Construction and Analytical Applications of Plastic Membrane Electrodes for Oxytetracycline Hydrochloride

 Oxytetracycline hydrochloride-selective electrodes of both the coated wire and the conventional polymer membrane types based on oxytetracyclinium phosphotungstate and phosphomolybdate have been prepared. A Nernstian response is shown by these electrodes within 1.0×10⁻⁶–1.0×10⁻² M concentration ranges depending on the type of electrode. The response is unaffected by the change of pH over the range 4–11. The standard electrode potentials, E°, were determined at different temperatures and used to calculate the isothermal temperature coefficients of the electrodes. The electrodes show good selectivity to oxytetracycline hydrochloride with respect to many inorganic cations, sugars and amino-acids. Oxytetracycline hydrochloride is determined successfully in pure solutions and in pharmaceutical preparations using calibration by standard addition and potentiometric titration. A regeneration process for the exhausted electrodes has been developed. Received February 2, 2000. Revision April 7, 2000.     

Halide‐Based Materials and Chemistry for Rechargeable Batteries

Rechargeable batteries are considered one of the most effective energy storage technologies to bridge the production and consumption of renewable energy. The further development of rechargeable batteries with characteristics such as high energy density, low cost, safety, and a long cycle life is required to meet the ever‐increasing energy‐storage demands. This Review highlights the progress achieved with halide‐based materials in rechargeable batteries, including the use of halide electrodes, bulk and/or surface halogen‐doping of electrodes, electrolyte design, and additives that enable fast ion shuttling and stable electrode/electrolyte interfaces, as well as realization of new battery chemistry. Battery chemistry based on monovalent cation, multivalent cation, anion, and dual‐ion transfer is covered. This Review aims to promote the understanding of halide‐based materials to stimulate further research and development in the area of high‐performance rechargeable batteries. It also offers a perspective on the exploration of new materials and systems for electrochemical energy storage.     

An insight into the self-discharge of Fe3O4 electrodes in alkali solutions

Iron oxide development is necessary as the Iron electrodes exhibit high self discharge and poor charging efficiency in alkaline batteries. Pressed electrodes containing electrolytic iron powder with varying amounts of Fe₃O₄ have been used. The variation of open circuit potential and self discharge currents with alkali concentration is followed. For better understanding of these variations, cyclic polarisation (−1.3 V to + 0.4 Vvs Hg/HgO) and hydrogen evolution studies are carried out. Beyond −0.5 Vvs Hg/HgO, the surface is covered by hydrolysed layer and the protons diffuse away from this layer. The hydrogen evolution takes place with the discharge of K⁺ ions as the rate determining step.     

Intercalation materials for lithium rechargeable batteries

An overview is given of intercalation materials for both the negative and the positive electrodes of lithium batteries, including the results of our own research. As well as lithium metal as a negative electrode, we consider insertion materials based on aluminium alloys. In the case of the positive electrode metal-oxides based on manganese, nickel and cobalt are discussed. Received: 27 May 1997 / Accepted: 30 July 1997     

Chain engineering-tailored microstructures and lithium storage performance of hydrothermally-synthesized linear polyimides

Polyimides with high capacity, fast kinetics, abundant resource, and structural diversity offer an exhilarating opportunity for developing sustainable rechargeable batteries. Herein, a series of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA)-based polyimides were successfully crafted through a facile and eco-friendly hydrothermal synthesis route. The microstructure and lithium storage performance of polyimides were tailored by regulating diamine linkers between NTCDA units. Interestingly, the moderate increased length of flexible diamine units with ethylenediamine and diaminobutane can stabilize the polymer skeleton. This leads to the formation of honeycomb-like porous structures with a sufficient exposure of active carbonyl groups, thereby achieving a large capacity and high rate capability. Therefore, polyimides derived from ethylenediamine and diaminobutane show larger reversible capacities (123 and 113.5 mA h/g at 50 mA/g, respectively) and better rate capabilities with capacity retentions of up to 50% when the current increased from 50 to 2000 mA/g. This work would provide new insights into macromolecular engineering of polymers for advanced electrode materials.     

Ion-selective electrodes for determination of phenylalanine based on uranyl complexes of phosphoryl-containing podands

The possibility of phenylalanine determination using membrane ion-selective electrodes based on uranyl complexes with phosphoryl-containing podands was shown. The variation of the procedure of membrane preparation (either entrapping the preliminarily synthesized uranyl-podand complex in the membrane phase or conditioning of the podand-containing membrane in the uranyl solution) was found to have practically no effect on the electrode properties. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1729–1732, October, 2000.     

Studies of electrochemical behaviour of RuO2-PVC film electrodes: dependence on oxide preparation temperature

Ruthenium dioxide electrodes, prepared on a Pt substrate using coatings of PVC-RuO₂ mixed in THF (designated as RuO₂-PVC film electrode) have been studied for their redox behaviour in 1 M NaOH using variable scan cyclic voltammetry. The various redox transitions in the oxidation state of the central metal ion are characterized using electrochemical parameters such as peak potential, peak current, and surface charge. The effect of oxide preparation temperature, in the range 300–700 °C, on the redox characteristics has also been studied and correlated with the electrochemically active surface area (as measured using small amplitude cyclic voltammetry) and the true surface area (by the BET method). Received: 12 August 1997 / Accepted: 18 October 1999     

Electrochemical properties of silver–copper alloy microelectrodes for use in voltammetric field apparatus

Microelectrodes of silver–copper alloys have been evaluated for use in voltammetric analyses. Increased overpotential towards the hydrogen overvoltage reaction (HER) was found as a function of increased copper content in the silver. A study of oxidizing products by cyclic voltammetry (CV) in NaOH solution showed ten anodic and eight cathodic peaks which are described in the present paper. The behaviour of these alloy electrodes is somewhere between pure silver and pure copper electrodes. Differential pulse anodic stripping voltammetry (DPASV) was used to measure zinc, cadmium and lead in ultrapure water only (18 MΩcm), and good linearity was found for all metals (r ²=0.998) in the range of 0.5 to 5 ppb with a 600- to 1,200-s plating time. It was additionally found that cadmium and lead were better separated on the alloy electrodes compared to pure silver electrodes. Measurements of nickel were carried out on alloy electrodes by use of adsorptive differential pulse cathodic stripping voltammetry (Ad-DPCSV), and good linearity (r ²=1.000) was found in the range from 0.5 to 5 ppb with an adsorption time of 120 s. The alloy electrodes were also found to be sensitive to nitrate, and good linearity (r ²=0.997) was found in the range from 1 mg L⁻¹ to 100 mg L⁻¹ using differential pulse voltammetry (DPV) scanning from −450 mV to −1,500 mV. Addition of nitrate in ultrapure water afforded two different peaks related to the successive reductions of nitrate and nitrite. In ammonium buffer solution (pH 8.6) only one peak resulting from reduction of nitrate was observed. Furthermore, the use of alloy electrodes containing 17% Cu was tested in real samples, by installing it in a voltammetric system for monitoring of zinc and lead in a polluted river, the river Deûle, near the town of Douai in northern France. Results were found to be in agreement with parallel measurements carried out by ICP-MS.     

The potentiometric behavior of polymer-supported metallophthalocyanines used as anion-selective electrodes

Liquid polymer membrane electrodes based on nickel and manganese phthalocyanines were examined for use as anion-selective electrodes. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes, which were directly coated onto the surfaces of graphite electrodes. The resulting electrodes demonstrate near-Nernstian responses over a wide linear range of perchlorate anion (5 × 10⁻⁷ to 1 × 10⁻¹ M). The electrodes have a fast response time, submicromolar detection limits (5 × 10⁻⁷ M perchlorate), and could be used over a wide pH range of 3.5–10. The influences of lipophilic cationic and anionic additives on the response properties of the electrodes were investigated. The proposed sensors revealed high selectivity for perchlorate over a number of common inorganic and organic anions. The highest selectivity was observed for the electrode based on manganese phthalocyanine in the presence of the lipophilic anionic additive sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. Application of the electrodes to determine perchlorate in tap water and human urine is also reported.      

Development of membrane electrodes for selective determination of some antiepileptic drugs in pharmaceuticals,plasma and urine

Newly developed, simple, low-cost and sensitive ion-selective electrodes have been proposed for determination of some antiepileptic drugs such as lamotrigine, felbamate, and primidone in their pharmaceutical preparations as well as in biological fluids. The electrodes are based on poly(vinyl chloride) membranes doped with drug–tetraphenyl borate (TPB) or drug–phosphotungstic acid (PT) ion-pair complexes as molecular recognition materials. The novel electrodes displayed rapid Nernstian responses with detection limits of approximately 10⁻⁷ M. Calibration graphs were linear over the ranges 5.2 × 10⁻⁷–1.0 × 10⁻³, 1.5 × 10⁻⁶–1.0 × 10⁻³, and 2.6 × 10⁻⁷–1.0 × 10⁻³ M for drug–TPB and 5.8 × 10⁻⁷–1.0 × 10⁻³, 1.8 × 10⁻⁷–1.0 × 10⁻³, and 6.6 × 10⁻⁷–1.0 × 10⁻³ M for drug–PT electrodes, respectively, with slopes ranging from 52.3 to 62.3 mV/decade. The membranes developed have potential stability for up to 1 month and proved to be highly selective for the drugs investigated over other ions and excipients. The results show that the selectivity of the ion-selective electrodes is influenced significantly by the plasticizer. The proposed electrodes were successfully applied in the determination of these drugs in pharmaceutical preparations in four batches of different expiry dates. Statistical Student’s t test and F test showed insignificant systematic error between the ion-selective electrode methods developed and a standard method. Comparison of the results obtained using the proposed electrodes with those found using a reference method showed that the ion-selective electrode technique is sensitive, reliable, and can be used with very good accuracy and high percentage recovery without pretreatment procedures of the samples to minimize interfering matrix effects. Figure Structure of lamotrigine, felbanate and primidone     

Carbon paste electrodes: correlation between the electrochemical hydrogen storage capacity and the physicochemical properties of carbon blacks

The difficulties in the use of carbon paste electrodes to quantify the electrochemical adsorption of hydrogen in nanocarbon materials are described. Chronoamperometry studies using a Ferro/Ferri redox couple were performed to obtain the electrochemical active area of paste electrodes prepared by dispersion of differing samples of carbon blacks (CB) within silicon oil. This electrochemical active area was combined with the BET-surface area of the carbon blacks, to obtain the mass of superficial carbon involved in the electrochemical processes. To assure equal conditions for comparison, the electronic conductivity of the paste was equivalent in all the samples. From our results it appears that cyclic voltammetry, combined with carbon paste electrodes and nitrogen adsorption isotherms, provides a simple and less expensive route for the qualitative evaluation of the electrochemical hydrogen uptake of novel carbon materials. Still, for quantitative measurements, some issues remain unsolved in highly structured carbons, where the lack of penetration of the bulky Ferro/Ferri redox couple in the micropores of the CB and the occurrence of solid-state diffusion cause the underestimation of the mass involved in hydrogen adsorption.     

Aligned carbon nanostructures based 3D electrodes for energy storage

Electrochemical energy storage systems with high specific energy and power as well as long cyclic stability attract increasing attention in new energy technologies. The principles for rational design of electrodes are discussed to reduce the activation, concentration, and resistance overpotentials and improve the active material efficiency in order to simultaneously achieve high specific energy and power. Three dimensional(3D)nanocomposites are currently considered as promising electrode materials due to their large surface area,reduced electronic and ionic diffusion distances, and synergistic effects. This paper reviews the most recent progress on the synthesis and application of 3D thin film nanoelectrode arrays based on aligned carbon nanotubes(ACNTs) directly grown on metal foils for energy storages and special attentions are paid on our own representative works. These novel 3D nanoelectrode arrays on metal foil exhibit improved electrochemical performances in terms of specific energy, specific power and cyclic stability due to their unique structures.In this active materials coated ACNTs over conductive substrate structures, each component is tailored to address a different demand. The electrochemical active material is used to store energy, while the ACNTs are employed to provide a large surface area to support the active material and nanocable arrays to facilitate the electron transport. The thin film of active materials can not only reduce ion transport resistance by shortening the diffusion length but also make the film elastic enough to tolerate significant volume changes during charge and discharge cycles. The conductive substrate is used as the current collector and the direct contact of the ACNT arrays with the substrate reduces significantly the contact resistance. The principles obtained from ACNT based electrodes are extended to aligned graphene based electrodes. Similar improvements have been achieved which confirms the reliability of the principles obtained. In addition, we also discuss and view the ongoing trends in development of aligned carbon nanostructures based electrodes for energy storage.     

钠离子电池电极材料研究进展

室温钠离子电池由于原料丰富,分布广泛,价格低廉,引起了人们的研究兴趣。然而,由于钠离子相对于锂离子较重且半径较大,这会限制钠离子在电极材料中的可逆脱嵌过程,从而影响电池的电化学性能。因此研发先进的电极材料成为钠离子电池实用化的关键。本文中我们主要介绍了几种典型的钠离子电池电极材料,并对其最新的研究进展进行了简要综述,将为钠离子电池新型电极材料的研究提供基础。     

钠离子电池电极材料研究进展

室温钠离子电池由于原料丰富,分布广泛,价格低廉,引起了人们的研究兴趣。然而,由于钠离子相对于锂离子较重且半径较大,这会限制钠离子在电极材料中的可逆脱嵌过程,从而影响电池的电化学性能。因此研发先进的电极材料成为钠离子电池实用化的关键。本文中我们主要介绍了几种典型的钠离子电池电极材料,并对其最新的研究进展进行了简要综述,将为钠离子电池新型电极材料的研究提供基础。     

Ti3C2Tx MXene compounds for electrochemical energy storage

Since their discovery in 2011, MXene compounds, and in particular the Ti₃C₂-based phases, have gained increasing interest from researchers leading to over 2000 scientific works in 2020. The peculiar morphological, charge transport, and surface properties make the MXenes ideal materials for energy storage applications such as active material in alkaline ion batteries and supercapacitors, as conductive or buffer agent in composite electrodes for high energy applications, and as electrocatalytic materials for oxygen evolution or redox flow batteries. Among this almost endless literature, this work focuses on 5 recent articles (2019/2020) that summarize the potential of MXenes in different energy storage applications, also resuming the most promising preparatory routes regarding industrial scalability.     

Economic bismuth-film microsensor for anodic stripping analysis of trace heavy metals using differential pulse voltammetry

Stripping analysis has been widely recognised as a powerful tool in trace metal analysis. Its remarkable sensitivity is attributed to the combination of a preconcentration step coupled with pulse measurements that generate an extremely high signal-to-background ratio. Mercury-based electrodes have traditionally been used to achieve high reproducibility and sensitivity in the stripping technique. Because of the toxicity of mercury, however, new alternative electrode materials are highly desired, particularly for on-site monitoring. Use of thin films of bismuth deposited on platinum or glassy-carbon substrates has recently been proposed as a possible alternative to mercury—bismuth is “environmentally friendly”, of low toxicity, and is in widespread pharmaceutical use. In this paper the preparation of economic bismuth-film microelectrodes by electrodeposition on a copper substrate and their application to heavy metal analysis are described. Bismuth-film electrodes were prepared by potentiostatic electrodeposition. Optimum conditions for chemical and electrochemical deposition to obtain an adherent, reproducible, and robust deposit were determined. The suitability of such microelectrodes for analysis of heavy metals was evaluated by anodic stripping voltammetry of cadmium. The analytical performance of bismuth-film electrodes for anodic stripping voltammetry of heavy metals was evaluated for non-deaerated solutions containing Cd²⁺, Pb²⁺, and Zn²⁺ ions. Well-defined peaks with low background current were obtained by use of differential pulse voltammetry. Linear calibration plots were obtained for Cd²⁺ in acidified tap water at concentrations ranging from 2×10⁻⁸ to 1×10⁻⁷ mol L⁻¹ and from 1×10⁻⁷ to 1×10⁻⁶ mol L⁻¹ with relative standard deviations of 5% (n=15) at the 1×10⁻⁷ mol L⁻¹ level. The method was then successfully used to monitor the Cd²⁺content of plant extracts and validated by polarographic and ICP−MS measurements. These results open the possibility of using bismuth-coated copper electrodes as an alternative to mercury-based electrodes for analysis of heavy metals. The main problem remaining, which prevents on-site monitoring of heavy metals, is the need to use slightly acidic media, because formation of bismuth hydroxide on the film surface above pH 4.3 leads to non-reproducible measurements. Further experiments will be performed to discover whether electrode conditioning can be used to enable reproducible measurement in on-site monitoring of cadmium in natural waters. Moreover, further study should be conducted to evaluate the potential of BiFE for analysis of several pollutants of interest that are usually determined electrochemically by using mercury-based electrodes. Presented at the 9th FECS Conference on Chemistry and the Environment, Bordeaux , 29 August to 1 September, 2004     

A copper ion-selective electrode with high selectivity prepared by sol-gel and coated wire techniques

A sol-gel electrode and a coated wire ion-selective poly(vinyl chloride) membrane, based on thiosemicarbazone as a neutral carrier, were successfully developed for the detection of Cu (II) in aqueous solutions. The sol-gel electrode and coated electrode exhibited linear response with Nernstian slopes of 29.2 and 28.1 mV per decade respectively, within the copper ion concentration ranges 1.0×10^–5–1.0×10^–1 M and 6.0×10^–6–1.0×10^–1 M for coated and sol-gel sensors. The coated and sol-gel electrodes show detection limits of 3.0×10^–6 and 6.0×10^–6 M respectively. The electrodes exhibited good selectivities for a number of alkali, alkaline earth, transition and heavy metal ions. The proposed electrodes have response times ranging from 10–50 s to achieve a 95% steady potential for Cu²⁺ concentration. The electrodes are suitable for use in aqueous solutions over a wide pH range (4–7.5). Applications of these electrodes for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu²⁺ ion using EDTA, are reported. The lifetimes of the electrodes were tested over a period of six months to investigate their stability. No significant change in the performance of the sol-gel electrode was observed over this period, but after two months the coated wire copper-selective electrode exhibited a gradual decrease in the slope. The selectivity of the sol-gel electrode was found to be better than that of the coated wire copper-selective electrode. Based on these results, a novel sol-gel copper-selective electrode is proposed for the determination of copper, and applied to real sample assays.     

基于有机物电极的电化学能量存储与转化

由于高安全的特性,水系二次电池被认为是未来大型储能的有效解决方案之一. 然而,现有水系电池主要以含金属元素的无机化合物为电极活性材料,其在大型储能中的实际应用仍受到循环寿命、环境问题、原料成本或金属元素丰度的限制. 相较于无机电极材料,部分有机电极材料具有原料丰富、结构丰富、可持续及环境友好等优点. 此外,有机物材料分子内空间大,能够存储不同价态电荷,因此近年来被广泛关注. 本文综述了课题组近期在有机物电极方面的研究进展,内容聚焦含羰基有机物通过C=O/C-O-的可逆转化存储单价金属阳离子(Li⁺, Na⁺)、双价金属阳离子(Zn²⁺)、质子(H⁺)所涉及的电化学过程,及其在水系锂、钠离子电池、水系锌离子电池、质子电池以及分步电解水中的应用.     

Paper like free-standing hybrid single-walled carbon nanotubes air electrodes for zinc–air batteries

Flexible electrode architectures based on non-functionalized (P2) and functionalized (P3) single-walled carbon nanotubes (SWNTs) were fabricated via a simple vacuum filtration process. A hybrid layer of various compositions of P2- and P3-SWNTs forms free-standing membranes (~80 μm in thickness), and their electrochemical performance was evaluated as an air electrode AEP_2/P3 in zinc–air batteries. Such bifunctionalized air electrodes showed uniform surface morphology with interconnected micron-sized porous structure with high porosity (~70%). The N₂ adsorption isotherms at 77 K are of type IV with BET-specific surface areas of AE_(60/40) and AE_(80/20) to be 130.54 and 158.76 m² g⁻¹, respectively, thus facilitates high active surface area for active oxygen reduction/evolution reactions. BJH pore size distribution of AE_(60/40) and AE_(80/20) shows maximum pores with diameter <15 nm. The zigzag interlaying of the SWNTs imparts mechanical stability and flexibility in zinc–air batteries. Zinc–air batteries with optimized compositions of P2- and P3-SWNTs in air electrode AE_(60/40) had ionic conductivity ~1 × 10⁻² S cm⁻¹ and delivered higher discharge capacity ~300 mAh g⁻¹ as compared to AE_(80/20) composition. The unique properties of AE_(P2/P3) studied in this work would enable flexible air electrode architectures in future metal–air batteries.     

金属氢化物电极的化学活化

通过对Mm（NiMnCoAl）5电极的化学活化处理提高了金属氢化物电极的容量、电催化活性、活化性能和快速放电能力；讨论了化学活化处理对金属氢化物电极电化学性能的影响；在活化剂KBH4作用下，金属氢化物表面的氧化物技还原，在活化过程中一部分氢原子贮入合金之中，增加了电极的比表面，文中试验了这种活化方法对Ni／MH电池封口化成的作用，测试结果表明封口化成的AA型Ni-MH电池性能与开口化成电池的性能相当，其容量达到1050～1150mAh，1C、3C、SC信率下放电容量分别达到0．2C下的96．7％、89．0％、83．8％