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.     

1'-长链烷基取代吲哚啉螺苯并噻喃的合成及光谱性质

本文报道七个新的1'-长链烷基取代吲哚啉螺苯并噻喃衍生物的合成以及它们在溶液和高分子介质中的光致变色反应和吸收光谱性质。     

四中位（邻烷基）苯基卟啉及其高铁络合物的合成及光谱性质

合成了６种不同大小的烷基取代的四中位（邻烷基）苯基卟啉Ｔ＿（Ｏ－Ｒ）ＰＰＨ＿２及其高铁络合物Ｔ＿（Ｏ－Ｒ）ＰＰＦｅＣｌ（Ｒ＝ＣＨ＿３，Ｃ＿２Ｈ＿５，ｎ－Ｃ＿３Ｈ＿７，ｉ－Ｃ＿３Ｈ＿７，ｎ－Ｂｕ，ｔ－Ｂｕ），除Ｒ＝ＣＨ＿３外，其它５种是文献未曾报道过的新化合物。测定了它们的核磁共振谱、红外及电子光谱，并讨论了它们的结构与光谱性质的关系．     

粤北产五味子科植物风沙藤的化学成分研究I.

从粤北产五味子科植物风沙藤(Schisandra viridis A. C. Sm.)的根和茎中, 分到三个新的联苯环辛二烯木脂素化合物, 它们的结构和构型通过光谱分析和化学转变得以证实, 并分别命名为: 五脂酮(Schisanlignone)C(1), D(2)和五脂醇(schisan-lignaol)D(3)。     

Normal coordinate analysis of M-Si2H5-moieties in transition metal complexes and comparison to Br-Si2H5

In order to examine the influence of the transition metal on the metal-disilanyl-fragment and especially the M-Si and Si-Si-bond polarized Raman spectra of the complexes (C(5)R(5))(CO)(2)Fe-Si(2)H(5) {R=H ( 1a); R=Me ( 1b)} and (C(5)R(5))(CO)(2)(PMe(3))M-Si(2)H(5) {R=Me, M=Mo ( 2); R=H, M=W ( 3)} have been recorded. The spectral data have been evaluated and interpreted on the basis of a normal coordinate analysis of the M-SiH(2)-Si-fragment including Br-Si(2)H(5) ( 4) and comparison with examinations of the M-SiH(3)-fragment.     

N'-取代苯磺酰基N-(4,6-二取代均-三氮苯-2-基)乙二胺的合成

N-芳基磺酰乙二胺与三聚氰氯反应获得三个新缩合产物, 缩合产物再与醇钠反应得到六个N-取代苯磺酰基-N'-取代均三嗪基乙二胺衍生物, 所有化合物都表现出对植物生长的抑制作用, 可用于筛选除草剂.     

Diimine-acetylide compounds of ruthenium: the structural and spectroscopic effects of oxidation

The reaction of Ru(Me(2)bipy)(PPh(3))(2)Cl(2) 1 with terminal alkynes HCCR in the presence of TlPF(6) leads to the formation of the vinylidene compounds [Ru(Me(2)bipy)(PPh(3))(2)Cl(=C=CHR)][PF(6)] (2) (2a, R = Bu(t); 2b, R = p-C(6)H(4)-Me; 2c, R = Ph). These compounds decompose in oxygenated solution to form the carbonyl compound [Ru(Me(2)bipy)(PPh(3))(2)Cl(CO)][PF(6)] (3), and may be deprotonated by K(2)CO(3) to give the ruthenium(II) terminal acetylide compounds Ru(Me(2)bipy)(PPh(3))(2)Cl(CC-R) (4) (4a, R = Bu(t); 4b, R = p-C(6)H(4)-Me; 4c, R = Ph). Cyclic voltammetry shows that 2a-c may also be reductively dehydrogenated to form 4a-c. 4a-c are readily oxidized to their ruthenium(III) analogues [4a](+)-[4c](+), and the changes seen in their UV/visible spectra upon performing this oxidation are analyzed. These show that whereas the UV/visible spectra of 4a-c show MLCT bands from the ruthenium atom to the bipyridyl ligand, those of [4a](+)-[4c](+) contain LMCT bands originating on the acetylide ligands. This is in agreement with the IR and ESR spectra of [4a](+)-[4c](+). The X-ray crystal structures of the redox pair 4a and [4a][PF(6)()] have been determined, allowing the bonding within the metal-acetylide unit to be analyzed, and an attempt is made to determine Lever electrochemical parameters (E(L)) for the vinylidene and acetylide ligands seen herein. Room temperature luminescence measurements on 4a-c show that the compounds are not strongly emissive.     

取代四甲基环戊二烯基钌羰基化合物的合成及晶体结构(英文)

The ligands (C5Me4R) [R =n-Butyl (1), Benzyl (2), PhMe-2 (3)] reacted with Ru3(CO)12 in refluxing xylene to give corresponding new substituted tetramethylcyclopentadienyl diruthenium metal carbonyl complexes [(η5-C5Me4R)Ru(CO)( μ-CO)]2 [R=n-Butyl (4), Benzyl (5), PhMe-2 (6)], respectively. The three new complexes were characterized by elemental analysis, IR and 1H NMR spectra. The crystal structure of complex 5 was determined by single crystal X-ray diffraction. The X-ray crystal structure of complex 5 confirms the structure with bridging and terminal CO groups. CCDC: 709601.     

Synthesis, X-ray diffraction studies, and DFT calculations on hexacoordinated germanium derivatives: the case of germaspirobis(ocanes)

Synthesis of the title compounds, viz. [RN(CH2CHR'O)2]2Ge (1, R = Me, R' = H; 2, R = Me, R' = Ph; 3, R = Ph, R' = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH2CHR'OH)2 (4, R = Me, R' = H; 5, R = Me, R' = Ph; 6, R = Ph, R' = H) with (AlkO)4Ge is reported. Composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy and mass spectrometry as well as elemental analysis data. The single-crystal X-ray diffraction of 2 has clearly indicated the presence of two transannular interactions Ge<--N in the compound. N atoms are cis-orientated. The compound 3 possesses long Ge...N distances. The structural data obtained from geometry optimizations by DFT calculations on 1-3 reproduces experimental results. Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically stable for all three compounds. The transition states for possible cis <--> trans rearrangement processes in 1-3 were calculated. The properties of the Ge-O and Ge<--N bonds in 1-3 were analyzed by the AIM approach. The interactions between the Ge atom and N atoms as well as O atoms possess predominantly ionic character.     

Synthesis and Characterization of Ferrocene Derived Cyclic Carbaphosphazenes

Dialkylamino substituted cyclic carbaphosphazenes, (R 2 NCN) 2 (NPCl 2 ) were prepared and reacted with the ferrocene derived hydroxymethyl phosphine sulfide FcCH(CH 3 )P(S)(CH 2 OH) 2 after dilithiation to yield a series of new spirocyclic derivatives of cyclic carbaphosphazenes having ferrocenyl pendant groups. To confirm the formation of six membered spirocycles and to compare their spectral features, transesterification reactions of FcCH(CH 3 )P(S)(CH 2 OH) 2 also were carried out with P(NR 2 ) 3 , yielding the six membered heterocycles FcCH 2 P(S)(CH 2 O) 2 PNR 2 (R = Me, Et). The compounds were characterized by 1 H, 31 P, 13 C NMR, mass spectra, and elemental analysis.     

Synthesis and characterization of tetrahedral and square planar Bis(iminopyrrolyl) complexes of cobalt(II)

A series of 2-iminopyrrole ligand precursors with increasing bulkiness [HNC4H3C(R)=N-2,6-R'2C6H3] (R = R' = H, 1a; R = Me, R'= H, 1b; R = H, R' = Me, 1c; R = R' = Me, 1d; R = H, R' = iPr, 1e; R = Me, R' = iPr, 1f) were synthesized and deprotonated with NaH to give the corresponding iminopyrrolyl sodium salts 2a-f. A set of homoleptic bis-ligand Co(II) complexes of the type [Co(kappa2N,N'-NC4H3C(R)=N-2,6-R'2C6H3)2] (R = R'= H, 3a; R = Me, R'= H, 3b; R = H, R' = Me, 3c; R = R' = Me, 3d; R = H, R' = iPr, 3e; R = Me, R' = iPr, 3f) was prepared by reaction of CoCl2 with the corresponding iminopyrrolyl sodium salts 2a-f. The new complexes were characterized by elemental analysis, magnetic susceptibility measurements, in powder and in solution, UV/vis/NIR, and, in some cases, X-ray crystallography. According to X-ray diffraction and magnetic measurements, the Co complexes 3a-e proved to be tetrahedral, which is the preferred geometry for Co(II) compounds. However, a square planar geometry is observed in the case of 3f, as determined by several characterization techniques. In this case, DFT calculations suggest the square planar geometry is slightly more stable than the tetrahedral one probably due to a combination of steric and electronic reasons.