Electrochemical Analysis Methods Research Articles

Nano solid phase micro membrane tip and electrochemical methods for vanillin analysis in chocolate samples

A polymer-based nanosensor and electrochemical methods were developed for the quantitative analysis of vanillin. The sample preparation was done using nano solid phase micro membrane tip extraction (NSPMMTE). A novel poly(phenylalanine)/TiO2/CPE sensor was built as the working electrode for the first time for the analysis of the vanillin substance. The electrochemical behavior and analytical performance of vanillin were examined in detail by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) techniques via the oxidation process. The optimized modules of the DPSV technique that affected the vanillin peak current and peak potential were pH, pulse amplitude, step potential, and deposition time. The electroactive surface areas of bare CPE, TiO2/CPE, and poly(phenylalanine)/TiO2/CPE electrodes were found to be 0.135 cm2, 0.155 cm2, and 0.221 cm2, respectively. The limit of detection (LOD) was 32.6 μg/L in the 0.25–15.0 mg/L working range at pH 7.0. The selectivity of the proposed DPSV method for the determination of vanillin on the modified electrode was investigated in the presence of various organic and inorganic substances, and the determination of vanillin with high recovery was achieved with less than 5% relative error. The analytical application was applied in chocolate samples and the DPSV method was found highly efficient, reproducible, and selective.

An electrochemical sensing platform for biomonitoring the potential toxicity of plastic particles by detecting NO

Plastic particles are common pollutants in our daily lives and cause a range of potential toxicities when ingested by living organisms. However, the complex morphology of plastic particles in the natural environment makes it difficult to assess their potential toxicity using conventional ecological monitoring techniques. Therefore, we constructed an electrochemical sensor based on gold/multi-wall carbon nanotube-Fe(III) meso-tetra (4-carboxyphenyl) porphyrin/Nafion (Au/MWCNT-FeTCP/Nafion) composite material to evaluate the potential toxicity of plastic particles through the detection of nitric oxide (NO). The sensor exhibited good catalytic performance for NO with a linear relationship within 0.1–––0.7 μmol/L and 0.8–––5 μmol/L and a detection limit of 0.08 μM. We used this sensor to evaluate the changes in NO released by cells and tissues exposed to polystyrene (PS) plastic particles which showed that as the concentration of PS incubated with cells increased and the incubation time prolonged, the level of NO released by cells also increased. Notably, we combined immunofluorescence, immunoblotting, and electrochemical analysis methods simultaneously to reveal the cellular signaling pathway of NO production and apoptosis induced by PS. Furthermore, the effectiveness of the sensor in biomonitoring the oxidative damage of PS plastic particles on NO was further verified at the tissue level by constructing a mouse model treated with PS plastic particles. The sensor presented here offers a promising approach to study the biotoxicity of plastic particles and may contribute to the development of novel solutions for mitigating their hazardous effects on the human health.

Fe Single-Atom Nanozymes for Real-Time Dual Monitoring of H2O2 Released from Living Cells

Excessive accumulation of hydrogen peroxide (H2O2) in the physiological pool can cause oxidative stress of cells and eventually lead to the occurrence of diseases. Therefore, accurate and real-time detection of H2O2 is of great significance for disease detection and prevention. In this study, an Fe single-atom nanozyme (Fe-SNC) with an Fe-N4 active center was synthesized, which showed excellent peroxidase-like activity in an acidic environment and amazing electrocatalytic activity in H2O2 reduction reaction. Based on this, we proposed a colorimetric and electrochemical dual-signal detection strategy to real-time monitor H2O2 secreted by living cells. Compared with single-signal response mode, double-signal response mode has higher precision and sensitivity. The results show that the detection range of the colorimetric analysis method is 3–1000 μM and the detection limit is 1.3 μM. The detection range of the electrochemical analysis method is 1–8127 μM, and the detection limit is 0.61 μM. We believe that the dual-signal detection strategy based on Fe-SNC not only provides a way for the ultra-sensitive detection of hydrogen peroxide but also has a broad application prospect in clinical diagnosis.

APPLICATION OF MOLYBDENUM-BASED BIOSENSORS IN THE DIAGNOSIS OF DISEASES

Molybdenum transition metal compounds and nanoparticles have attracted much attention due to their unique physicochemical properties, multifunctional properties, and increased technological applications. This literature review reviewed the work of molybdenum compound biosensors based on research conducted over the past five years. Biosensors are analytical devices that combine a biological component and a physico-chemical component to produce a measured signal. In the course of the literature review, it was found that molybdenum-based biosensors were used to determine troponin-I, chronic myeloid leukemia, cyclic citrulline peptide, acetaminophen, Tau-381, dopamine, and epithelial cell adhesion molecules. It was found that these sensitive biomarkers are very effective for diagnosis, predicting the rate of development of the disease and rehabilitation, evaluating pharmacological treatment - one of the main obstacles in the study of diseases such as acute myocardial infarction, arthritis, cancer and Alzheimer's disease. As a result of the considered scientific works, such basic parameters of molybdenum-based biosensors as the detection limit relative to synthesis methods, electrochemical analysis methods, specificity, and the analysis under study were compared in tabular form. In general, the main purpose of this review is to conduct an analysis and a comprehensive review of the research work of molybdenum and its compounds used in the creation of a biosensor.

Electrochemical Corrosion Behavior of 310S Stainless Steel in Hot Concentrated Tap Water

The corrosion behavior of 310S stainless steel was investigated in synthetic tap water and Ca2+ and Mg2+-free solutions with different concentration ratios at 80 °C using electrochemical measurement techniques and surface analysis methods. The main purpose was to obtain the electrochemical corrosion characteristics under carbonate scale conditions. The specimens displayed a spontaneous passivation state in the solutions with or without Ca2+ and Mg2+ ions. With the enlargement of the concentration ratio of synthetic tap water from 1 to 10 times, the polarization resistance under free corrosion conditions and the pitting potential decreased by about 48% and 327 mV, respectively. The pitting tendency increased with increasing concentration ratio of tap water. The carbonate scales deposited from the synthetic tap water solutions were mainly composed of CaCO3, which led to a slight increase in the polarization resistance and the pitting potential and decrease in the passive current density.

Fourier transform voltammetric studies of single nanoparticles transition impacts at the micro-liquid/liquid interface

Fourier transform large-amplitude sinusoidal voltammetry (FTSV) is applied to study the single nanoparticle transition impacts at micro-liquid/liquid interface. Through short-time Fourier transform, the current response signal of platinum nanoparticles colliding on the liquid/liquid interface of micro tubes was first deducted in time domain and frequency domain, and the single-period sinusoidal voltammetry curve and the first harmonic phase angle were separated, respectively. The results show that for platinum nanoparticles with different sizes, the first harmonic phase angle of the current response signal has no obvious monotonic relationship with the particle size, but varies about ± 25° with the difference of the particle zeta potential. Then, platinum and gold nanoparticles with similar size were studied simultaneously, and the first harmonic phase angles of their collision signals were distributed in different regions, which can be identified and detected. The further studies reveal that the mechanism was root in their different permittivity. This work solves the problem of low signal-to-noise ratio within the potential window by applying a potential with large amplitude, and tries to find out the relationship between electrochemical responses and the electrostatic properties of single nanoparticles by single transition impacts. This study has a promising application in the establishment of a highly sensitive and selective electrochemical analysis method based on the liquid/liquid interface.

Calcium-doped TiO2 microspheres and near-infrared carbazole-based sensitizer for efficient co-sensitized dye-sensitized solar cell

Here, we synthesized metal-free organic dye (CCPICPB) with two carbazole donor groups and two anchoring groups that exhibit a panchromatic absorption in the near-infrared range of up to 750 nm. To study the photophysical properties of synthesized CCPICPB dye, the UV–Vis and cyclic voltammetric experiments were studied and the obtained results were validated with theoretical simulation studies. After that, the solvothermal approach is used to synthesize pristine anatase and calcium (Ca)-doped TiO2 microspheres with a smooth morphology. These microstructures are examined in depth using XRD, electron microscopy and electrochemical analysis methods. On TiO2 and Ca-doped TiO2 photoanode materials, we first evaluated the performance of CCPICPB dye. Upon our optimized experimental condition, the 3% Ca-TiO2 photoanode-based device exhibits an efficiency of 4.04%, which is greater than that of the pristine TiO2 photoanode-based device (2.93%). Because of the quicker electron transport in the Ca-TiO2 film, the short-circuit current density and efficiency of DSSCs were improved. Moreover, when the CCPICPB dye was used as a co-sensitizer with the common Ru(II) dye (Z907), interestingly it showed the highest efficiency (6.11%) when compared with Z907 alone (5.12%). This improved efficiency of the co-sensitized device resulted from greater VOC conjugated with improved JSC. The JSC was improved because CCPICB dye could compensate for the photocurrent loss caused by redox electrolyte while the VOC was improved because electron recombination was inhibited under the co-sensitization conditions.Graphical abstract

Prediction of food additives based on grey prediction model and electrochemical analysis of gallic acid

In this paper, a grey prediction model was used to predict the future consumption of food additives, and then an electrochemical analysis method was combined to focus on the detection of food additives as an example of gallic acid, and to optimize the conditions that may affect the detection results. A series of standard curves describing the concentration of gallic acid (0.0005 μM - 200 μM) were obtained under optimal detection conditions. This study constructs a sensitive, short time-consuming and easy-to-operate assay system for the detection of gallic acid in food additives by electrochemical analysis, and provides a potential method for the quantitative determination of gallic acid in food additives in the future.

A novel method for identifying corrosion types and transitions based on Adaboost and electrochemical noise

PurposeThe purpose of this paper is to identify corrosion types and corrosion transitions by a novel electrochemical noise analysis method based on Adaboost.Design/methodology/approachThe corrosion behavior of Q235 steel was investigated in typical passivation, uniform corrosion and pitting solution by electrochemical noise. Nine feature parameters were extracted from the electrochemical noise data based on statistical analysis and shot noise theory. The feature parameters were analysis by Adaboost to train model and identify corrosion types. The trained Adaboost model was used to identify corrosion type transitions.FindingsAdaboost algorithm can accurately identify the corrosion type, and the accuracy rate is 99.25%. The identification results of Adaboost for the corrosion type are consistent with corroded morphology analysis. Compared with other machine learning, Adaboost can identify corrosion types more accurately. For corrosion type transition, Adaboost can effectively identify the transition from passivation to uniform corrosion and from passivation to pitting corrosion consistent with corroded morphology analysis.Originality/valueAdaboost is a suitable method for prediction of corrosion type and transitions. Adaboost can establish the classification model of metal corrosion, which can more conveniently and accurately explore the corrosion types. Adaboost provides important reference for corrosion prediction and protection.

Understanding of low-carbon steel marine corrosion through simulation in artificial seawater

<abstract> <p>The current laboratory experiments investigated the corrosion resistance of carbon steel in artificial seawater (ASW) using the steel coupons hanging on a closed glass reactor of ASW with volume-to-specimen area ratios ranging from 0.20 to 0.40 mL/mm<sup>2</sup>. These coupons were immersed in ASW for varying time durations (7 and 14 d) at room temperature without agitation. Further, the corrosion rates based on the weight loss and electrochemical analytical method were determined. Following exposure to carbon steel for 7 and 14 d, corrosion rates were 0.2780 <italic>mmpy</italic> and 0.3092 <italic>mmpy</italic>, respectively. The surfaces appeared to be not protected by oxides based on this result. The electrochemical impedance spectrometer in potentiostatic/galvanostatic mode, in conjunction with EDX analysis, predicted the evolution of oxygen reduction. The 7th-day immersion sample had a higher oxygen content, and the 14th-day immersion sample had a slightly lower oxygen content. Methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterized the surface morphology and composition of their corrosion product. Corrosion products derived from rust minerals hematite, lepidocrocite and magnetite appeared to cover the carbon steel surface after exposure. This result can get insight into the corrosion behavior of low-carbon steel used in marine environments.</p> </abstract>

Assay of sodium carbonate

Main textThe CCQM-K173 Assay of Sodium Carbonate key comparison was jointly organized by the Inorganic Analysis (IAWG) and Electrochemical Analysis and Classical Chemical Methods (EAWG) working groups of CCQM to test the abilities of the national metrology institutes (NMIs) to measure the purity or amount content of solid bases. They are important challenges for reference material producers, providers of other measurement services, such as proficiency testing schemes. Evidence of successful participation in formal, relevant international comparisons are needed to support calibration and measurement capability claims (CMCs) made by NMIs and designated institutes (DIs).Nine NMIs participated in this key comparison CCQM-K173. National Institute of Metrology P. R. China (NIM) and Ural Research Institute for Metrology - Affiliated Branch of the D.I. Mendeleyev Institute for Metrology (VNIIM-UNIIM), Russian Federation, acted as the coordinating laboratories of the comparison.The measurement methods used by the participants for measuring the amount content of bases expressed as sodium carbonate were coulometry and titrimetry.In general, good overlap of results was observed, the suitability of coulometry and titrimetry for assay of high purity materials was demonstrated. The majority of results were split in two groups differing from each. This bias was however covered by the stated uncertainty estimates. Various effects have been evaluated that may cause it. However, the reason for the bias has not been identified clearly.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Effects of the corrosion mechanism evolution of low silicon-cast aluminium alloys in service

ABSTRACT The corrosion mechanism evolution of four low silicon-cast aluminium alloys exposed to heat treatment at 200°C for 0–50 h was studied by means of immersion corrosion, intergranular corrosion and electrochemical test, SEM, EDS and EBSD analysis methods. The correlation of corrosion resistance with composition and the thermal exposure time was investigated. The results show that the corrosion mechanism of all aluminium alloys changed after thermal exposure at 200°C. Before thermal exposure, intergranular corrosion was the main corrosion, and after 200°C thermal exposure, serious pitting corrosion and spalling corrosion occurred in the local area. The contents of Si and Mg in the grain boundary increased obviously. The contents of elements in the poor zone of the grain boundary increased, and the electrical potential difference between the grain and the grain boundary reduced. The intergranular corrosion sensitivity of the alloy was reduced. But the degree of pitting gradually becomes serious. The electrochemical test of the aluminium alloy with 3.5 wt% Si showed that its corrosion potential increased with the increase inthermal exposure time, and its corrosion current density increased with the increase inthermal exposure time. After the EBSD test, it was found that the large angle grain boundary decreased gradually and the proportion of large grain size increased with the increase in thermal exposure time to 50 h.

Highly-efficient peroxydisulfate activation by polyaniline-polypyrrole copolymers derived pyrolytic carbon for 2,4-dichlorophenol removal in water: Coupling mechanism of singlet oxygen and electron transfer

Carbonization of N-containing aromatic polymers is a promising route to prepare N-doped carbon materials with low cost, easy regulation, and no external N source. However, there are relatively few studies applying these materials for persulfate activation, and the catalytic mechanisms of the existing reaction systems are divergent. In this paper, a series of N-doped carbon materials were prepared by carbonizing polyaniline (PANI), polypyrrole (PPy), and PANI-PPy copolymers. The copolymer-derived carbon materials exhibit superior peroxydisulfate (PDS) catalytic activity compared to some commercially available and reported carbon materials. Combing quenching experiments, EPR analysis, chemical probe analysis, and various electrochemical analysis methods identified the singlet oxygen (1O2) and electron transfer as the main reaction pathways of all systems, but the contribution of each pathway was influenced by the types of precursors. The structure-activity relationship indicated that the carbonyl group (CO) was the main active site for the 1O2 pathway, while the electron transfer ability of the reaction system and the potential of the complex formed by catalyst and PDS jointly determined the electron transfer pathway. This paper provides a new strategy for obtaining excellent N-doped carbon-based persulfate activators and deepens the insight into the mechanism of PDS activation by N-doped carbon materials.

A hydrogel-based biosensor for stable detection of glucose

Glucose detection is vital in the food industry for safety and quality management. As a healthy ingredient, the flavor of honey is frequently impacted by the crystallization of glucose. Therefore, determining the glucose level can offer precise reference data for the manufacture of honey. Various approaches have been tried, and the enzyme-based electrochemical analytical method is one of the most important and widely used strategies. However, there are still challenges for most electrochemical methods to achieve stable detection resistant to temperature variation due to the easy inactivation of the enzyme, the poor anti-interference capacity of the detection techniques and other influences from the external environment. Herein, a hydrogel-based electrochemical biosensor is proposed to stably detect glucose even at wide ranges of temperatures via electrochemical impedance spectroscopic (EIS) measurement. The key factor for stable detection relies on the metal-organic framework nanoparticles' protective layer to guarantee the robustness of glucose oxidase (GOx), thereby achieving stable and specific detection for glucose. Moreover, a cascade reaction-induced hydrogel formation in a 3D structure can be used as an impedance readout, which not only amplifies but also further stabilizes the GOx-induced response. The prepared hydrogel-based electrochemical biosensor showed a linear response to the glucose concentration in the range of 0.75–4 mg/mL. Furthermore, the biosensor has excellent anti-interference and temperature stability. High performance liquid chromatography analysis also validated the accuracy of this biosensor in detecting glucose in the honey sample.

A Promising Crystalline KCl: Electrolyte Material for Studying the Electrochemical Properties of Cerium on Liquid Indium Electrodes

Potassium chloride crystals are good conductors in the UV to mid-infrared broadband and can be widely used as materials for high-power CO2 lasers. However, the most important use of potassium chloride crystals has been overlooked; their stable chemistry and wide electrochemical window allow them to form molten eutectic salts with other chlorides for the dry reprocessing of spent fuel. The aim of this work is to investigate the electrochemical properties of the actinide substitute cerium metal on liquid indium media in order to provide basic data for further realization of lanthanides (Ln)/actinides (An) separation. In this paper, we investigated the electrochemical behavior of 3LiCl-2KCl-CeCl3 melt at liquid metal media indium (In) electrode using various transient electrochemical analysis methods, such as cyclic voltammetry, square wave voltammetry and open circuit potential technique. The quasi-equilibrium potentials of Ce3+ at different temperatures on the liquid metal In electrode were determined. On the redox process, the reaction kinetics of the oxidation–reduction process in the 3LiCl-2KCl-CeCl3 system is studied. It was determined that the reduction of Ce3+ at the liquid metal In electrode is an irreversible single-step process with three electron transfers. The relationship between the diffusion coefficient and the reduction process of Ce3+ ions on liquid metal indium electrodes at different temperatures was determined. The expression for the diffusion coefficient and temperature of Ce3+ at the liquid metal indium electrode is: lnD = 1.43 − 7974.69/T.

Transition Metal Doped-Chalcogenide Based Electrocatalysts for Oxygen Evolution Reaction

Hydrogen, which possesses high gravimetric energy density, has recently received great attentions to respond to the seriousness of global climate change [1, 2]. In particular, the alkaline water electrolysis cells (AECs) that can produce hydrogen through electrochemical reactions without greenhouse gas emissions are substantially promising as renewable next-generation energy storage and conversion devices. In AECs, oxygen evolution reactions (OERs) occur at the anode, while hydrogen evolution reactions take place at the cathode [3, 4]. However, the sluggish kinetics of the multi-electron transfer process is a paramount challenge for efficient OER activity. Furthermore, precious metal catalysts such as iridium and ruthenium are still mainly used as an OER catalyst, and their low economic efficiency and durability are acting as major problems in the commercialization stage. Therefore, the reduction of reaction overpotential is crucial to boost catalytic efficiency for OER in AECs. In this study, the OER catalyst study is performed on sulfide-based chalcogenide materials. It has been reported that the sulfide-based chalcogenide materials have shown the excellent catalytic activity because the covalent characteristics between transition metal and chalcogenide is stronger than that of oxide-based catalysts [5]. In particular, among various sulfide-based chalcogenide materials, nickel sulfide-based catalysts have actively studied because they can simply synthesize using a hydrothermal method. Additionally, nickel sulfides have a structurally Ni-Ni metal bond that makes it easy to transfer charge species for OERs. Herein, various transition metals are doped into the nickel sulfide to improve the catalytic activity and electrical conductivity via generation of extra defects in the crystal structure. The crystal structure and catalytic activity of chalcogenide catalysts are analyzed through various physicochemical and electrochemical analysis methods.

N/S codoping modification based on the metal organic framework-derived carbon to improve the electrochemical performance of different energy storage devices

Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources, low cost, and environmental friendliness. However, the low capacity and poor high rate performance still constitute great challenges. Metal organic framework-derived carbon has been widely researched because of its high porosity, tunable structure, and good conductivity. In this work, N/S codoped hierarchical porous carbon microspheres were prepared by a high-temperature heat treatment and atomic doping process using a zinc-based organic framework as the precursor. When used as a potassium-ion battery anode, it has a high reversible specific capacity (435.7 mAh g−1), good rate performance (133.5 mAh g−1 at 10,000 mA g−1), and long-term cycling stability (73.2% capacity retention after the 2500th cycle). The potassium storage mechanism of the derived carbon was explained by various electrochemical analysis methods and microstructure characterization techniques, and the relationship between the structural characteristics and electrochemical properties was researched. In a supercapacitor, the porous carbon material exhibits a specific capacitance of 307.2 F g−1 at a current density of 0.2 A g−1 in a KOH aqueous solution and achieves a retention rate of 99.88% after 10,000 cycles. The assembled symmetric supercapacitor device delivers a high energy density of 6.69 Wh kg−1, with a corresponding power density of 2500 W kg−1. In addition, density functional theory calculations further confirmed that N/S codoping can improve the adsorption capacities of potassium and hydroxyl ions in the derived carbon.

Indirect chronovoltametric dosage of alkaline earth metals. The contribution of the chemist Ion Vatamanu to the development of electrochemical methods of analysis

The paper presents the results of a series of investigations on the indirect chronovoltametric dosing of alkaline earth metals, carried out in the Laboratory of the Analytical Chemistry at the Institute of Chemistry, currently called the Laboratory of Physicochemical Methods of Research and Analysis, conducted in 1971–1993 by the doctor of chemical sciences Ion Vatamanu. During the elaboration of the presented polarographic methods for determining the ions of alkaline-earth metals, a series of techniques were used to increase the sensitivity and selectivity of the determination. Based on two indirect polarographic methods for measuring alkaline earth metals, developed by Ion Vatamanu and coworkers and analyzed in this paper, two fundamental physicochemical principles were applied: (I) anion-induced adsorption of ligands adsorbed on the electrode surface and (II) thermodynamic determination of the optimal dosing conditions by calculating the conditional constants or the equilibrium chemical composition of complex reactant systems. The developed methods were used in the electrochemical analysis of standard alloy samples based on various metals, in the analysis of semiconductor systems, ferrous metals, nickel electrolytes, copper plating, cadmium plating, chromium plating, aluminum oxidation, wastewater analysis in galvanic baths, clays and limestones from Moldovan deposits, determination of pesticides, tanning extracts, dyes for the textile industry, etc.

An Efficient Enzyme-Less Uric Acid Sensor Development Based on PbO-Doped NiO Nanocomposites.

Here, the voltammetric electrochemical approach was applied to detect uric acid (UA) in a conductive sensing medium (phosphate buffer solution-PBS) by using PbO-doped NiO nanocomposites (NCs)-decorated glassy carbon electrode (GCE) performing as working electrode. The wet-chemically prepared PbO-doped NiO NCs were subjected to characterization by the implementation of XRD, FESEM, XPS, and EDS analysis. The modified GCE was used to detect uric acid (UA) in an enzyme-free conductive buffer (PBS) of pH = 7.0. As the outcomes of this study reveal, it exhibited good sensitivity of 0.2315 µAµM−1cm−2 and 0.2233 µAµM−1cm−2, corresponding to cyclic (CV) and differential pulse (DPV) voltammetric analysis of UA, respectively. Furthermore, the proposed UA sensor showed a wider detection (0.15~1.35 mM) range in both electrochemical analysis methods (CV & DPV). In addition, the investigated UA sensor displayed appreciable limit of detection (LOD) of 41.0 ± 2.05 µM by CV and 43.0 ± 2.14 µM by DPV. Good reproducibility performance, faster response time and long-time stability in detection of UA were perceived in both electrochemical analysis methods. Finally, successful analysis of the bio-samples was performed using the recovery method, and the results were found to be quite acceptable in terms of accuracy. Thus, the findings indicate a reliable approach for the development of 5th generation biosensors using metal-oxides as sensing substrate to fulfill the requirements of portable use for in situ detection.

Superstructured Nanocrystals/Dual-Doped Mesoporous Carbon Anodes for High-Performance Sodium-Ion Batteries.

Two-dimensional ordered superstructures have been attracting considerable attention due to their interesting properties and potential applications. However, designing ideal functional superstructures with excellent electrochemical properties is still a major challenge, and an in-depth understanding of the structure-activity relationship of electrodes remains to be achieved. To elucidate this critical issue, herein, we rationally designed and synthesized for the first time superstructured TiO2/dual-doped mesoporous carbon anodes using confined space and surface coassembly strategies. Our method primarily relied on the larger interlayer space few-layered MXene and its negatively charged surface, allowing hexamethylenetetramine intercalation and surface electrostatic adsorption. The superstructured TiO2/dual-doped mesoporous carbon was successfully assembled by the thermal decomposition of a confined carbon precursor. Subsequently, the comparison of Na+-storage properties of various anodes was carried out based on the results of structural characterization techniques and electrochemical analysis methods. The results showed that the optimized anode (N/O-C@TiO2-20) can deliver a reversible capacity of 165 mA h g-1 after 1000 cycles at a current density of 1 A g-1, indicating excellent electrochemical properties. The enhancement can be attributed to the synergistic effect of carbon domains, defective nanocrystals, and a covalently coupled interface between TiO2 and mesoporous carbon. Our work not only offered a new strategy for the assembly and regulation of superstructures to promote the electrochemical performance but also enlightened the rational design of advanced anodes for sodium-ion battery application.