formation such as standing time, pH, wavelength and the effect of interfering ions are described. The complex has been used with success in spectrophotometric determination of SO₂. The procedure can determine down to 0.63 μg and recoveries are better than 97.5%. The method is also suitable for determination of sulfur dioxide in the air provided that interfering gases such as H₂S and NO₂ are removed.     

Carbon Dioxide as a Raw Material: The Synthesis of Formic Acid and Its Derivatives from CO2

The use of carbon dioxide as a raw material for chemical syntheses is an ecologically and economically valuable extension to the carbon sources used at the present time. In order to convert the thermodynamically stable and comparatively unreactive CO₂ molecule into the desired product in an efficient manner, suitable reaction conditions and activation mechanisms must be found. The catalytic reduction of CO₂ to formic acid and its derivatives has been intensively studied in recent years. A number of new approaches to the synthesis of formic acid from CO₂ have reached such a state of knowledge that continuing development may well lead to industrial-scale operation in the near future. This can to a large extent be attributed to the fruitful interaction between investigative work into reaction mechanisms and the development of new catalytic systems.     

FTIR and GC as complementary tools for analysis of corrosive gases

The gas metrology laboratory of the National Metrology Institute of South Africa has developed methodology for the gravimetric preparation of corrosive gas mixtures such as nitric oxide (NO) in nitrogen, as well as sulphur dioxide (SO₂) in nitrogen or synthetic air. Fourier transform infrared (FTIR) spectroscopy has been used to analyse for trace and ultra trace levels of infrared active gaseous species, such as NO, nitrogen dioxide and SO₂ that are difficult to analyse by other means. These corrosive gas mixtures are also analysed using gas chromatography with pulsed helium ionisation detection to complement the work done using FTIR with infrared active impurities. A comparison between the techniques of FTIR, gas chromatography and non-dispersive infrared spectroscopy for corrosive gas analysis is also presented.     

Applications of Titanium Dioxide Nanostructure in Stomatology

Breakthroughs in the field of nanotechnology, especially in nanochemistry and nanofabrication technologies, have been attracting much attention, and various nanomaterials have recently been developed for biomedical applications. Among these nanomaterials, nanoscale titanium dioxide (nano-TiO₂) has been widely valued in stomatology due to the fact of its excellent biocompatibility, antibacterial activity, and photocatalytic activity as well as its potential use for applications such as dental implant surface modification, tissue engineering and regenerative medicine, drug delivery carrier, dental material additives, and oral tumor diagnosis and treatment. However, the biosafety of nano-TiO₂ is controversial and has become a key constraint in the development of nano-TiO₂ applications in stomatology. Therefore, in this review, we summarize recent research regarding the applications of nano-TiO₂ in stomatology, with an emphasis on its performance characteristics in different fields, and evaluations of the biological security of nano-TiO₂ applications. In addition, we discuss the challenges, prospects, and future research directions regarding applications of nano-TiO₂ in stomatology that are significant and worthy of further exploration.     

Silicon dioxide surface reconstruction stimulated by adsorption interaction

The MM2 molecular mechanics method is used for calculations on the adsorption complex formed on the surface of silicon dioxide due to adsorption of gases such as H₂O, O₂, NH₃, HF. The results of modeling are in good agreement with experimental data; these results explain why film thickness decreases after adsorption and support our hypothesis about reconstruction of the surface layer stimulated by the adsorbed molecule.     

Metal-Organic Frameworks for Efficient Electrochemical Reduction of Carbon Dioxide

The large concentration of carbon dioxide (CO₂) in the atmosphere can be utilized in industrial production using effective electrocatalysts such as metal-organic frameworks (MOFs). Due to good properties such as high surface area, designable functionality, and uniform constitution, MOFs are regarded as promising electrocatalysts for the carbon dioxide electrochemical reduction reaction (eCO₂RR). This review covers the importance, challenges, and mechanism of eCO₂RR, and simply discusses the progress in the synthesis methods and characterization of MOFs. The review also thoroughly discusses the advances of single metal-based MOFs, mixed metal-based MOFs, and MOF derivatives as electrocatalysts for efficient eCO₂RR.