ChemElectroChem最新文献

The oxygen evolution reaction (OER) is a critical bottleneck in water-splitting technologies. Hence, developing efficient and stable OER electrocatalysts is one of the key parameters to improve this technology. Recently, MXenes such as Ti₃C₂T_x and V₂CT_x have shown promise as OER-enhancing additives when combined with transition metal oxides. However, MXene synthesis requires energy-intensive processes, and the materials are prone to oxidation in various environments, such as air, or during electrochemical reactions. While this oxidation is typically considered detrimental, this study investigates whether partially exfoliated and oxidized V₂CT_x can maintain or even enhance OER performance, potentially simplifying the synthesis requirements for V₂CT_x. In this study, V₂CT_x is intentionally oxidized and incorporated into CuCo-based composites at various loadings. X-ray diffraction and X-ray photoelectron spectroscopy confirm the presence of vanadium oxide species in the partially exfoliated and oxidized V₂CT_x. The electrochemical investigations reveal that the partially exfoliated and oxidized V₂CT_x enhances the OER performance compared to fresh V₂CT_x. These findings suggest that, unlike Ti₃C₂T_x, partially exfoliated and oxidized V₂CT_x retains its functionality in OER catalysis and even outperforms its fresh counterpart, providing a more accessible and efficient platform for water-splitting applications.

LiNi_0.9Mn_0.1O₂ (LNM91) cathode has attracted significant attention in lithium-ion batteries (LIBs) due to its high capacity and low cost. However, its poor electrochemical performance and thermal stability hinder its application in electric vehicles. To overcome these limitations, this study proposes a novel one-step solid-state method for doping Al³⁺ and Mg²⁺ into the Ni and Li sites of LNM91, respectively, by directly mixing hydroxide precursors followed by calcination. Unlike the pristine cathode, which exhibits obvious cracking, the resultant Al/Mg codoped LNM91 maintains its structural integrity well after 100 cycles. The capacity retention significantly increases from 78.5 to 93.0% after 100 cycles at 0.5 C. Mechanistic studies reveal that Al³⁺ stabilizes the oxygen framework through strong AlO bonds, while Mg²⁺ suppresses Li⁺/Ni²⁺ disorder via electrostatic repulsion. Their synergistic effect mitigates the detrimental H2-H3 phase transition and microcrack propagation, thereby bolstering rate capability and cycling performance. These results highlight the significance of Al/Mg codoping as a promising approach for developing high-performance cobalt-free and nickel-rich cathodes for LIBs.

Electrochemical urea synthesis (EUS) from CO₂ and nitrates has recently emerged as a more sustainable alternative to nitrogen fertilizers derived from fossil fuels. Indeed, using captured CO₂ and nitrates from wastewater can offer environmental benefits compared to conventional methods. On the road to EUS technology development, its accurate and reliable quantification is an undeniable cornerstone. As this field is still in its infancy, with very low product concentration and numerous side-products, EUS product quantification is challenging, with reported false positives and negatives. Despite the consensus that at least two methods ought to be used, the selection of the most suitable methods and quantification protocols is an open topic in the scientific community. This work presents a comparative study of the most common methods, highlighting their advantages, limitations, and recent developments, aiming to provide valuable insights to guide the advancement of this emerging field and facilitate the upscaling of sustainable fertilizer production.

Electrochemical water splitting provides a sustainable route for hydrogen production, yet its efficiency is largely constrained by the intrinsically sluggish kinetics of the oxygen evolution reaction (OER) at the anode. Cobalt-based perovskite oxides are promising OER electrocatalysts in alkaline solutions, but their performance strongly depends on crystal structure and electronic configuration. Herein, a phase engineering strategy based on thermal reduction in inert atmospheres, which transforms a hexagonal-structured perovskite with poor OER activity into a cubic-structured perovskite with markedly enhanced OER kinetics, is demonstrated. This cubic phase exhibits a reduced Co valence and increased oxygen vacancy concentration, leading to a 20-fold increase in intrinsic OER activity compared to the hexagonal precursor. Its performance also surpasses that of state-of-the-art perovskites and noble metal- and non-noble metal-based benchmarks. This work highlights phase transformation as a powerful approach to optimize perovskite oxides for efficient OER electrocatalysis.

Artificial enzymatic electrochemistry has emerged as an effective method to extend the catalytic abilities of enzymes, further increasing selectivity and efficiency, while also addressing limitations with stability, substrate scope, and reaction scale. Bioelectrochemical methods are powerful analytical tools to understand and optimize the structure and function of artificial enzymes. However, advancements in this field are hindered by the challenges of practical implementation and insufficient foundational knowledge required for effective integration of biological and electrochemical techniques. This review aims to provide clear examples of artificial enzymatic electrochemistry with an emphasis on the techniques and data that can be obtained for each example. Additionally, we provide an overview of enzymatic electrochemistry experimental design to encourage the incorporation of these techniques into future enzymology research. The review concludes by discussing the outlook and perspective on future opportunities for development.

Although next-generation sodium-ion batteries (SIBs) possess more stable cathode materials than lithium-ion batteries (LIBs), thermal runaway (TR) remains a critical barrier to SIB applications. To resolve this safety paradox, atomic-scale investigations are conducted on the O3-NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) cathode. Combining accelerating rate calorimetry (ARC) and transmission electron microscopy (TEM), the material-intrinsic resilience is decoupled from cell-level failure mechanisms. The ARC analysis revealed high safety metrics of the NFM/hard carbon pouch cells; specifically, the maximum TR temperature (T₃) stabilizes at ≈310 °C (vs. >800 °C in Ni-rich LIBs) and the TR onset time extends to ≈40 h. As demonstrated in the TEM analysis, the NFM cathode maintains its structural integrity at 310 °C under inert conditions, although post-TR cathodes undergo catastrophic “brush-like” fragmentation with rock-salt/spinel phase transformation. This degradation is mechanistically attributed to reductive attack by electrolyte decomposition products and anode-derived gases (H₂/CO), which overwhelm the inherent stability of the cathode. To guarantee the inherent safety of SIBs, SIB design based on cathode thermochemistry alone must shift to the co-optimization of flame-retardant electrolytes, gas scavengers, and anode passivation.

Galvanic replacement reaction (GRR) is an oxidation–reduction process triggered by an electrochemical potential difference between two metal species, and involves the concerted motion of electrons, atoms, and ions at different times and spatial scales. Despite extensive research, a fundamental question remains unanswered: How can the driving force, that is, the electrochemical potential, be mapped in real time when existing microscopic, optical, and X-ray methods cannot capture it? In this article, the most widely used and fascinating system: silver-gold, in which three silver atoms are replaced by one gold atom, despite silver and gold having almost identical atomic radii, is interrogated. The experimental time-dependent open-circuit potential (OCP(t)) data, as well as phenomenological and mathematical models, are leveraged to describe the dynamics of the GRR. Specifically, modified sigmoidal kinetic functions are proposed based on autocatalytic networks and enzyme cascades performing logic gates, in order to account for the offset and sharpness of the OCP(t) responses at different input concentrations. This allows quantifying, for the first time, the two highly sought-after kinetic parameters of the apparent rate constant and the midpoint growth time. This knowledge can inspire new explorations in GRR-derived syntheses involving different galvanic exchange ratios for new functional nanostructured materials.

M. Paul, A. Grimm, G. Simões Dos Reis, G. Manavalan, S. E S, M. Thyrel, S. Petnikota, “Activated Carbon from Birch Wood as an Electrode Material for Aluminum Batteries and Supercapacitors” ChemElectroChem 2025, 12, e202400549. https://doi.org/10.1002/celc.202400549.

In Paragraph 2 (“Biochar and CBW Preparation”) of the Materials and Methods section, reference [6a] is missing and should be included alongside reference [12]. Additionally, new references should be added as [12c], [12d], [12e], and [12f]. The authors have acknowledged an image compilation error in the subpanels of Figure 3 and have provided the original images to address this issue. They confirm that all experimental results and the corresponding conclusions presented in the paper remain valid and unaffected. The corrected versions of Figure 3c,d are provided below.

Corrected Figure 3c,d;

The scaling of Y-axes provided for better understanding and visualization.

The authors apologize for this error.

References

[12c] G. Li, A. Lakunkov, N. Boulanger, O. A. Lazar, Oana, M. Enachescu, A. Grimm, A. V. Talyzin, “Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure”, RSC Advances, 2023, 13, 14543–14553, https://doi.org/10.1039/D3RA00820G.

[12d] A. Nordenström, N. Boulanger, A. Lakunkov, G. Li, R. Mysyk, G. Bracciale, P. Bondavalli, A. V. Talyzin, “High-surface-area activated carbon from pine cones for semi-industrial spray deposition of supercapacitor electrodes”, Nanoscale Advances, 2022, 4, 4689–4700, https://doi.org/10.1039/D2NA00362G.

[12e] N. Boulanger, V. Skrypnychuk, A. Nordenström, G. Moreno-Fernández, M. Granados-Moreno, D. Carriazo, R. Mysyk, G. Bracciale, P. Bondavalli, A. V. Talyzin, “Spray Deposition of Supercapacitor Electrodes using Environmentally Friendly Aqueous Activated Graphene and Activated Carbon Dispersions for Industrial Implementation”, ChemElectroChem 2021, 8, 1349–1361, https://doi.org/10.1002/celc.202100235.

[12f] A. Lakunkov, V. Skrypnychuk, A. Nordenström, E. A. Shilayeva, M. Korobov, M. Prodana, M. Enachescu, S. H. Larsson, A. V. Talyzin, “Activated graphene as a material for supercapacitor electrodes: effects of surface area, pore size distribution and hydrophilicity”, Physical Chemistry Chemical Physics, 2019, 21, 17901–17912, https://doi.org/10.1039/C9CP03327K.

As a key parameter, pH has received a lot of attention from the sensing perspective. New materials and technologies are being used to produce state of the art devices capable of tracking it. However, most generic sensors lack the applicability that certain applications require. In this article, 3D printing technology is used to its full potential to produce electrodes, which are modified into pH sensors and reference electrodes, with shapre-driven additional functionality for monitoring ammonia recovery in a bioreactor. The 3D-printed electrodes are modified with a layer of iridium oxide to be turned into pH sensitive devices. Their characterization showed their characteristic super-Nernstian response (−77 ± 0.2 mV pH⁻¹), high reproducibility (RSD < 5%) between sensors and repeatability (RSD < 2%) between measurements. Moreover, the sensors are stable for at least 20 days and tunable in length. All of this results in the sensors being built into a functional shape and tested to monitor the performance of an ammonia-producing bioelectrochemical reactor.

Developing efficient, acid-stable, and noncritical oxygen evolution reaction (OER) catalysts is crucial for the advancement of multiple renewable energy technologies. In this work, the design and synthesis of manganese oxide-based catalysts (MnO_x) are investigated, combined with varying ratios of gold nanowires (Au NWs)—both considered noncritical raw materials—to fabricate composite materials for use in acidic OER. The experimental findings indicate that approximately two-thirds of MnO_x within the catalyst layer is fully utilized when Mn is present at an atomic ratio of 5:1 to Au. This is primarily attributed to the incorporation of Au NWs, which markedly improves the conductivity of the catalyst layer. Cyclic voltammetry analyses suggest that in the composite with an atomic ratio of 5 Mn to 1 Au, Mn³⁺ remains persistently present on the surface of MnO_x throughout testing. This not only maintains the enhanced OER activity, but also significantly reduces Mn dissolution. Moreover, gas diffusion electrode measurements demonstrate that the “5Mn + 1Au” composite can achieve a current density of 1000 mA cm⁻². This observation reinforces the concept of employing composite electrocatalysts derived from noncritical raw materials and highlights their potential for catalyzing the OER in acidic environments.