Abstract: Sodium-ion batteries (SIBs) have emerged as a viable alternative to lithium-ion technologies, with carbon-based anodes playing a pivotal role in addressing key challenges of sodium storage. This review systematically examines hard carbon as the premier anode material, elucidating its dual sodium storage mechanisms: 1) sloping capacity (2.0-0.1 V vs Na+/Na) from surface/defect adsorption and 2) plateau capacity (<0.1 V) via closed-pore filling and pseudo-graphitic intercalation. Through critical analysis of recent advancements, we establish that optimized hard carbon architectures delivering 300-400 mAh/g capacity require precise coordination of pseudo-graphitic domains (d002 = 0.36-0.40 nm) and sub-1 nm closed pores. This review ultimately provides a design blueprint for next-generation carbon anodes, proposing three research frontiers: 1) machine learning-guided microstructure optimization, 2) dynamic sodiation/desodiation control in sub-nm pores, and 3) scalable manufacturing of heteroatom-doped architectures with engineered pseudo-graphitic domains. These advancements position hard carbon anodes as critical enablers for high-performance, cost-effective SIBs in grid-scale energy storage applications.

Abstract: Supercapacitors (SCs) have attracted much attention due to their high-power density and long cycle life, where carbon materials have become the focus of electrode material research due to their excellent conductivity, stability, and reproducibility. However, the low specific capacitance and specific surface area of carbon materials lead to poor electrochemical properties, which seriously hinder their practical applications. The work here presents a simple but effective strategy to construct hollow nanocage structures by tannic acid etching ZIF-8. In this process, tannic acid releases protons to etch the MOF structure, and the remaining relatively large molecules are attached to the surface of ZIF-8 to prevent its structure from collapsing, and after high-temperature heat treatment, novel hollow nitrogen-doped carbon nanocage structures (HNCs) are obtained. Electrochemical tests show that the material has a capacity of 349.3 F g-1 at a current density of 0.5 A g-1, and still has a coulombic efficiency of 97.61% as well as a capacity retention of 97.86% after cycling for 10, 000 cycles at a current density of 3 A g-1. Therefore, this study provides a novel idea to explore the application of carbon materials with excellent electrochemical performance for energy storage.

Abstract: This study explores the development of aluminum doped MgV2O4 spinel cathodes for aqueous zinc-ion batteries (AZIBs), aiming to overcome the challenges of poor ion diffusion and structural instability. Al3+ ions were pre-inserted into the spinel structure using a sol-gel method, enhancing the material's structural stability and electrical conductivity. The Al3+ doping mitigates the electrostatic interactions between Zn2+ ions and the cathode, improving ion diffusion and facilitating efficient charge/discharge processes. The resulting Al-MgV2O4 cathode demonstrates excellent electrochemical performance, retaining a capacity of 254.3 mAh g−1 at an ultra-high current density of 10 A g−1 after 1000 cycles, with a capacity retention of 93.6%. At an ultra-high current density of 20 A g−1, the material retains 186.8 mAh g−1 after 2000 cycles, with a capacity retention of 90.2%, making it a promising candidate for high-rate energy storage applications.

Abstract: Ru-based catalysts manifest unparalleled hydrogen evolution reaction (HER) performance, but the hydrolysis of Ru species and the accumulation of corresponding reaction intermediates greatly limit HER activity and stability. Herein, Mo single atoms modified Ru nanoparticles assemblies supported on N-incorporated graphene (referred to as MoRu-NG) are compounded via hydrothermal and chemical vapor deposition methods (CVD). The incorporation of Mo single atoms into Ru lattices modifies the local atomic milieu around Ru centers, significantly improving HER catalytic behavior and stability. More specifically, MoRu-NG achieves the overpotential of 53 mV and 28 mV at 10 mA cm–2 with exceptional stability in acidic and alkaline seawater solutions, respectively. In MoRu-NG, Ru atoms have special electronic structure and thus possess optimal hydrogen adsorption energy, which indicates that the excellent HER activity mainly hinges upon Ru centers. To be specific, the d-electron orbitals of Ru atoms are close to half full, giving Ru atoms moderate bond energy for the assimilation and release of hydrogen, which is beneficial for the conversion of reaction intermediates. Moreover, the incorporation of Mo single atoms facilitates the formation of O, O'-bidentate ligands, significantly enhancing the structural stability of MoRu-NG in pH-universal seawater electrolysis. This work advances a feasible construction method of hexagonal octahedral configuration (Ru–O–Mo–N–C) and provides a route to synthesize the efficient and stable catalyst for electrocatalytic HER in pH-universal seawater.

Abstract: The research work presented here describes the development of catalytic surfaces immobilizing dopamine via cross-linking or tyrosinase via covalent bond on an electrografted screen-printed carbon electrode with a 4-nitrobenzenediazonium ion. A simple electrochemical reduction approach was used to graft aryldiazonium ions onto commercial electrodes, resulting in the formation of a covalently bonded aromatic layer on the electrode surface. After functionalization with aminophenyl groups, dopamine, an important neurotransmitter, was immobilized by imine bond formation using glutaraldehyde as a bifunctional cross-linking molecule. The presence of immobilized dopamine was confirmed by cyclic voltammetry following the electrochemical response of the hydroquinone/quinone redox process from catechol functionalities on the surface, which are responsible for the catalytic activity. In addition, the surface was also characterized by cyclic voltammetry using the redox probe, [Fe(CN)6]3-/4-, obtaining a signal on this catalytic DA-biosensor about 14 times higher than that of a bare electrode, achieving a dynamic concentration range spanning three orders of magnitude. Remarkable sensitivity was also obtained by combining the electrografting, in situ diazotation to generate grafted aryl diazonium ions on the surface and coupling reaction to anchor the tyrosinase enzyme to the electrode surface. The response of the TYR-biosensor towards catechol, using the redox probe as mediator, was 10 times higher than that obtained with the dopamine modified catalytic surface. These modified surfaces offer promising alternatives for the voltammetric quantification of catechol in environmental fields.

Abstract: The properties of Naf-TMS (Nafion-trimethylsilyl) and Naf-TMS/Ru-complex modified electrodes are reported for the electrochemical oxidation reaction of adrenaline (AD). The structure of Naf-TMS allows for hydrophobic and hydrophilic interactions with [Ru(bpy)3]2+ and [Ru(phen)3]2+ complexes in order to form stable Naf-TMS/Ru-complex polymer composites. Electrodes modified with this composite polymer, showed a faster electron transfer and greatly improved kinetic values for the redox reaction of AD in standard solutions, when compared to bare and Naf-TMS modified electrodes. A pH dependence of the electroanalytical parameters indicates that electron transfer reaction occurs in tandem with proton transfer, this allows to find the best analytical conditions for the detection of AD with Naf-TMS/Ru-complex modified electrodes.

Abstract: The galvanostatic intermittent titration technique (GITT) was applied to NMC622 positive electrodes, with Electrochemical Impedance Spectroscopy (EIS) performed at quasi-equilibrium conditions determined by cutoff criteria based on relaxation rates. Below an open-circuit voltage (OCV) of 3.8 V, the cutoff criterion of 0.1 mV h−1 was reached after approximately 8 hours. However, above 3.8 V, a non-saturating voltage decay was observed, increasing up to ∼0.56 mV h−1 above 4.1 V during charging steps. This persistent voltage decay upon subsequent discharging steps led to non-monotonic relaxation behavior. A pulse time of 10 minutes did not satisfy the t dependence required for GITT kinetic analysis. Instead, the initial 36-second transients were extended for chemical diffusivity evaluation, aligning with the Warburg-like response observed in EIS, consistent with the sequential reaction-diffusion assumption. GITT analysis for solid-state diffusivity is ineffective for spherical active particles dispersed in porous electrodes and performs even worse due to liquid-phase diffusion within the pores, where t+=0.3. The apparent SOC-independent chemical diffusivity obtained from GITT across both low and high OCV ranges suggests that the process is dominated by liquid-phase diffusion. The application of the physics-based three-rail transmission line model (TLM) developed by Gaberšček et al. in EIS holds practical potential for deconvoluting the two diffusion kinetics.

Abstract:

While renewable energy sources supply a progressively larger share of the world’s energetical needs, their non-continuous nature demands coupling with energy storage systems such as batteries or capacitors. Consequently, copper oxide-based materials have emerged as promising candidates due to their affordability, stability, and suitable electrochemical performance. In this study, nanostructured copper oxide-based films were electrochemically synthesized on copper foil and foam electrodes and investigated for their supercapacitive behaviour. The synthesis was carried out via cyclic voltammetry (CV) for up to 1000 cycles in an alkaline electrolyte. By tuning the upper vertex potential (-0.3 V to 0.65 V vs Ag/AgCl), both phase composition (Cu₂O, Cu(OH)₂, CuO) and morphology (grains, nanoneedles, nanoplatelets) were precisely controlled, demonstrating the versatility of this approach. EIS data using foil and foam electrodes shows that various processes occur on the electrode during changing potential from -1,0 to 0,6 V and back. The capacitive properties of the synthesized films were evaluated using CV in the potential range of 0 V–0.65 V, and the optimized CuO film synthesized on Cu foam exhibited a high specific capacitance of 2760 mF cm⁻². Charge-discharge cycling at 100 mV s⁻¹ for 1000 cycles indicated an initial capacitance increase followed by stable retention, highlighting the structural integrity and electrochemical stability of the films. These findings provide valuable insights into the controlled electrochemical synthesis of copper oxide nanostructures and their potential for high-performance capacitor applications.

Abstract: A sustainable reaction of electrocatalytic nitrate conversion in ammonia production (NO3RR) occurring under ambient conditions is currently of prime interest, as well as urgent research due to the real potential replacement of the environmentally unfavorable Haber-Bosch process. Herein, a series of electrocatalysts based on two-component cobalt alloys was synthesized using low-cost non-noble metals Co, Fe, Cr and also Si. The samples of electrocatalysts were characterized and studied by the following methods: SEM, EDX, XRD (both transmission and reflection), UV-vis spectroscopy, optical microscopy, linear (and cyclic) voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Beyond that, the determination of electrochemically active surface area was also carried out for all samples of electrocatalysts. Unexpectedly, the sample having an intermetallic compound (IMC) of the composition Co2Si turned out to be the most highly effective. The highest Faradaic efficiency (FE) of 80.8% at E = -0.585 V (RHE) and an ammonia yield rate of 22.3 µmol h-1 cm 2 at E = 0.685 V (RHE) indicate the progressive role of IMC as the main active component of the electrocatalyst. Thus, this study demonstrates the promise and enormous potential of IMC as the main component of highly efficient electrocatalysts for NO3RR. This work can serve primarily as a starting point for future studies of electrocatalytic conversion reactions in the production of ammonia using IMC catalysts containing non-noble metals.

Abstract: Composite electrolytes for applications in electrochemical energy technology, i.e. in batteries and supercapacitors, are gaining increasing attention. In the absence of a commonly accepted definition a ternary combination of materials, e.g. a polymer with an electrolyte salt or electrolyte salt solution and a third conductivity-enhancing constituent, is assumed as a definition of a composite electrolyte in the following review. Relevant fundamentals and reported research results up to explanations of the observed effects and improvements are reviewed. Future perspectives and directions of further research are indicated.

Abstract:

Silver-white, matte, smooth, and durable deposits of silver-rhenium, with thicknesses ranging from 2.0 to 13.7 μm and containing 0.15 to 13.5 wt.% Re, were obtained with a current efficiency of 66-98% from a developed dicyanoargentate-perrhenate bath based on a borate-phosphate-carbonate silver-plating electrolyte. The study was focused on the influence of bath composition, the [Ag(I)]:[ReO₄^-] ratio, surfactant additives, applied current density, temperature, and stirring, on the alloys composition, structure, morphology, microhardness, adhesion, and porosity. A voltammetric analysis was conducted, considering the influence of ethanolamines on electrode processes. In baths with TEA, coatings similar to a silver matrix with rhenium doped in mass fractions are likely achievable. MEA is recommended due to its process-activating properties. All coatings were nanocrystalline (τ = 28.5 - 35 nm). For deposits containing less than 10 wt.% Re, characteristic silver XRD peaks were observed, while other deposits, additional peaks attributed probably to Re(VII) and Re(VI) oxides. A linear relationship, typical for Hall-Petch plots, was obtained, confirming that grain boundaries play a crucial role in mechanical properties of coatings. The conditions for stable electrochemical synthesis of promising functional Ag-Re coatings of predetermined composition (0.7-1.5 wt.% Re) were proposed for practical use in power electronics and energy sectors, for manufacturing electrical contacts operating across a wide temperature range. This was realized by deposition from an Ag-rich bath in the area of mixed electrochemical kinetics, at potential values corresponding to the region of half the limiting current: j = 2.5 ‒ 6 mA cm^-2, t = 19 - 33°C.

Abstract: The electrochemical reduction of nitrate (NO3RR) to ammonia (NH3) provides a decentralized and environmentally friendly route for sustainable ammonia production while addressing the urgent issue of nitrate pollution in water bodies. Recent advancements in NO3RR research have improved catalyst design, mechanistic understanding, and electrolyzer technology, enhancing selectivity, yield, and energy efficiency. This review explores cutting-edge developments, focusing innovative designs of catalyst and electrolyzer such as membrane electrode assemblies (MEA) and electrolyzer configuration, understanding the role of membranes in MEA designs, and various types of hybrid reactors, and membrane-free reactors. Furthermore, the integration of NO3RR with anodic oxidation reactions has been demonstrated to improve overall efficiency by generating valuable co-products. However, challenges such as competitive hydrogen evolution, catalyst degradation, and scalability remain critical barriers to large-scale adoption. We provide a comprehensive overview of recent progress, evaluates current limitations, and identifies future research directions for realizing the full potential of NO3RR in sustainable nitrogen cycling and ammonia synthesis.

Abstract: The application of deep eutectic solvents (DESs) as an innovative class of ionic liquids represents a significant advancement in materials science, especially for the development and enhancement of structural materials. Among the promising applications, DESs are particularly attractive for the electrodeposition of corrosion-resistant coatings. It is established that corrosion-resistant and protective coatings, including those based on metals, alloys, and composite materials, can be synthesized using both traditional aqueous electrolytes and non-aqueous systems, such as organic solvents and ionic liquids. The integration of DESs in electroplating introduces a unique capacity for precise control over microstructure, chemical composition, and morphology, thereby improving the electrochemical corrosion resistance and protective performance of coatings. This review focuses on the electrodeposition of corrosion-resistant and protective coatings from DES-based electrolytes, emphasizing their environmental, technological, and economic benefits relative to traditional aqueous and organic solvent systems. Detailed descriptions are provided for the electrodeposition processes of coatings based on zinc, nickel, and chromium from DES-based baths. The corrosion-electrochemical behavior and protective characteristics of the resulting coatings are thoroughly analyzed, highlighting the potential and future directions for developing anti-corrosion and protective coatings using DES-assisted electroplating techniques.

Abstract: With the rapid rise in portable electronic and wearable devices, safety concerns have become a global research focus. Gel polymer electrolytes (GPEs) offer a safer and more adaptable alternative to conventional liquid electrolytes, enabling the design of flexible energy storage systems (ESS). Combining viscoelasticity with metallic, semiconductor, and organic components, GPEs have emerged as key materials for advanced ESS applications. This review provides a comprehensive summary of recent progress in GPEs, emphasizing their enhanced physicochemical properties and electrochemical performance. Key topics include the concept of unity lithium-ion transference number and pseudocapacitance, as well as advancements in smart GPEs with self-healing, thermotolerant, and self-protection capabilities. The review concludes by discussing prospects and challenges for future research on GPEs, aiming to propel next-generation energy storage systems.

Abstract: We conducted a theoretical and experimental study on the electro-oxidation of methanol (MOR) on NixPdy nanoparticles. The results are presented in terms of kinetic parameters, surface concentrations and peak currents, showing significant differences between three main compositions: Ni3Pd1, Ni1Pd1 and Ni1Pd3. The kinetic mechanism adopted for accounting the linear voltammetry experiments performed follows the carbonate-palladium oxide pathway of the MOR. Numerical simulations of the kinetic equations, fitted to experimental data obtained at varying methanol concentrations, allowed us to distinguish the adsorption contributions of methanol, water, and OH ions from the nonlinear contribution associated with palladium oxide and carbon dioxide production. The synergistic effects of Ni:Pd nanoalloys on the MOR are then assessed by analyzing the behavior and tendencies of the reaction rate constants for different bulk methanol concentrations. Our results suggest that a higher Pd content favors more efficient oxidation mechanisms, by reducing the formation of intermediate products that cause surface poisoning, such as CO, carbonates or palladium oxide. However, as the proportion of Ni increases, an increase in the concentration of adsorbed OH is observed, which dominates the blocking of active sites even above from the palladium oxide blocking.

Abstract: The water-based binder has the advantages of non-toxic, non-flammable, small odor and no pollution to the environment. However, there are problems such as low bond strength and poor battery cycle life of commonly used binders on the market. In this paper, the acrylic binder is modified. Acrylic acid/methacrylic acid, acrylonitrile, and octadecyl acrylate/octadecyl methacrylate are copolymerized at high temperature, and a new binder for graphite anode is successfully developed. The binder can significantly improve the affinity between the graphite anode and the electrolyte and the integrity of the graphite particles during the cycle, so that the battery has better electrochemical performance. During the charge and discharge cycle of 1 C, the graphite anode coated with PAANa as a binder was able to cycle 360 cycles and remain stable, far better than the 192 cycles of the commercial binder LA133. It is proved that the experimental formula has a certain commercial application prospect.

Abstract:

Lipid peroxidation is a major process that determines the quality of various oil samples during their use and storage, in which the primary products are hydroperoxides (HP’S). HP’S are very stable compounds at ambient conditions and are harmful to human health. Therefore, the eval-uation of the degree of oil oxidation is an excellent tool for ensuring food safety. Тhe peroxide value (PV) is the main parameter for quality control of oils. Herein, we propose an alternative electrochemical method to the most widely used classical iodometric titration for determining the PV. Our approach is based on the electrochemical quantification of hydroperoxides/peroxides in an organic solvent medium (acetonitrile and organic ammonium salt) using a composite electro-catalyst-glassy carbon electrode modified with 2D-nanomaterial graphitic carbon nitride doped with Co3O4. Calibration was made by standard addition method using benzoyl peroxide (BPO) as a model peroxide compound, dissolved in chloroform and added to fresh Rivana brand an-ti-cellulite oil used as a model oil sample. Calibration plots showed a linear response and very good reproducibility of the analytical result (R2˃0.99). Further, in term of accuracy, the method showed good results, since the BPO quantitative analysis was close to the theoretical response. In addition, the accuracy of the electrochemical method was compared with that of the standard iodometric titration method for determining the PV of vegetable fats (according to Bulgarian State Standard, BSS EN ISO 3960:2017). Finally, using the electrochemical method, the concentration of peroxides was determined in a real sample - an anti-cellulite oil of the trademark Rivana with an expired shelf life.

Abstract: Polymer-based aqueous redox flow batteries (RFBs) are attracting increasing attention as a promising next-generation energy storage technology due to their potential for low cost and environmental friendliness. The search for new redox-active organic compounds for incorporation into polymer materials is ongoing, with anolyte-type compounds in high demand. In response to this need, we have synthesized and tested a range of new water-soluble redox-active s-tetrazine derivatives, including both low molecular weight compounds and polymers with different architectures. S-tetrazines are some of the smallest organic molecules that can undergo a reversible two-electron reduction in protic media, making them a promising candidate for anolyte applications. We have successfully modified linear polyacrylic acid and poly(N-isopropylacrylamide-co-acrylic acid) microgels with pendent 1,2,4,5-tetrazine groups. Electrochemical testing has shown that the new tetrazine-containing monomers, and importantly, the water-soluble redox polymers, both linear and microgel, demonstrate chemical reversibility of the reduction process in an aqueous solution containing acetate buffer. This expands the range of water-soluble anodic materials suitable for water-based organic RFBs. The reduction potential value can be adjusted by changing the substituents in the tetrazine core. It is also worth noting that the choice of electrode material plays an important role in the kinetics of the tetrazine reaction: the use of carbon electrodes is particularly beneficial.

Abstract: Monitoring creatinine levels in urine helps to recognize kidney dysfunction. In this research we have developed a photocurable membrane for the detection of serum creatinine. Using a system based on field-effect transistors, we carried out comparative tests of creatinine recognition in solutions prepared in different matrices. The device was able to detect creatinine in water, synthetic urine and pH 4 buffer from the lowest concentration tested (3 mmol L-1), covering values between 21 % and 31 % within the range of creatinine variation for healthy individuals (3-27 mmol L-1) with measurement linearity of 97 %. The LOD achieved in the test was 1.31 mmol L-1 under flow conditions. With LOQs between 4.34 mmol L-1 and 24.13 mmol L-1. The system performed very well in the measurements, with hysteresis ranging from 1.1 % to 8.6 % for the different matrices tested. Up to 90 days after manufacture, the sensor still maintained more than 70% of its initial response, even when used periodically during the first week and when stored unused at -18 ºC, it was able to maintain 96.7 % of its initial response. The device used in the flow test only had a useful life of three days due to membrane saturation, which was not reversible. In the interference test, the membrane was also shown to respond to the urea molecule, but in a different response window, which allowed the contributions of the two molecules to be differentiated. EGFETs can be used to identify variations in creatinine concentration and can help in therapeutic decision-making.

Abstract: Nowadays, there is a growing focus on sustainability, characterized by making changes that anticipate future needs and adapting them to present requirements. Sustainability is reflected in various areas of materials science as well. Thus, more research is focused on the fabrication of advanced materials based on earth-abundant metals. The role of iron and its compounds is particularly significant as iron is the second most abundant metal on our planet. Moreover, the electrochemical approach provides a rather eco-friendly way for versatile materials synthesis, including iron-based materials that can be found in various applications, due to a smart tuning of properties by codeposition of appropriate compounds with iron. Thus, highlighting and boosting its magnetic, catalytic, mechanical, antimicrobial/antibacterial properties, thermal, wear, and corrosion resistance. Among iron-based materials, those with refractory metals, including tungsten-based alloys, are widespread research fields with practical possibilities. Special attention in this review is devoted to peculiarities of electrodeposition from complexing electrolytes of such materials as they can meaningfully impact the final structure, content, and design of properties.