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.     

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.     

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。     

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.     

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.     

NiFe2O4对刚果红的光催化降解性能研究

采用水热法合成了尖晶石型NiFe₂O₄,并利用X射线粉末衍射仪对其物相进行了表征,利用紫外-可见分光光度计对其光催化降解刚果红的性能进行了研究。以刚果红为光催化降解底物,探究了刚果红初始浓度、催化剂用量、溶液pH、不同光源等因素对NiFe₂O₄光催化降解刚果红活性的影响。结果表明,当刚果红溶液浓度为20 mg/L、催化剂NiFe₂O₄的用量为0.065 g、pH 2~10、在太阳光下照射480 min时,刚果红的降解率高达99%以上,催化剂性能稳定,适合处理刚果红类有机污染物。     

核壳结构p-n异质结复合光催化剂BiFeO3@TiO2的制备及其在可见光催化降解中的应用

化石燃料的迅速消耗导致环境污染与能源危机日益加剧.太阳能高效利用与转换是解决该难题的有效途径之一.在众多光催化剂中,TiO2因其高催化活性、高稳定性、低毒性以及低成本等优势而普遍受到关注,但TiO2存在着带隙过宽而无法利用可见光的缺陷,严重制约了其在光催化方向的实际应用.核壳型复合纳米材料具有较大的比表面积、较高的光吸收能力以及所吸附的污染物分子易于从吸附面扩散到光致降解面等特点,而表现出较强的有机污染物吸附性能以及良好的光催化活性.以磁体材料为核将TiO2包覆于磁体表面,可以制备具有磁分离特性的磁载光催化剂.而铁酸铋作为一种在室温下同时具有铁电性和铁磁性的钙钛矿型材料,由于其较窄的带宽(2.1 eV)在可见光催化氧化方面也受到了极大的关注.本文首先通过柠檬酸自燃烧法制备了可磁性分离的BiFeO3粉体,再以水解沉淀法将TiO2包裹在BiFeO3前驱体上形成了不同质量比(1:1,1:2,2:1)的核壳结构的BiFeO3@TiO2复合粉体,并以甲基紫为例,对其在紫外光和可见光照射下的光催化性能分别展开了研究.结果表明,BiFeO3@TiO2复合粉体的光催化性能较单独的BiFeO3或TiO2均有所提升.其中质量比为1:1的BiFeO3@TiO2复合粉体(TiO2壳层厚度为50–100 nm)展现出最强的光催化氧化活性,且在可见光下有更高的光催化效率.经表征分析,该复合粉体光催化性能高的原因可能归结于BiFeO3与TiO2两者之间形成了p-n异质结界面,有效地提高了电荷载流子的传输分离效率,同时BiFeO3较窄的禁带宽度拓展了纳米TiO2的光谱吸收范围,增强其光吸收能力.光电化学Mott-Schottky测试结果进一步证实:BiFeO3粉体在与TiO2复合之后,其电荷载流子传输与供体密度均有显著提升.自由基猝灭实验表明,在甲基紫光催化降解中起主要作用的为羟基自由基与光生电子,并结合能带理论与自建电场理论对降解机理进行了阐述.进一步研究表明,甲基紫降解效果最优条件为:复合粉体的投加量为1 g/L,甲基紫初始浓度为10 mg/L,初始pH为5.另外,质量比1:1的BiFeO3@TiO2对甲基橙和刚果红染料废水也具有较好的降解效果,表现出良好的工业应用前景.     

铝电极在LiNO3-KNO3熔盐中的电化学行为

采用循环伏安和恒电位电解法考察了铝电极在LiNO3-KNO3熔盐中的电化学行为. 实验结果表明, 在该熔盐中, 锂离子在铝电极上的电还原过程伴随着新生态的锂原子向电极内部的随后扩散步骤; 锂原子进入铝电极后与铝发生合金化, 形成β-LiAl合金和γ-LiAl合金; 锂离子在铝电极上的还原过程受还原态锂在铝基体内的扩散步骤控制. 循环伏安实验发现, 铝电极在该熔盐中的氧化和还原峰电流都先随循环次数增加而增大, 最后基本上趋于稳定. 这表明铝电极在该熔盐体系中具有较好的电化学稳定性.     

粒径可控的纳米铁酸铋的制备及其光催化性能

采用改进的聚丙烯酰胺凝胶法制备了BiFeO3纳米颗粒,利用热重-差热、红外光谱及X射线衍射等手段研究了干凝胶的热分解及BiFeO3的成相过程.结果表明,在600℃煅烧可制备出高纯的BiFeO3纳米颗粒.同时发现,随着双丙烯酰胺含量的增加,所得样品晶粒尺寸逐渐减小,从而制备出平均粒径约52～110nm的系列BiFeO3颗...     

La掺杂 BiFeO3对苯酚光催化降解性能的影响

苯酚是一种稳定、毒性大且难降解的有机物,对人类和生态环境产生很大威胁,因此急需研发出能有效移除工业废水中苯酚污染物的方法.其中,绿色、高效的光催化氧化技术得到研究人员青睐.在半导体光催化剂中, BiFeO3具有带隙窄(2.2–2.5 eV)、化学稳定性好及成本低等优点,被看作是最有潜力的光催化剂.但是, BiFeO3存在光生电子空穴对复合率高,制备过程中易形成杂质相的缺点,使得其光催化活性很差,限制了 BiFeO3在光催化领域的应用.异种离子的引入能产生杂质能级或裁剪半导体带隙,同时促进光生载流子分离,故可考虑采用离子掺杂改性 BiFeO3的手段来抑制杂质相生成,提高载流子分离,从而提高 BiFeO3的光催化性能.本文以柠檬酸为络合剂,通过一步溶胶凝胶法合成了系列样品 Bi1-xLaxFeO3(摩尔分数x =0,0.10,0.15,0.20).通过 X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射(UV-Vis DRS)及荧光光谱(PL)等手段对不同样品的物相、形貌、表面价态和光学性能进行了表征.并通过活性物种捕获实验和羟基自由基(?OH)产生实验分析了 Bi0.85La0.15FeO3样品在苯酚降解过程中的主要活性物种和降解机理.相对于单相 BiFeO3, La改性 BiFeO3催化剂的光降解苯酚性能均有提高,其中 La最佳掺杂量为0.15.在模拟太阳光下照射180 min后, Bi0.85La0.15FeO3的光催化活性达到96%,同时 COD去除率达到81.53%,并表现出好的循环使用活性和稳定性.研究发现,该光催化过程中主要的活性物种为?OH. XRD, SEM, TEM和 EDS结果表明, La元素掺杂进 BiFeO3结构中,且各元素分布均匀,同时,适量 La元素掺杂能有效抑制杂质相 Bi25FeO40的形成,而且 La掺杂 BiFeO3样品的颗粒尺寸略有减小,有利于电子空穴转移. XPS显示, La改性 BiFeO3样品的表面有氧空位形成,将有利于有机物的吸附和降解;另外,羟基氧和吸附氧含量增大,有利于活性氧物种形成. UV-Vis DRS和 PL测试证明, La改性后的样品对可见光的响应增强,样品带隙变窄,产生杂质能级,抑制了光生载流子复合,有利于产生更多载流子来促进活性物种形成,从而提高光催化活性.氧物种捕获实验说明,在 Bi0.85La0.15FeO3参与的苯酚降解过程中的主要活性物种是?OH,同时?OH的产生实验也证明了在光照下?OH在 Bi0.85La0.15FeO3光催化剂表面持续产生,并提出了光催化降解机理.     

可见光辐射下新型可循环石墨烯-铁酸铋杂化催化剂高效光催化降解氨氮

近年来,本课题组利用简单的一步水热法,将石墨烯和铁酸锰、铁酸镍进行掺杂,先后制备出石墨烯铁酸锰和活性炭铁酸镍纳米光催化材料,并发现在可见光辐射作用下,这两种光催化剂均能利用可见光能量催化分解过氧化氢产生活性因子,从而有效地降解氨.基于此,本文采用简单的水热法成功制备出新型的高效多相石墨烯铁酸铋(rG-BiFeO3)催化剂,并尝试在不添加H2O2的条件下进行光降解氨氮实验.结果表明,该复合光催化剂仍可接受可见光辐射,在rG和BiFeO3的协同作用下高效地光分解氨氮.由X射线衍射结果计算出rG-BiFeO3的平均粒径约为18.5 nm.通过清晰的rG-BiFeO3的透射电镜图可以观察到,BiFeO3纳米颗粒物较均匀地分散在rG的二维表面上.对比BiFeO3和rG-BiFeO3的傅里叶变换红外光谱可以发现,rG和BiFeO3之间可能形成了化学键.拉曼光谱结果表明,相对于纯的GO,rG-BiFeO3拉曼谱线的D带和G带发生了蓝移,表明石墨烯铁酸铋复合材料中的GO被充分还原成石墨烯.对比BiFeO3和rG-BiFeO3的紫外-可见漫反射光谱发现,rG-BiFeO3的漫反射光谱发生了红移,表明rG-BiFeO3光催化材料对可见光的响应程度进一步提高.比表面积测定表明,BiFeO3的比表面积为21.0 m2/g,而rG-BiFeO3催化剂的比表面积则增加到48.6 m2/g,说明rG-BiFeO3的吸附性能将得到很大提高.可见光催化反应结果表明,在不添加H2O2,pH=11的条件下,0.2 g rG-BiFeO3对50 mg/L NH3-N的降解率达到91.2%.动力学研究表明,BiFeO3光催化剂氧化氨氮反应遵循一级反应动力学规律.另外,由于BiFeO3纳米材料本身具有一定的弱磁性,所以BiFeO3和rG的复合材料也具有一定的磁性,较易回收.催化剂经过7次循环使用后,仍然具有很高的光催化活性.根据已有文献报道,吸附在催化剂表面的氨氮被氧化的路径有两条:(1)氨在被氧化为NH2,NH和N2Hx+y(x+y=0,1,2)等一系列中间产物后,最终被分解为氮气;(2)氨被氧化为中间产物HONH2,最终分解为硝酸盐和亚硝酸盐.本文利用紫外-可见分光光度计对rG-BiFeO3光降解体系下的氨溶液进行了全波长扫描,在206和211 nm处未检测到任何吸光度,从而排除了氨氮最终分解产物为硝酸盐和亚硝酸盐的可能性.这意味着rG-BiFeO3可见光降解氨体系符合第一种氧化路径.进一步的机理研究表明,反应过程中石墨烯与铁酸铋之间的协同作用所产生的空穴、超氧阴离子自由基和羟自由基共同将NH3直接氧化成N2,其中羟基自由基在整个氧化分解过程中起着最主要的作用.     

热分解双(2-氨基烟酸)锌(Ⅱ)制备的介孔微砖ZnO纳米颗粒的光催化活性(英文)

Hollow microblocks of [Zn(anic)_2], as a novel coordination compound, were synthesized using 2-aminonicotinic acid(Hanic) and zinc(Ⅱ) nitrate tetrahydrate. The chemical composition of the zinc complex, ZnC_(12)H_(10)N_4O_4, was determined by Fourier transform infrared(FTIR) spectroscopy and elemental analysis. The synthesized zinc complex was used as a precursor to produce ZnO nanostructures by calcination at 550 °C for 4 h. Morphological studies by scanning electron microscopy and transmission electron microscopy revealed the formation of porous microbricks of ZnO nanoparticles. N_2 adsorption-desorption analysis showed that the obtained ZnO microbricks possess a mesoporous structure with a surface area of 8.13 m~2/g and a pore size of 22.6 nm. The X-ray diffraction pattern of the final product proved the formation of a pure ZnO composition with a hexagonal structure. Moreover, FTIR analyses showed that the 2-aminonicotinic acid ligand peaks were absent after the calcination step. Diffuse reflectance spectroscopy was used to determine the band gap energy of the produced ZnO and it was about 3.19 eV. To investigate the photocatalytic activity of the porous ZnO nanostructure, a series of photocatalytic tests were carried out to remove Congo red, as a representative toxic azo dye, from aqueous solution. The results show that the product can be used as an efficient photocatalyst for waste water treatment with high degradation efficiency.     

Solvothermal Synthesis of Cs0.33WO3/LDHs Composite as a Novel Visible‐Light‐Driven Photocatalyst

A novel Cs_0.33WO₃/LDHs (CWLDH) composite was synthesized by simple two steps solvothermal method and first investigated as the photocatalyst for tetracycline (TC) and Congo red (CR) degradation under visible light irradiation. The CWLDH heterostructures catalysts were characterized by XRD, UV–Vis, SEM, XPS and BET. The composite CWLDH showed enhanced photocatalytic activity compared with pure Cs_0.33WO ₃ and NiAl‐LDH under identical experimental conditions. The enhanced photocatalytic activity was mainly attributed to the higher visible light‐absorbing ability, efficient electron–hole separation and prolonged lifetimes of photogenerated charges. The photocatalyst presented a high photocatalytic activity (92%) at the optimum of CWLDH ‐3 and initial TC concentration of 40 mg L⁻¹. Besides, the degradation efficiency of TC is higher than 75% for reused CWLDH after four cycles, demonstrating that it could be used as a potential catalyst with good photocatalytic activity, stability and reusability. According to the experimental results, a possible photocatalytic mechanism of CWLDH was discussed.     

高结晶氮化碳空心球的制备及其增强光催化产氢活性

石墨烯型氮化碳(g-C₃N₄)已经成为解决环境污染和能源危机问题的较为理想的光催化剂,但由于其较低的比表面积和较高的光生载流子重组效率而表现出较弱的光催化活性.因此,研究者们已经提出了许多策略,例如纳米结构设计,杂原子掺杂和增加结晶度,用来克服氮化碳的这些缺点,从而提高其光催化性能.其中,引起了较多关注的是增加g-C₃N₄的结晶度,因为晶化g-C₃N₄(CCN)的内层堆积密度高,外层结构缺陷少,可以提供更快的光生载流子迁移效率,从而增加参与光催化反应的光生电子和空穴.即便如此,通过常规方法制备的晶化g-C₃N₄依然显示出不规则的形貌和较低的比表面积.基于此,本文以氰尿酸-三聚氰胺(CM)超分子自组装混合物作为前驱体,通过熔盐法成功地制备了高结晶度的g-C₃N₄空心球(CCNHS).采用XRD、FTIR、13C固相CP-MAS NMR、XPS和时间分辨PL谱对CCNHS样品的基本性质进行了表征,并通过SEM、HRTEM、氮吸附-脱附和紫外-可见DRS光谱对CCNHS样品的形貌结构进行了表征.结果表明,CCNHS样品呈现出由纳米棒组成的非常规则的空心球结构,因而表现出比传统CCN样品更大的比表面积以及更强的光利用效率.CCNHS样品XRD谱出现晶化氮化碳的特征峰;其HRTEM照片出现了对应晶化氮化碳的0.33 nm晶格条纹;FFT衍射斑点的出现以及光吸收能力的增强进一步证明了CCNHS样品结晶度的提高.XPS谱元素分析以及EPR谱结果表明,CCNHS样品中还存在有利于提高光生电子转移的氮空位.光电流、阻抗谱以及与三嗪晶化氮化碳的对比结果证明,CCNHS样品中存在内在电场.同时,采用具有一定毒性的双酚A增塑剂替代了从粮食中提取出来的传统醇类牺牲剂,既保证了对有毒污染物的降解,也减少了粮食的浪费.即使以难降解的双酚A作为牺牲剂,CCNHS样品在降解双酚A(降解率为21%)的同时,依然表现出较好的光催化产氢活性(151.2μmol·h^?1·g^?1).本文为超分子自组装的结构优化以及晶化氮化碳的改善提供了新视角.     

L-丙氨酸在LiNO3, NaNO3, KNO3和NaClO4水溶液中的体积性质

利用Anton Paar DMA 55精密数字密度计测定了L-丙氨酸在LiNO₃, NaNO₃, KNO₃和NaClO₄水溶液中的密度, 计算了L-丙氨酸的表观摩尔体积、极限偏摩尔体积、迁移偏摩尔体积、理论水化数和体积作用系数. 根据静电相互作用和结构水合作用模型讨论了阴离子和阳离子对迁移偏摩尔体积的影响. 结果表明, L-丙氨酸在四种含氧酸盐水溶液中的迁移体积均为正值, 并且随着盐浓度的增大而增大. L-丙氨酸两性离子端基和阴阳离子间的静电作用对迁移体积的贡献是主要的. 静电作用削弱了两性离子带电中心对周围水分子的电致收缩效应, 造成了理论水化数随溶液浓度的增加而减小. L-丙氨酸在NaNO₃, KNO₃和NaClO₄水溶液中迁移体积的不同主要是由于静电作用的不同引起的, 在LiNO₃水溶液中迁移体积的“反常”是由于结构相互作用的影响较大所致.