Journal of Applied Electrochemistry

Paulsingh, Pauline Ida; Michael, M. S.

doi: 10.1007/s10800-025-02322-0pmid: N/A

Polymer electrolytes are much of interest for the development of flexible Na-based energy storage systems with desirable structure design and safety. However, the low ionic conductivity at ambient temperature, poor mechanical strength and high interfacial resistance of solid polymer electrolytes (SPEs) hinder their wide applications. Novel strategies like cross-linking polymer matrices, binary salt systems and incorporation of additives such as plasticizers, nanomaterials, ionic liquids and inorganic filler paving the way for improvement of electrochemical and mechanical properties of polymer electrolytes. This mini-review provides a comprehensive overview of various types of polymer electrolytes, namely solid, gel and composite developed for sodium-based energy storage systems. The review highlights the key performance aspects, namely ionic conductivity and electrochemical stability and mechanical strength which are essential for improving the efficiency and longevity of these devices. Furthermore, recent advancements in biopolymer-based renewable polymer electrolytes, focusing on their potential applications in flexible sodium-ion batteries and sodium-ion capacitors are discussed.Graphical abstract[graphic not available: see fulltext]

Fernández-Velayos, Sergio; Oliveira, Kaíque S. G. C.; dos Santos, Elisama Vieira; Martínez-Huitle, Carlos A.

doi: 10.1007/s10800-025-02321-1pmid: N/A

Oxidants such as peroxocompounds are commonly used in various applications, including wastewater treatment, soil remediation, and synthesis of high-added value products. In recent years, the electrochemical synthesis of oxidants has emerged as a sustainable approach, driven by the development of new anodes, such as boron-doped diamond films. Typically, electrochemically produced oxidants generated at boron-doped diamond anodes are used in situ, with both generation and application occurring simultaneously. This perspective explores the possibility of electroproducing oxidants for subsequent ex-cell applications. For such applications, the stability of the oxidant is a critical factor to consider. Electroproduced oxidants, such as peroxodisulfate, chlorine dioxide, or ferrate anions, have been successfully used ex-cell for the efficient removal of emerging contaminants from water. Additionally, studies highlight the effectiveness of ex situ applications of these oxidants in soil remediation, showing good performance both through direct soil treatment and the treatment of leachate from soil washing. Finally, electrochemically produced peroxodicarbonate and periodate have been used in the synthesis of high-added value organic compounds, with demonstrated applications in reactions, such as N- and S-oxidation, epoxidations, and vanillin synthesis.Graphical Abstract[graphic not available: see fulltext]

Vimala, V.; Renugadevi, C.; Sivasakthi, S.; Cindrella, L.

doi: 10.1007/s10800-025-02316-ypmid: N/A

In this study, sulfur and nitrogen heteroatoms were successfully doped into reduced graphene oxide (rGO) through a controlled pyrolysis process, yielding materials with outstanding electrochemical performance. Raman spectroscopy revealed the effective reduction of graphene oxide, as evidenced by shifts in the positions of the D and G bands and the variation in intensity with an increase in defects. Furthermore, X-ray photoelectron spectroscopy and Fourier-Transform infrared spectroscopy analyses confirmed the incorporation of sulfur and nitrogen atoms into the rGO framework. Electrochemical evaluation, conducted in a 0.5 M Na2SO4 electrolyte, showed a remarkable-specific capacitance of 448.7 F g−1 at 1 A g−1. The material also exhibited exceptional cyclic stability, holding onto 91.01% and 42.68% of its capacitance after 1000 and 10000 cycles, respectively. This work underscores the potential of heteroatom doping as a transformative strategy for graphene-based materials, paving the way for high-performance electrodes in next-generation supercapacitors.Graphical abstract[graphic not available: see fulltext]

Lokhande, Prasad E.; Rednam, Udayabhaskar; Padalkar, Shailesh; Al-Asbahi, Bandar Ali

doi: 10.1007/s10800-025-02319-9pmid: N/A

In the present study, cerium oxide (CeO₂) was combined with nickel oxide (NiO) using a microwave-assisted method followed by post-annealing used for supercapacitor applications. The microwave-assisted method enabled rapid and uniform heating, which accelerated reaction kinetics and ensured precise nanostructure formation. Crystallographic and morphological analyses confirmed the formation of nanorod-like structures in the CeO₂–NiO nanocomposite without impurities. Electrochemical performance was evaluated using a three-electrode arrangement, revealing a maximum specific capacitance of 975 F g⁻1 at a current density of 2 A g⁻1, along with a low equivalent series resistance. An all-solid-state asymmetric supercapacitor was fabricated using the prepared material as the positive electrode, with activated carbon serving as the negative electrode. This device exhibited an energy density of 12 W h kg⁻1 and a power density of 2000 W kg⁻1, along with excellent cyclic stability, retaining 80% of its initial capacitance after 10,000 charge–discharge cycles. These findings highlight the enhanced electrochemical performance of the CeO₂–NiO nanocomposite and its potential for energy storage applications.Graphical abstract[graphic not available: see fulltext]

Singh, Alok Pratap; Deshpande, Uday; Ghosh, Susanta

doi: 10.1007/s10800-025-02309-xpmid: N/A

The exploration of suitable non-precious earth-abundant materials with sufficient active sites and their interaction with a suitable conducting support is very important for efficient water-splitting reactions to generate clean hydrogen fuel. The present study reports the in-situ growth of carbon supported cobalt sulfide (CoS) micro-structured crystals over graphite and copper sheets using a simple brush coated one-step calcinations technique and their electro-catalytic behavior towards oxygen evolution reaction (OER). Carbon supported powder CoS material was also synthesized under identical conditions in order to compare the performance with the material synthesized by in-situ technique. The electrochemical analysis demonstrates that the material grown in-situ over graphite/copper electrodes possesses better catalytic activities than the powder sample. The observed over-potential of the binder free self-supported film electrode for the oxygen evolution reaction (OER) was 270 mV compared to 413 mV for the powder sample to achieve the current density of 10 mA cm−2 in 1 M KOH solution. The synthesized carbon supported CoS materials were further characterized using various spectroscopic techniques, such as, XRD, FE-SEM, EDX and XPS. The long-term durability test of the carbon supported CoS/Gr material was conducted in alkaline medium to confirm its possible uses as a promising electrode material for the oxygen evolution reaction. The long-term stability over 16 h of the carbon supported CoS/Gr material was explained in terms of strong interaction between the active material and the conducting support.Graphical abstractA study of interaction between binders free self supported CoS films and the conducting graphite sheet for electrochemical oxygen evolution reaction[graphic not available: see fulltext]

Aziz, Majid; Amrite, Archis; Aryal, Utsav Raj; Prasad, Ajay K.

doi: 10.1007/s10800-025-02312-2pmid: N/A

The potential benefits of hydrogen as an energy carrier can only be realized when its production, storage, and distribution are accomplished in a sustainable, safe, and efficient manner. For numerous end-user applications, a convenient solution is to separate hydrogen from a mixture containing hydrogen and store it as a compressed gas. Electrochemical hydrogen separation and compression (ECHSC) represents a promising alternative to conventional hydrogen separators and compressors because it can purify and compress hydrogen simultaneously in a single step. Furthermore, ECHSC offers additional advantages such as higher efficiency, lack of moving parts, noiseless operation, and modularity. Here, experimental results on ECHSC performance are presented in three modes, viz. electrochemical hydrogen pumping, separation, and compression. Gas mixtures containing various volume fractions (75%:25%; 50%:50%; 25%:75%) of hydrogen in nitrogen, methane, and carbon dioxide were employed for separation and compression studies. Various operating parameters were explored to investigate ECHSC performance. The ECHSC outlet hydrogen purity exceeded 99% for all three H2–N2 and H2–CH4 inlet mixtures and 95% for all three H2–CO2 inlet mixtures. The study also revealed the effect of CO poisoning for the case of the H2–CO2 inlet mixture. The results suggest that ECHSC is a viable alternative to conventional technologies for hydrogen separation and compression.Graphical Abstract[graphic not available: see fulltext]

Soler, Ignacio; Orts, Francisco; Molina, Javier; Micó-Vicent, Bàrbara; Bonastre, José; Cases, Francisco

doi: 10.1007/s10800-025-02313-1pmid: N/A

This research work studies the development of an electrochemical cell prototype based on textile electrodes for treating wastewater via electrochemical processes. The present prototype proposes a system that offers greater efficiency regarding the size/surface of electrodes in electrolysis processes. This prototype enables the treatment of large volumes of dissolution. Moreover, this prototype could surface modify textile electrodes by an electrochemical process in the same cell, specifically, an electrochemically reduced graphene oxide intermediate layer and an outer layer of electrochemically reduced metal nanoparticles are proposed. Surface modification by reduced graphene oxide increase the textile electrode’s stability, conductivity, and specific surface, whilst Pt nanoparticles increase electroactivity. Amaranth was selected to validate the use of this prototype in treating emerging pollutants. This is an azoic dye with a simple structure. Various analytical techniques demonstrate that colour removal takes place with an electrical energy consumption of between 0.29 and 4.66 kWh m−3 (depending on the operational specifications of the electrolysis performed). Once the colour is removed, total organic carbon and chemical oxygen demand decreases by up to 49% and 37%, respectively.Graphical abstract[graphic not available: see fulltext]

Acevedo-González, Alexis J.; Torres, Dinorah D. Martínez; Caicedo-Villamil, Jaileen R.; Rivera-Cruz, Oscar M.; Cabrera, Carlos R.

doi: 10.1007/s10800-025-02324-ypmid: N/A

The advancement of nuclear science and technology has resulted in the generation of increasing amounts of nuclear waste containing uranium, which poses severe risks to human health and the environment due to its high toxicity, radioactivity, and prolonged half-life. Effective remediation strategies are essential to mitigate these risks. This study presents a novel electrochemical approach for the remediation of uranium (VI) ions from aqueous media, utilizing nano zero-valent iron particles (nZVIs) incorporated onto a boron-doped diamond (BDD) electrode. The BDD electrode was modified with nZVIs prepared as an ink, and a 2.0 mM uranyl acetate dihydrate (UO2(C2H3O2)2·2H2O) solution in 0.10 M KClO4 served as the uranium (VI) source. Chronoamperometry was employed at a potential of -0.800 V vs. reversible hydrogen electrode for 40 min to facilitate the electrodeposition-based remediation of uranyl ions (UO22+). Comparative analysis was conducted using an unmodified BDD electrode to evaluate the remediation performance. Results revealed that the nZVIs/BDD system achieved a significantly higher removal of uranium (0.104 mg) compared to the unmodified BDD electrode (5.13 × 10−3 mg). Advanced characterization techniques, including cyclic voltammetry, scanning electron microscopy, and energy-dispersive X-ray fluorescence spectroscopy, confirmed uranium deposition, the formation of a thin layer on the nZVIs/BDD assembly, and the emergence of 3D structures on the unmodified BDD electrode. Raman spectroscopy identified the formation of different uranium oxides, UO2, UO3, and U3O8, on the nZVIs/BDD film surface and the unmodified BDD electrode during the electrochemical remediation process. These findings highlight the enhanced efficiency and efficacy of uranium (VI) electrochemical remediation facilitated by the nZVIs-modified BDD electrode.Graphical abstract[graphic not available: see fulltext]

Zhang, Na; Jiang, Wei; Shen, Mi

doi: 10.1007/s10800-025-02325-xpmid: N/A

The development of efficient, stable, and cost-effective multifunctional electrocatalysts was crucial for water electrolysis. This study introduced MoGe₂P₂As₂, a novel two-dimensional monolayer material with Janus semiconductor properties, derived from atomic doping of MoGe2N4. Various single-atom doped configurations (TM@MoGe₂P₂As₂, where TM = Fe, Co, Ni, Cu, Ru, Rh, Ag) were synthesized. Using Density Functional Theory (DFT), we analyzed their structural integrity, electronic properties, and catalytic efficiencies for the Hydrogen Evolution Reaction (HER), Oxygen Evolution Reaction (OER), and Oxygen Reduction Reaction (ORR). Notably, Ru@MoGe₂P₂As₂ exhibited exceptional trifunctional electrocatalytic performance, with a Gibbs free energy for HER of -0.13 eV (superior to platinum) and lower overpotentials for OER (0.12 V) and ORR (0.23 V). Its OER activity surpassed that of RuO2, and its ORR efficiency exceeded Pt (111). Furthermore, the application of volcano plots and the establishment of linear correlations between intermediate free energies validated ΔGOOH*-ΔGOH* and ΔGOH* as reliable descriptors for OER and ORR activities, respectively. Analysis of the d-band center theory and electronic structure provided deep insights into the underlying catalytic mechanisms. This research highlighted the potential of MoGe₂P₂As₂ based materials in designing next-generation multifunctional electrocatalysts, offering new perspectives for their practical applications.Graphical abstract[graphic not available: see fulltext]

Yipeng, Huang; Jun, Yang; Qingsheng, Liu

doi: 10.1007/s10800-025-02327-9pmid: N/A

In the Hall–Heroult process for primary aluminum production, the generation of anodic bubbles is an inherent phenomenon during electrolysis. This study investigated bubble dynamics and its impact on voltage drop in aluminum electrolysis cells. A bottom-observation transparent electrolysis cell was employed to enable direct visualization of gas evolution processes. Bubble nucleation, growth, coalescence, and detachment processes were recorded used high-speed cameras, and key parameters (size, coverage) were quantified through image analysis. The results showed that bubble growth preferentially occurred at localized surface regions over a short-term period. Coalescence between adjacent bubbles was identified as a dominant mechanism for bubble growth, which resulted in bubble diameters ranging from micrometric to millimetric scales. The bubble coverage exhibits a nonlinear decline with increasing current density, reaching a minimum value of 50% ± 2% at 0.9 A cm⁻2. This minimum coverage indicated a balance between bubble detachment and bubble generation. Synchronized voltage monitoring demonstrated a strong correlation between voltage fluctuations and bubble dynamics. The bubble-induced resistance was governed by both bubble coverage and bubble size, highlighting limitations in existing models that neglect bubble size effects.Graphical Abstract[graphic not available: see fulltext]