Electrochemical Properties Research Articles

From Na to K‐Based Prussian Blue: A Path Toward Cathode Materials for Extreme Environment

AbstractPrussian blue (PB) is regarded as a promising host for Na or K storage because of its sustainable precursor elements (e.g., Mn, Fe) and open framework structure. However, unstable structure, high crystal H2O content, and risky HCN generation restrain its practical applications. In this work, after systematical investigation of structural evolution from Na‐based to K‐based PB and its relationship with electrochemical properties, it is clarified that low crystal water content, high K content, and trace Na doping are essential for a robust structure and stable cycling of PB. It is found that a trace Na‐doped K‐based PB exhibits comprehensive properties of low crystal water content (3.2 wt%), high thermal stability (over 340 °C), and superior cycling stability (84.3% after 6300 cycles at 5 C). Besides, the PB can also present stable cycling under harsh conditions, such as with intermittent‐overcharge/overdischarge steps (4.8 V/1.2 V, 93.3% after 2100 cycles at 5 C), in a wide voltage range (93.2% after 1000 cycles at 1.5‒4.5 V/5 C), under a high rate (83.7% after 4350 cycles at 10 C), and at a high temperature (92.0% after 1650 cycles at 45 °C/1 C). The superior electrochemical properties are attributed to its structural robustness even under harsh conditions.

Side Reaction Turned Positive: Synchronous OER Manipulating the Electrocatalytic Properties of Anodic Electrodeposited Lead Dioxide.

The preparation and modification of porous electrodes are an important component of the new generation electrochemical oxidation technology. Rapid preparation of porous electrodes can be easily achieved by synchronous oxygen bubble electrodeposition. However, according to the reaction mechanism of lead dioxide anodic electrodeposition, there is bound to be a competitive reaction of adsorbed hydroxyl radicals in the oxygen bubble template method, which means that synchronous OER impacts both the surface morphology andpotentiallythe crystalline structure of the metal oxides. Clarifying the comprehensive influence of synchronous OER on the morphology and microstructure of the coating is important. In this work, the electrodeposition process of porous lead dioxide coating is regulated by the way of linear potential increase and realized the rapid preparation of high-performance porous lead dioxide coating within 40 s. The morphology and microstructure, electrical, and electrochemical properties are characterized, combined with theoretical calculation and orthogonal analysis, to investigate the regulatory mechanism of the rapid growth of the porous lead dioxide by the electric potential. It is demonstrated that synchronous OER confers porous morphology and a large number of defects to the coating in situ, and enhancing the electrocatalytic oxidation performance of the electrode.

Ternary NASICON-Type Na3.25VMn0.25Fe0.75(PO4)3/NC@CNTs Cathode with Reversible Multielectron Reaction and Long Life for Na-Ion Batteries.

Na superionic conductor (NASICON)-structure Na4MnV(PO4)3 (NVMP) electrode materials reveal highly attractive application prospects due to ultrahigh energy density originating from two-electron reactions. Nevertheless, NVMP also encounters challenges with its poor electronic conductivity, Mn dissolution, and Jahn-Teller distortion. To address this issue, utilizing N-doped carbon layers and carbon nanotubes (CNTs) for dual encapsulation enhances the material's electronic conductivity, creating an effective electron transport network that promotes the rapid diffusion and storage of Na+. On this basis, partially substituting Mn in NVMP with Fe, a new sodium superionic conductor (NASICON) structured cathode material has been designed to alleviate Jahn-Teller distortion and prolong the cycling life. The synergistic effect of N-doped double nanocarbon encapsulation and multielectron reactions is employed to promote the optimized Na3.25VMn0.25Fe0.75(PO4)3/NC@CNTs (NVMn0.25Fe0.75P/NC@CNTs) electrode material to deliver fast Na+ diffusion kinetics, high reversible capacity (110.2 mAh g-1 at 0.1 C), and long-term cyclic stability (80.1% of the capacity at 10 C over 2000 cycles). Besides, the electrochemical properties of NVMn0.25Fe0.75P/NC@CNTs composites were investigated in detail at high loads and high window voltages to evaluate their potential for practical applications. The reduction/oxidation processes involved in Fe2+/Fe3+, Mn2+/Mn3+, and V3+/V4+ redox couples and a solid-solution and biphasic reaction mechanism upon repeated de- and re-intercalation processes are revealed via ex-situ XRD and XPS characterization. Finally, the assembled NVMn0.25Fe0.75P/NC@CNTs ∥ hard carbon full cell manifests high capacity (101.1 mAh g-1 at 0.1 C) and good cycling stability (98.2% capacity retention at 1 C after 100 cycles). The rational design with multimetal ion substitution regulation has the potential to open up new possibilities for high-performance sodium-ion batteries.

Luminescent Mesoporous Squaraine Copolymers: Probing the Structural, Optical, and Sensing Behaviors

ABSTRACTHerein, we have designed and developed four luminescent mesoporous squaraine copolymers (PSQ‐X) based on substituted diaryl‐1,4‐diamine moiety with various heteroatom “X” such as CH2, O, S, and SO2 to demonstrate the effect of heteroatom on structural, thermal, electrochemical, and optical properties of copolymers. Synthesis has been achieved through a facile single step metal‐free poly‐condensation reaction using commercially available low‐cost monomers. All polysquaraines (PSQs) possess good thermal stability, crystallinity and low bandgap energy (2–3 eV). Utilizing the fluorescent nature of the PSQs, we have explored them as a “turn‐off” sensor for the selective and sensitive detection of picric acid among various nitro‐aromatic explosives via photoinduced electron transfer (PET) and inner filter effect (IFE) mechanism. The Stern–Volmer constant (KSV) for PA has estimated as 1.93 × 104, 1.92 × 104, 0.68 × 104, and 3.57 × 104 M−1 for PSQ‐CH2, PSQ‐O, PSQ‐S, and PSQ‐SO2, respectively, indicating that PA can quench the emission intensity of PSQ‐SO2 most efficiently with the detection limit in the nano‐molar range (LOD = 5.96 nM). Contact mode detection of PA has been also accomplished using economical and transportable fluorescent paper test strip devices for on‐site sensing, which can detect a minimum of 6.9 fg of PA.

A safe and robust in-situ polymerized cementitious electrolyte coupled with NiCo2S4@CuCo2S4 electrode for superior load-bearing integrated electrochemical capacitor.

Load bearing/energy storage integrated devices (LEIDs) featuring cementitious electrolytes have become ideal for large-scale energy storage. Nevertheless, the progression of LEIDs is still in its nascent phase and considerable endeavors concerning cementitious electrolytes and electrode materials are necessary to further boost the charge storage ability. Here, we propose a facile synchronous reaction method for preparing sodium acrylate (SA)-based in-situ polymerized cementitious electrolyte. The soft polymer network and hard cement matrix are interwoven together. The resulting cementitious electrolyte not only exhibits improved mechanical properties (flexural strength of 14.7MPa and compressive strength of 44.7MPa), but also possesses enhanced ionic conductivity (26.7mScm-1). Moreover, a core-shell NiCo2S4@CuCo2S4/NF heterostructure is synthesized on nickel foam (NF) substrate by hydrothermal assisted electrodeposition techniques, which showcases a remarkable capacitance of 5626.6mFcm-2 at 1mAcm-2. As a proof, with integrated merits of the optimal cementitious electrolyte and NiCo2S4@CuCo2S4/NF electrode, the as-built LEID demonstrates a high energy density of 138.5μWhcm-2 at 0.75mWcm-2 and a cycling durability of 90.7% after 8000 cycles, showing good practicability in lighting light-emitting diodes (LEDs) or driving a thermal hygrometer. Notably, the LEID can endure external forces without distinctly sacrificing electrochemical properties. This work provides insight into developing novel cementitious electrolytes and electrode materials toward superior LEIDs.

Corrosion of Low-Alloy Steel in Ethanolamine Steam Generator Chemistry-The Effect of Temperature and Flow Rate.

The corrosion of low-alloy steel in ethanolamine solution, simulating steam generator chemistry, is studied by in situ chronopotentiometry and electrochemical impedance spectroscopy combined with ex situ analysis of the obtained oxide films and model calculations. Hydrodynamic calculations of the proposed setup to study flow-assisted corrosion demonstrate that turbulent conditions are achieved. Quantum chemical calculations indicate the adsorption orientation of ethanolamine on the oxide surface. Interpretation of impedance spectra with a kinetic approach based on the mixed-conduction model enabled estimating the rate constants of oxidation at the alloy-oxide interface, as well as charge transfer and ionic transport resistances of the corrosion process. In turbulent conditions, the dissolution of Fe oxide and ejection of Fe cations are enhanced, leading to Cr enrichment in the oxide and alteration of its electronic and electrochemical properties that influence the corrosion rate.

Synthesis and structural studies of ruthenium(II) and rhodium(IV) complexes bearing tridentate sulfoxide Schiff base ligands

One new sulfoxide-containing Schiff base, (E)-4-chloro-2-((2-(methylsulfinyl phenyl)imino)methyl) phenol (HL) was coordinated with ruthenium and rhodium, affording five ruthenium(II) complexes [RuCl(L)(CO)2] (1), [RuCl(L)(dmso)2] (dmso = dimethylsulfoxide, 2), [RuCl(L)(PPh3)(CH3CN)] (3), [RuCl(L)(CO)(PPh3)] (4), [RuCl(NOS-LH2)(CO)(PPh3)] (5) and one rhodium(IV) complex [RhCl3(L)] (6). Molecular structures of HL and complexes 1–6 were established by single crystal X-ray diffraction analysis. Moreover, the free ligand HL and its complexes 1–6 were characterized by infrared, NMR, UV-vis, and fluorescence spectroscopies, and their electrochemical properties were also investigated. The ruthenium complexes showed good catalytic activity for the cyclopropylation of styrene.

Structural Regulation and Performance Enhancement of Carbon-Based Supercapacitors: Insights into Electrode Material Engineering.

The development of carbon-based supercapacitors is pivotal for advancing high energy and power density applications. This review provides a comprehensive analysis of structural regulation and performance enhancement strategies in carbon-based supercapacitors, focusing on electrode material engineering. Key areas explored include pore structure optimization, heteroatom doping, intrinsic defect engineering, and surface/interface modifications. These strategies significantly enhance electrochemical performance through increasing surface area, improving conductivity, facilitating charge transfer, introducing additional pseudocapacitive reactions, and optimizing the density of states at the Fermi level, among other mechanisms. After introducing these fundamental concepts, the review details various preparation methods and their effects on supercapacitor performance, highlighting the interplay between material structure and electrochemical properties. Challenges in scaling advanced fabrication techniques and ensuring the long-term stability of functionalized materials are discussed. Additionally, future research directions are proposed, emphasizing the development of cost-effective, scalable methods and interdisciplinary approaches to design next-generation supercapacitors, thereby meeting the growing demand for efficient and sustainable energy storage solutions.

Carbazolylpyridine (cp)-based tetradentate platinum(II) complexes containing fused 6/5/6 metallocycles.

A series of carbazolylpyridine (cp)-based 6/5/6 Pt(II) complexes featuring tetradentate ligands with nitrogen or oxygen atoms as bridging groups was designed and synthesized, and the bridging nitrogen atoms were derived from acridinyl (Ac), azaaceridine (AAc) and carbazole (Cz). Systematic experimental and theoretical studies reveal that the ligand structures have a significant effect on the electrochemical, photophysical and excited state properties of these complexes. Their oxidation processes mainly occur on the carbazole-Pt moieties, whereas the reduction processes typically occur on the electron-deficient pyridine (Py) moieties. Time-dependent density functional theory (TD-DFT) and natural transition orbital (NTO) calculations reveal that the cp-based Pt(II) complexes have a metal-to-ligand charge transfer (3MLCT) state mixed with ligand-centered (3LC) and intra-ligand charge-transfer (3ILCT) characteristics. Pt(cp-1) shows strong red luminescence with a dominant peak at 611 nm and an excited-state lifetime of 10.7 μs in dichloromethane at room temperature, 602 nm and 10.9 μs in toluene, and 602 nm and 8.2 μs in PMMA films. It also exhibits high photoluminescence quantum efficiencies of 85%, 84% and 60% in dichloromethane, toluene and PMMA, respectively. These studies indicate the potential application of the cp-based Pt(II) complexes as phosphorescent emitters in the field of organic light-emitting diodes (OLEDs).

Phosphorus-nitrogen compounds. Part 77. The synthesis of novel ferrocenyl(N/O)spiro- and 2-cis-4-dichloro-ferrocenyl(N/O)ansa-cyclotetraphosphazenes with 9-ethyl-3-carbazolyl pendant arm(s): spectral, bioactivity, electrochemical and dye-sensitized solar cell fabrication studies

Herein, the reactions of octachlorocyclotetraphosphazene (OCCP, 1) with sodium-3-ferrocenylmethyl-amino)-1-propanoxide (L1) gave hexachloro-ferrocenyl-(N/O)-spiro-2 and 2-cis-4-dichloro-ferrocenyl-(N/O)-ansa-3 cyclotetraphosphazenes in THF. Spiro- (2) reacted with excess 9-ethyl-N-methyl-3-carbazolyl-1,3-diaminopropane (L2) and 9-ethyl-N-ethyl-3-carbazolyl-1,2-diaminoethane (L3) to produce 2-trans-6-dispiro ( dispiro-2a) and 2-trans-4-cis-6-trans-8-tetraspiro ( tetraspiro-2b) cyclotetraphosphazenes, respectively. The reactions of ansa-3 with excess L2 led to the formation of monospiro {2-cis-4-dichloro-ansa-2-trans-6-spiro(N/N) ( ansa-spiro-3b)} and dispiro {2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/N) ( ansa-dispiro-3b)} cyclotetraphosphazenes. However, the reactions of ansa-3 with excess 9-methyl-N-ethyl-3-carbazolyl-1,2-diaminomethane (L4) afforded 2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/N) ( ansa-dispiro-3a). Ansa-3 was also reacted with excess sodium 3-(9-ethyl-carbazolamino)-1-propanoxide (L5) to give 2-cis-4-dichloro-ansa-2-trans-6-spiro(N/O) ( ansa-spiro-3c) and 2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/O) ( ansa-dispiro-3c) cyclotetraphosphazenes. Reactions were carried out by classical and microwave-assisted methods. These novel multi-heterocyclic inorganic/organic hybrid cyclotetraphosphazenes can offer valuable insights into developing new materials. Tetraspiro-2b and all ansa compounds have more than one stereogenic P-atom. The optical and electrochemical properties of some cyclotetraphosphazenes were investigated using UV-vis absorption and cyclic voltammetry (CV) techniques. As a result, these phosphazenes can be suggested as ferrocene-based charge transformable structures. They can be used as new-generation and synergistic dye-sensitized solar cell (DSSC) materials. Additionally, antimicrobial activities of five compounds ( dispiro-2a, ansa-spiro-3b, ansa-dispiro-3b, ansa-spiro-3c and ansa-dispiro-3c) against various pathogenic bacteria and yeasts were evaluated. Their interactions with pBR322 plasmid DNA were also investigated.

Surface treatment improving the mechanism and electrochemical properties of lead anodes by sandblasting

Surface treatment improving the mechanism and electrochemical properties of lead anodes by sandblasting

Doping Engineering of Sodium Vanadium Fluorophosphates Cathodes for Sodium-Ion Batteries

Abstract Sodium-ion batteries offer a promising alternative to lithium-ion batteries due to the abundance and low cost of sodium resources. Na3V2(PO4)2F3−y O y (NVPFO y ) stands out as a cathode material with high average operating potential (~ 3.9 V vs Na+/Na), fast Na⁺ transport, and strong structural stability (minimal volumetric strain of ~ 2%). This review addresses the structural characteristics and charge storage mechanisms of NVPFO y , focusing on charge compensation and Na⁺/vacancy ordering. It also discusses recent advances in lattice regulation and doping strategies to enhance electrochemical properties. Finally, we highlight challenges and future directions for practical applications, emphasizing the correlation between crystal structure and performance.

Insights into Homogeneous Bulk Boron Doping at the Tetrahedral Site of NCM811 Cathode Materials: Structure Stabilization by Inductive Effect on TM-O-B Bonds.

Rechargeable lithium-ion batteries (LIBs) are critical for enabling sustainable energy storage. The capacity of cathode materials is a major limiting factor in the LIB performance, and doping has emerged as an effective strategy for enhancing the electrochemical properties of nickel-rich layered oxides such as NCM811. In this study, boron is homogeneously incorporated into the tetrahedral site of NCM811 through co-precipitation, leading to an inductive effect on transition metal (TM)-O-B bonds that delayed structural collapse and reduced oxygen release. Consequently, these changes culminate in an enhancement of cycling performance, translating to an initial specific capacity of 210mAh g-1 and a 95.3% capacity retention after 100 cycles. These interesting findings deepen the understanding of boron doping and shed light on the design of better lithium cathode materials on an applicable scale.

Synthesis of Graphene Nanosheets from Coconut and Candlenut Shells: Large-Scale Production and Application in Fe Ion Adsorption and Electrochemical Properties

Synthesis of Graphene Nanosheets from Coconut and Candlenut Shells: Large-Scale Production and Application in Fe Ion Adsorption and Electrochemical Properties

Effect of growth dynamics on the structural, photophysical and pseudocapacitance properties of famatinite copper antimony sulphide colloidal nanostructures (including nanosheets).

Facile phase selective synthesis of copper antimony sulphide (CAS) nanostructures is important because of their tunable photoconductive and electrochemical properties. In this study, off-stoichiometric famatinite phase CAS (fCAS) quasi-spherical and quasi-hexagonal colloidal nanostructures (including nanosheets) of sizes, 2.4-18.0 nm were grown under variable conditions of temperature (60-200 °C), time and oleylamine capping ligand concentration using copper(II) acetylacetonate and antimony(III) diethyldithiocarbamate precursors. Data from powder X-ray diffraction, Raman spectroscopy and high-resolution scanning/transmission electron microscopy confirm the tetragonal structure of the famatinite phase. X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy data suggest a correlation of particle size, morphology and composition of the off-stoichiometric fCAS nanostructures with growth temperature and time, and oleylamine concentration. The off-stoichiometric Cu3-aSb1+bS4±c (a, b, c - mole fractions) nanostructures being severely copper-deficient and antimony-rich, exhibit shallow-lying acceptor copper vacancy states, deep-lying donor states of antimony interstitials, sulphur vacancies and antimony-copper antisites and shallow-lying acceptor surface trapping states. These electronic states are likely implicated in tunable UV-visible absorption and bandgaps between 2.3 and 2.8 eV, and broad visible-NIR photoluminescence with fast recombination of radiative lifetimes between 0.2 and 6.2 ns, confirmed from absorption, steady-state and time-resolved photoluminescence spectroscopies. Additionally, cyclic voltammetry and electrochemical impedance spectroscopy confirm that electrodes of the fCAS nanostructures display slightly variable pseudocapacitance of charge-storage primarily via possible sodium ion intercalation with a high specific capacitance of ∼84 F g-1 obtained at a scan rate of 5 mV s-1. Overall, these results show the influence of composition, in particular point defects, phase quality and morphology on the optical and pseudocapacitance properties of fCAS nanostructures, suitable as solar absorbers or electrodes for energy storage devices.

Breaking Anionic Solvation Barrier for Safe and Durable Potassium-ion Batteries Under Ultrahigh-Voltage Operation.

Ultrahigh-voltage potassium-ion batteries (PIBs) with cost competitiveness represent a viable route towards high energy battery systems. Nevertheless, rapid capacity decay with poor Coulombic efficiencies remains intractable, mainly attributed to interfacial instability from aggressive potassium metal anodes and cathodes. Additionally, high reactivity of K metal and flammable electrolytes pose severe safety hazards. Herein, a weakly solvating fluorinated electrolyte with intrinsically nonflammable feature is successfully developed to enable an ultrahigh-voltage (up to 5.5 V) operation. Through breaking the anionic solvation barrier, synergistic interfacial modulation can be achieved by the formation of robust anion-derived inorganic-rich electrode-electrolyte interfaces on both the cathode and anode. As proof of concept, a representative KVPO4F cathode can sustain 1600 cycles with 84.4% of capacity retention at a high cutoff voltage of 4.95 V. Meanwhile, K plating/stripping process in our designed electrolyte also demonstrates optimized electrochemical reversibility and stability with effectively inhibited potassium dendrites. These findings underscore the critical impact of anion-dominated solvation configuration on synergistic interfacial modulation and electrochemical properties. This work provides new insights into rational design of ultrahigh-voltage and safe electrolyte for advanced PIBs.

A comparative study on the structural, chemical, morphological and electrochemical properties of α-MnO2, β-MnO2 and δ-MnO2 as cathode materials in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered to be highly promising electrochemical energy storage device due to their affordability, inherent safety, large zinc resources, and optimal specific capacity. Among various cathode materials, manganese dioxide (MnO2) stands out for its high voltage, environmental benignity, and theoretical specific capacity. This study systematically investigates the phase formation and structural parameters of α-MnO2, β-MnO2, and δ-MnO2 synthesized via hydrothermal method, employing Rietveld refinement. FTIR and Raman spectroscopy confirms Mn-O and O-H bond formation. BET analysis reveals surface areas, and pore size distribution is calculated with BJH method. High-resolution XPS spectra exhibit a spin energy split of ~ 11.9 eV for Mn 2p confirming the presence of MnO2. Electrochemical studies shows an initial discharge capacities of 230.5, 188.74 and 263.30 mAh g− 1 at 0.1 A g− 1 for α-MnO2, β-MnO2 and δ-MnO2. The EIS spectra revealed the capacitive behaviour and electrode reaction kinetics where a RcT value of 484.14, 327.6, 162.5 Ω for α-MnO2, β-MnO2 and δ-MnO2. These study give insights into relation of various properties of MnO2 with electrochemical performance and its viability in grid storage applications.Graphical

Structure and Morphological Properties of Cobalt-Oxide-Based (Co3O4) Materials as Electrodes for Supercapacitors: A Brief Review.

Over the past 15 years, there has been a significant increase in the search for environmentally friendly energy sources, and transition-metal-based energy storage devices are leading the way in these new technologies. Supercapacitors are attractive in this regard due to their superior energy storage capabilities. Electrode materials, which are crucial components of supercapacitors, such as cobalt-oxide-based electrodes, have great qualities for achieving high supercapacitor performance. This brief review presents some basic concepts and recent findings on cobalt-based materials used to fabricate electrodes for supercapacitors. The text also clarifies how morphological characteristics typically influence certain properties. The inner surface of the electrode exhibits several properties that change to provide it a great boost in specific capacitance and charge storage. Porous structures with defined pore sizes and shapes and high surface areas are important features for improving electrochemical properties. Finally, we present some perspectives for the development of cobalt-oxide-based supercapacitors, focusing on their structure and properties.

Electrochemical Properties of ZrNi1.2 Mn0.5Cr0.2V0.1 and ZrNi1.2 Mn0.45Cr0.2V0.15 Alloy Electrodes Depending on Discharge Modes

Electrochemical Properties of ZrNi1.2 Mn0.5Cr0.2V0.1 and ZrNi1.2 Mn0.45Cr0.2V0.15 Alloy Electrodes Depending on Discharge Modes

Study on the Radiation Synthesis Mechanism and the Electrochemical Property of Polyaniline

Study on the Radiation Synthesis Mechanism and the Electrochemical Property of Polyaniline