ChemElectroChem最新文献

Solid-state batteries represent a new approach to energy storage, offering superior safety, higher energy density, and extended cycle life compared to conventional liquid electrolyte-based lithium-ion batteries. However, the practical application of solid-state batteries is hindered by degradation phenomena, particularly on interfaces between components, compromising their long-term performance. In this work, the kinetics of the state-of-charge-dependent electrolyte degradation at the LiNi_0.83Co_0.11Mn_0.06O₂│Li₆PS₅Cl interface, as well as its influence on cycling performance, are systematically studied electrochemically in solid-state battery half cells. Combining cycling and C-rate experiments with electrochemical impedance spectroscopy reveals that half cells charged to higher cutoff potentials (≥3.8 V versus In/InLi; ≥4.4 V versus Li⁺/Li) exhibit significantly faster degradation kinetics. These influence the cycling performance leading to a plateau in the charge capacity at ≥3.8 V versus In/InLi, while the electrolyte degradation does not affect the bulk electrode transport. Overall, this work emphasizes the importance to investigate state-of-charge-dependent decomposition kinetics in composite electrodes to better understand cycling behavior.

Global warming necessitates sustainable energy storage systems like aqueous Zn-ion batteries. Copper hexacyanoferrate (CuHCF) is a cost-effective, easily synthesized cathode material. Generally, a three-electrode setup containing a reference electrode (e.g., Ag/AgCl or SCE) is used to study the active material. Herein, it is shown that the presence of the reference electrode can interfere with the aging and cycle life of the active material through ions leaked from the reference's solution. Potassium leakage reduces CuHCF lifespan at high levels but slightly improves it at low levels, while sodium leakage shows weaker effects overall. Sodium-based reference solutions yield more reliable results, whereas potassium contamination risks misleading measurements.

Dye-sensitized photoelectrochemical cells (DSPECs) for water splitting into hydrogen and oxygen represent a promising approach to storing solar energy in chemical bonds. The surface-immobilized catalyst plays a crucial role in DSPEC performance. However, the water oxidation process requires substantial energy to break OH bonds, resulting in sluggish reaction kinetics. Consequently, depositing highly efficient and durable molecular water oxidation catalysts onto metal oxide surfaces presents a significant research challenge. Here, this study introduces a ruthenium-based pyridine water oxidation complex featuring a bds²⁻ ligand (bds²⁻ = 2,2′-bipyridine-6,6′-disulfonate) and a silatrane anchoring group for stable attachment to metal oxide semiconductors, forming a robust single-site heterogeneous catalyst. In pH 7 aqueous solution, the resulting Ru-bds (F-doped tin oxide/nanoATO/2C-bds). catalyst achieves a stable current density of 0.89 mA cm⁻² and a turnover frequency of 5.1 s⁻¹ over a 2 h test under an applied bias of 1.6 V versus normal hydrogen electrode. A variety of Ru-oxo intermediates generated during water oxidation are analyzed using in situ ultraviolet-visible, Raman, and infrared spectroscopies. These techniques provide data that support the proposed mechanism of heterogeneous water oxidation over Ru-bds catalysts. This work presents a streamlined strategy for designing stable, single-site heterogeneous catalysts for efficient solar-driven water oxidation.

Conventional electrochemical experiments can only obtain the average contribution of all active sites in the catalyst. Hence, it is meaningful to distinguish the electrochemical contribution of the local active sites in single-crystal catalysts. Here, a double-hole patch clamp is designed to achieve a localized electrochemical measurement in a model catalyst, MoS₂. The double-hole patch clamp is further applied to measure the hydrogen evolution reaction of MoS₂. By increasing the MoS₂ thickness from monolayer to bilayer, the onset potential increases from 156 to 238 mV. There is no obvious electrocatalytic reaction by further increasing the MoS₂ thickness to the trilayer. This could contribute to the ≈2.1 eV out-of-plane bandgap and corresponding high vertical resistance of MoS₂. This double-hole patch clamp provides a new tool to understand the electrocatalysis activities of the local active sites.

Porphyrin/sulphonated polyetheretherketone (sPEEK) composites are successfully obtained at different dye/polymer weight/weight percentage taking advantage of electrostatic interactions among the protonable nitrogen atoms of 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin porphyrin (TPyP) and anionic sulphonated groups of the polymer with 65% of sulfonation degree. These supramolecular adducts(TPyP-sPEEK) are drop-casted onto a commercial screen-printed carbon substrate (SPCE) to fabricate new modified TPyP-sPEEK /SPCE sensors for the detection of heavy metal ions such as Pb²⁺, Cd²⁺, and Hg²⁺. Sample at different porphyrin loads has been analyzed by electrochemical techniques. sPEEK composite with 5% porphyrin/polymer w/w% is identified as the optimal one in terms of stability and high percentages of recovery of the tested heavy metal ions in seawater environment.

Numerical modeling of bimetallic (BM) alloyed core-shell catalyst degradation is particularly important, since it enables the evaluation of the complex interplay between the shell thickness-dependent specific activity (SA), the resistance to electrochemical degradation, and the derivation of mitigation of poisoning resulting from dissolution of the alloying metal. Current state-of-the-art BM particle degradation models rely on a discrete approach, which is restricted to the simulation of a limited selection of core-shell particles rather than a full 2D distribution. In this study these challenges are overcome by developing a new BM catalyst degradation model based on the continuity equation and the rate of change of particle radii. Its applicability has been demonstrated by modeling the evolution of a 2D distribution of core and shell nanoparticles, and evaluating the loss of catalyst activity, not only in terms of changes in the catalyst's surface area, but also due to shell thickness-dependent SA variation. These new features of the model are further utilized to design a degradation mitigation strategy based on mixing BM and pure platinum catalysts in order to limit the alloying metal dissolution, as well as to minimize the loss of electrochemical activity.

Implementing electrochemical CO₂ reduction can decarbonize practical chemical and fuel production. However, in a typical CO₂ electrolyzer, electrochemical CO₂ capture (i.e., CO₂ reacts with electrochemically produced OH⁻ to form (bi)carbonates that are subsequently regenerated to CO₂ by the H⁺ flux in the reactor) commences in parallel with its electroreduction. Such a phenomenon is observed in various electrolyzer configurations with different electrolyte compositions. This concept begins with a brief discussion on how CO₂ capture occurs in CO₂ electrolyzers and focuses on the impact of CO₂ regeneration locations, including the anode, the electrolyte, and the ion-exchange membrane, on CO₂ electrolysis performance. It is shown that the key to overcoming the low CO₂ utilization and operational lifetime is positioning CO₂ regeneration on ion-exchange membranes. The goal is to highlight the essential role of the ion flow management approach in designing high-performance CO₂ electrolyzers. It would contribute to commercializing CO₂ electrolyzers for carbon-neutral chemical synthesis.

Electrocatalytic selectivity is generally explained in terms of atomic-scale properties, i.e., active sites, overlooking the impact of macroscopic electrode geometry and structure, which affect the macroscopic mass transport. This study demonstrates how the geometry of additively manufactured (AM) nickel electrodes fabricated via laser powder bed fusion influences reaction selectivity and the conversion rate of the glycerol oxidation reaction. All six AM electrodes with different geometries exhibit formic acid selectivity above 80%, with the large grid electrode achieving 95%. The large grid has deeper cavities and confined structures that promote enhanced oxidation due to restricted diffusion of C₂ and C₃ intermediates toward the bulk of the solution. The highest glycerol conversion of 28.2% is achieved with a 99% carbon balance, confirming efficient mass utilization. While achieving 100% formic acid yield remains challenging, minor byproducts are limited to ≤5%. These results emphasize that electrode geometry can be strategically tailored to optimize selectivity and enhance conversion efficiency. The significance of structural effects in electrocatalytic reactions is highlighted, providing novel insights into electrode design.

This study presents all-pseudocapacitive asymmetric supercapacitors (ASCs) operating in a neutral aqueous electrolyte. Hydrothermal approach is selected for the synthesis of the active electrode materials for ASC. Fe₂O₃ and N-doped reduced graphene oxide (N-rGO) composites are used for negative electrode, while MnO₂ and N-rGO composite is used for the positive electrode. The Fe₂O₃ content in the binary composite influences the porosity, morphology, and surface chemistry of the negative electrode material, which further impacts electrochemical performance and cyclic stability of the assembled ASCs. The studies show that graphene-based composites used as a negative electrode should exhibit appropriate porous structure in order to prevent undesired parasitic side reactions. The fabricated ASCs deliver high energy density up to 25.3 Wh kg⁻¹ density at a power density of 205 W kg⁻¹ when operated at 2 V in 1 M Na₂SO₄. The most stable configuration maintains almost 94% of the initial capacitance after 10 000 charge–discharge cycles. These components demonstrate the potential to fabricate environment-friendly, efficient, and reliable energy storage devices when combined in the proposed configuration with binary Fe₂O₃ (FNG) and MnO₂ (MNG) composites and a neutral aqueous electrolyte.

Organic redox species are used in redox flow batteries, redox-mediated CO₂ capture, and catalysis. Organic molecules with high redox potentials, e.g., TEMPO, have found use as oxidation agents and as catalysts in organic chemistry. This study presents a synthesis route to make new organic redox-active molecule, 1,4-diallyl-2,5-bis(allyloxy)benzene. The compound is electrochemically reversible with a formal redox potential of +1.45 V/standard hydrogen electrode (SHE). To unveil the electrochemical reaction mechanism of 1,4-diallyl-2,5-bis(allyloxy)benzene, a series of different organic molecules are synthesized and electrochemically characterized. Together with a series of chemical oxidation experiments supported by NMR, the electrochemical mechanism of the quasi-reversible electron transfer is suggested. The oxidation of 1,4-diallyl-2,5-bis(allyloxy)benzene leads to a formation of an organic cation radical, which is stabilized by allyl groups, and can be reverted to upon electrochemical reduction. Overall, 1,4-diallyl-2,5-bis(allyloxy)benzene is a new, electrochemically quasi-reversible redox molecule, with a very high redox potential, that can find application in redox flow batteries, catalysis, and organic chemistry, as oxidant.