ChemElectroChem最新文献

Transition to a sustainable energy future demands the development of alternative battery technologies beyond lithium-ion batteries, which are challenging for large-scale implementation due to inherent safety concerns and resource scarcity. Aqueous zinc-ion batteries (ZIBs) are a promising solution; however, improvement of the cathode is essential for their widespread adoption. This study investigates the structural modification of zinc hexacyanoferrate (ZnHCF) as cathode materials using ball-milling and the addition of carbon black (Vulcan XC-72R). The improved electroactivity is attributed to the phase transition from cubic to rhombohedral, the conversion of Prussian blue analogue to Prussian white analogue phases, and the synergistic effect produced by the presence of carbon material. These changes lead to the formation of [Fe(CN)₆] vacancies, which draw water molecules into interstitial sites. Carbon material plays a crucial role in preserving the crystalline structure of ZnHCF and enhancing the electrochemical performance. The sample milled in presence of carbon material (BM-ZnHCF@C sample) demonstrates superior results compared to the samples unmilled and milled samples without carbon material, achieving a capacity close to 100 mAh g⁻¹ at a current density of 0.5 A g⁻¹. However, after 50 cycles, the capacity decreases by 53.3%, but is restored by replacing the Zn anode while retaining the same cathode. The zinc anode is the primary factor hindering the long-term performance of the assembled battery, as demonstrated by the evolution of the electrode potential over time in the ZIB using a T-type electrochemical cell.

Granular carbon-based cathodes in carbon dioxide-reducing bioelectrochemical systems (CO₂-reducing BES) feature high biocompatibility and stability. Wood-based biochar is gaining popularity in (bio)electrochemical applications due to its sustainability and reduced environmental impact. Yet, previous studies primarily examined lab-scale biochars. This study investigates how heterogeneity of industrial-scale granular biochars (GBs) influences their electrocatalytic activity for hydrogen evolution reaction (HER) in the nexus of CO₂-reducing BES. Significant variations are identified in overpotentials for HER at −1 mA cm⁻² (η_-1 mA cm⁻²) among the GB-based cathodes. Beechwood-derived GB pyrolyzed at 740 °C shows the lowest η_-1 mA cm⁻²(223.6 ± 30.0 mV), outperforming birchwood-derived GB at 700 °C (503.5 ± 4.9 mV) and granular graphite (608.3 ± 19.5 mV). Despite its superior performance, beechwood-based GB shows high heterogeneity. Such heterogeneity underlies different physicochemical properties, likely due to uneven temperature distribution in industrial pyrolysis. The remarkable performance of beechwood-based GB pyrolyzed at 740 °C is attributed to its higher electrical conductivity, higher degree of carbonization, favorable H/C ratios, higher disorder in carbonaceous structure, and suitable porosity. The results highlight the influence of the wood type, the importance of systematic GB characterization, and the necessity to optimize industrial-scale biochar production to achieve homogeneous and high-performance biochar.

Moving from planar electrodes to unique surface architectures can produce significant improvements in electrochemical performance. Herein, we report the inclusions of unique microstructures fabricated onto the electrode surface through printing them onto laser-engraved print beds modified with different patterns (lines, crosses, circles, waves, and unmodified surfaces). Unique surface architectures were successfully produced on the surface of additive manufactured working electrodes printed from both commercial and bespoke conductive poly(lactic acid) and bespoke poly(propylene) (B-PP) filaments. Within both poly(lactic acid) filaments, minimal alteration in performance was seen, proposed to be due to the ingress of solution negating the surface architecture. For the B-PP, which do not suffer from solution ingress, significant improvements in peak current and electrochemical area were found for all surface architectures against both inner and outer sphere redox probes, with a cross architecture producing the largest improvement. This was corroborated in the electroanalytical application, with electrodes with crosses surface architecture producing a 3-fold improvement in sensitivity, limit of detection, and limit of quantification when compared to electrodes with no additional surface architecture for the detection of acetaminophen. This work shows improvements in the electrochemical performance of additive manufactured electrodes can be achieved through simply modifying the print bed, without alterations to print files or post-print modification methods.

Inactive lithium (Li), often referred to as dead or isolated Li, consists of electrochemically disconnected metallic Li and Li-containing compounds trapped within or beneath the solid–electrolyte interphase (SEI). It is widely recognized as a primary failure mode in lithium-metal batteries (LMBs), contributing to performance degradation, safety concerns, and limited scalability. This review outlines the sequential processes of Li nucleation, growth of high-surface-area Li, and the formation of inactive Li, while identifying the key physicochemical factors influencing each stage. Li nucleation is governed by current density, temperature, electrolyte formulation, and interfacial properties, which collectively dictate the uniformity of Li plating. High-surface-area Li growth introduces mechanical and chemical instabilities, fractures and uneven stripping of these filamentous structures lead to Li isolation and inactive Li accumulation. To address these challenges, advanced characterization techniques, including solid-state nuclear magnetic resonance spectroscopy, titration gas chromatography, inductively coupled plasma optical emission spectroscopy, and operando synchrotron X-ray diffraction, offer critical insights into the formation and progression of inactive Li. Emerging reactivation strategies, such as redox mediators and tailored cycling protocols, show promise in recovering lost capacity. This review presents key mechanistic factors, advanced diagnostic tools, and emerging reactivation strategies to support a deeper understanding and control of failure mechanisms in LMBs systems.

Zinc–air batteries (ZABs) have attracted much attention because of their high energy density, low cost, and excellent safety. However, developing inexpensive oxygen electrocatalysts with stable performance and fast reaction kinetics remains challenging. Herein, a simple and versatile dual-template-assisted pyrolysis strategy to prepare iron-nitrogen co-doped porous carbon (R-Fe-N-C) catalysts using magnesium carbonate hydroxide (Mg₂(OH)₂CO₃) as a self-generated template, ferrocene as an iron source, ethylenediaminetetraacetic acid disodium zinc salt (EDTA-Na₂Zn) as a carbon source, and 1,10-phenanthroline as a nitrogen source is proposed. During the pyrolysis process, Mg₂(OH)₂CO₃ can be decomposed to generate MgO nanoparticles as self-generated hard template embedded in the carbon skeleton, and finally removed by acid etching to form a rich mesoporous structure. Meanwhile, the Zn species in EDTA-Na₂Zn can form rich micropores after high-temperature evaporation. Thus, the R-Fe-N-C catalyst reaches a high half-wave potential of 0.874 V and good stability, which is better than commercial Pt/C. In addition, ZABs with R-Fe-N-C as air cathode exhibit high open circuit voltage of 1.52 V and a maximum power density of 122.9 mW cm⁻², as well as good cycle stability over 110 hr. The proposed synthesis strategy provides an effective way for designing metal-heteroatomic-doped porous carbon materials.

Due to its high electrical conductivity and large specific surface area, graphene is a highly promising material for electrochemical energy storage applications. However, its practical use remains limited due to stability issues, primarily due to π–π stacking interactions between the graphene sheets. Herein, a graphene-based composite is reported that overcomes this limitation. This composite consists of reduced graphene oxide (rGO) decorated with polyoxometalate (POM) nanoclusters, [SiW₁₂O₄₀]⁴⁻. To obtain this composite, first, [SiW₁₂O₄₀]⁴⁻ ions are electrochemically reduced, then the solution is mixed with a suspension of graphene oxide (GO). The reduced POMs reduce GO and deposit on the graphene sheets, leading to a rGO@POM composite. The composite suspension could be drop casted onto an electrode without requiring binders. The interest of [SiW₁₂O₄₀]⁴⁻ is its reversible redox properties with the potentials in cathodic domain allowing to explore an unusual potential domain (1.6 V) in an aqueous electrolyte (Na₂SO₄/H₂SO₄, pH 4). This approach afforded a pseudocapacitive material with excellent stability, showing no capacitance loss over 20,000 cycles at 1 V•s⁻¹. Furthermore, the synergistic effect between the faradaic contributions due to [SiW₁₂O₄₀]⁴⁻ and the rGO capacitive behavior results in a high volumetric capacitance exceeding 300 F cm⁻³ and an outstanding energy density of 26 mWh cm⁻³.

Polymeric electrochromic devices (ECDs) can be used in a wide range of applications like smart windows or displays. For ideal electrochromic performance and stability, the charge balancing in these devices is crucial. In this study, roll-to-roll slot-die coating is used to prepare three film thicknesses of the in situ polymerized sidechain-modified poly(3,4-ethylenedioxythiophene) derivative PEDOT-EthC6 on indium tin oxide coated polyethylene terephthalate, ranging from approx. 100 nm to 170 nm. The PEDOT-EthC6 electrodes show transmittance modulations varying from τ_v = 31% ↔ 78% to τ_v = 13% ↔ 68%. Constant current constant voltage measurements reveal that the volumetric charge density increases with film thickness from 0.15 C cm⁻³ to 0.18 C cm⁻³. The three films are used in hybrid ECDs with Ni oxide as the counter electrode, where the PEDOT-EthC6 electrode is either under-dimensioned, matching, or over-dimensioned. The latter shows the largest transmittance modulation of τ_v = 12% ↔ 55%. Using three-electrode cells, it is found that the over-dimensioned PEDOT-EthC6 electrode limits the potential range of this electrode, preventing side reactions. Simultaneously, the potential window is widened at the Ni-oxide electrode, enabling it to be fully switched. The ECD shows good cycling stability over 5000 cycles at 25 °C and 65 °C.

This review showcases crucial factors in mechanisms of electrochemical CO₂ reduction by taking Pd-based electrocatalysts (mainly, monometallic Pd and Pd-based alloy nanoparticles) as examples. There are dependencies of experimental conditions (e.g., applied potentials) and constituent elements of the electrocatalysts on the reduction products of electrochemical CO₂ reduction. Moreover, Pd-based electrocatalysts have unique characteristics in electrochemical CO₂ reduction: alteration in selectivities for CO and HCOOH formations by applied potentials, almost no overpotential for HCOOH formation, deactivation of their electrocatalyses by poisoning with CO formed through CO₂ reduction, and in situ formation of palladium hydride. Here, we survey the characteristics of Pd-based electrocatalysts in terms of experimental and theoretical insights. Then, it is described that formation energies of intermediates estimated by density functional theory calculations are understandable factors to explain experimental performances of Pd-based electrocatalysts. Considering the estimated factors, this review exhibits a perspective of utilization of the factors to advance the research activity of electrochemical CO₂ reduction to its new horizon by using data science and high-throughput experiments.

Aromatic nitriles are extensively produced chemicals with a wide variety of applications. The high demand of these compounds justifies the search for sustainable synthesis alternatives using renewable energy. Here, an electrochemical oxidation of toluene and xylene derivatives to aromatic nitriles using NH₃ and H₂O under ambient conditions in a one-pot, two-step protocol is reported. In a first step, the toluene derivative is oxidized in the absence of a catalyst to the aldehyde. In the second step, ammonia is added together with LiI as an electrocatalyst to obtain the nitrile. The reaction network and mechanism are investigated using control experiments and cyclic voltammetry.

This study introduces a novel quasi-solid-state battery system as a proof of concept. A 55-nm solid-state electrolyte layer of lithium phosphorous oxynitride (LiPON) is deposited on slurry-based graphite electrodes and assembled against lithium metal to evaluate interfacial compatibility and electrochemical performance under controlled conditions. In contrast to thin-film quasi-solid-state batteries, this approach leverages a realistic electrode architecture, where LiPON adjusts to the rough surface of the slurry-cast graphite. By utilizing LiPON's dual functionality as both a solid-state electrolyte and a separator, the system eliminates the need for a conventional separator, while requiring only 5–10% of the liquid electrolyte used in equivalent systems. This design significantly reduces internal resistance and prevents contact loss during cyclic volume changes. Electrochemical analyses, including cyclic voltammetry, galvanostatic cycling, and impedance spectroscopy, demonstrate lithium intercalation stages consistent with those in liquid electrolyte-based systems, stable cycling behavior at room temperature and reduced electrode impedance of a few 10 Ω cm². Furthermore, X-ray photoelectron spectroscopy and scanning transmission electron microscopy confirm the formation of a solid–liquid electrolyte interface and the structural integrity of LiPON, which enhances charge transfer and long-term stability. These findings highlight the potential of quasi-solid-state batteries for safer, more compact, and cost-effective energy storage solutions.