ChemElectroChem最新文献

To provide a solid reference for the design of novel perovskite-oxide electrocatalysts for efficient water splitting, the fundamental HER and OER mechanisms, synthetic methods, tuning strategies, and material properties have been demonstrated in this review. In addition, the main challenges in further improving the material stability and electrocatalytic water splitting efficiency of current perovskite-oxide electrocatalysts for practical applications have also been discussed in detail. More details can be found in the Review by Bolong Huang and co-workers (DOI: 10.1002/celc.202400648).

Since the excessive exploitation of fossil fuels will cause wars for oil, developing sustainable and eco-friendly energy resources to solve the energy crisis and realize the carbon-neutrality goal has been a hot issue. Water electrolysis has been acknowledged as a promising technology for hydrogen (H₂)/oxygen (O₂) evolution reaction (HER/OER) since the overall water splitting reaction rates can be well controlled by applying appropriate electrode voltage. Whereas the sluggish electrochemical reactions kinetics on both the cathode and anode have greatly restricted the energy conversion efficiency. Thus, developing highly active electrocatalysts to reduce the overpotentials required for electrolytic HER/OER is of great significance in increasing the utilization rates of electrical power and lowering production costs. ABO₃-structured perovskite-oxides based electrocatalysts possess the merits of low cost, high structural stability, and lattice compatibility, and thus they have attracted intense research attention in recent decays. To inspire both theoretical and experimental researchers to design novel perovskite-oxide electrocatalysts for efficient HER/OER, the fundamental electrode reaction mechanisms, the effects of synthetic methods on material morphologies, recently reported perovskite-oxide electrocatalysts and effective tuning strategies on enhancing the electrocatalytic activities of existing perovskite-oxides have been fully discussed in this review.

The Front Cover illustrates crystal structures of inorganic solid electrolytes (ISEs) featuring exceptional Na⁺ ion conductivities at room temperature in solid-state sodium batteries (SSSB). Rational structural design and doping strategies can enhance the Na⁺ ion conductivity and electrochemical stability of ISEs. However, significant interfacial challenges remain for the practical implementation of SSSBs. More information can be found in the Review Article by Patrick Joohyun Kim, Junghyun Choi, and co-workers (10.1002/celc.202400612).

3Dtransition metal coordination clusters, as structurally diverse and designable metal-organic hybrid systems, enable deliberate modulation of active sites and bridging motifs within their structural kernels, making them ideal precursors for tailored nanostructures via pyrolysis. Through precise control over metal/organic ratios, the composition, spatial configuration, and electronic structure of derived nanomaterials can be effectively regulated, holding great promise for establishing structure-property relations and achieving optimized functional materials. In this review, nanostructures of Schiff base coordination clusters to control and optimize electrochemical energy storage/conversion performances. Specifically, coordination framework engineered clusters have been pyrolyzed into electrode materials for supercapacitors and electrocatalysts for oxygen/hydrogen evolution reactions, exhibiting significantly enhanced capacitance and catalytic activity. Furthermore, perspectives are provided on employing molecular-level design principles of clusters in combination with pyrolysis optimization to develop next-generation customized energy systems. Additional investigation into structure-performance interdependencies will shed light on targeted optimization of cluster-derived nanostructures.

A deeper understanding of electrified solid/liquid interfaces of polycrystalline materials is crucial for optimizing energy conversion and storage devices, such as fuel cells, electrolyzers, and supercapacitors. After more than a century of research, the double-layer capacitance (C_DL) has proven to be one of the few relatively easily experimentally accessible quantitative measures for characterizing such interfaces. However, despite their great importance, systematic C_DL measurements are still not frequently associated with other interfacial properties. This work investigates the effect of the electrolyte pH on the C_DL for polycrystalline platinum (Pt(pc)) and gold (Au(pc)) electrodes using cyclic voltammetry and impedance spectroscopy in acidic solutions with a pH ranging from 0 to 2 without adding any supporting electrolyte. Interestingly, under these conditions, the C_DL for the Pt(pc) electrode increases with increasing electrolyte pH, while the C_DL for the Au(pc) electrode shows the opposite trend. The increasing trend for Pt(pc) cannot be quantitatively described by the classical Stern model due to the stronger adsorption phenomenon on Pt surfaces. Moreover, positive linear trends with pH were found for the potentials of minimum C_DL values and the potentials of maximum entropy for both electrodes, which closely correlate with reaction activities. However, the transition potentials of the constant phase element exponent (an element commonly used to approximate the behavior of the double layer in experiments) are only observed for the Pt electrode due to the phase transitions within the hydrogen adsorption/desorption and double-layer regions. These findings pose an important step toward revealing the interplay between essential interfacial parameters, which is crucial for a complete understanding of the electrical double layer.

Electrochemical nitrate reduction reaction (NO₃⁻RR) represents a promising ammonia (NH₃) production approach and has garnered significant attention in recent years. Owing to the highly tunable electronic structures and physicochemical properties, alloy materials have emerged as highly efficient catalysts for electrochemical NO₃⁻RR. This review systematically examines the recent advancements in alloy catalysts including binary alloys and multi-metal alloys for electrochemical NO₃⁻RR, comprehensively analyzing their structure, catalytic activity, and the mechanisms for NO₃⁻RR. In addition, the relationship between alloy catalysts′ composition, active sites, and catalytic activity are described, aiming to elucidate the underlying principles for high catalytic activity and guide the rational design of future alloy catalysts. Finally, this review addresses the challenges of alloy catalysts and proposes directions for future research and development.

Mathematical models of voltammetric experiments commonly contain a singular point value for the reversible potential, whereas experimental data for surface-confined redox-active species is often interpreted to contain thermodynamic dispersion, meaning the population of molecules on the electrode possess a distribution of reversible potential values. Large amplitude ramped Fourier Transformed Alternating Current Voltammetry (FTacV), a technique in which a sinusoidal potential-time oscillation is overlaid onto a linear potential-time ramp, is known to provide access to higher order harmonic components that are largely devoid of non-Faradaic current. Initially, a theoretical study reveals that the use of very large amplitude sinusoidal oscillations reduces the apparent effects of thermodynamic dispersion; conversely, frequency can be varied to change the sensitivity of the measurement to kinetic dispersion. Subsequently, FTacV measurements are used to probe a highly thermodynamically dispersed surface-confined ferrocene derivative attached to a glassy carbon electrode, with amplitudes ranging from 25 to 300 mV and low frequency, which minimises the impact of kinetic dispersion. The results from the experimental study validate the theoretical predictions, demonstrating that we can vary the amplitude in FTacV experiments to tune in and out of thermodynamic dispersion.

The cycling performance of lithium-sulfur (Li−S) batteries is hampered by polysulfide dissolution which impacts the overall performance of Li−S batteries. Here we report the synthesis and characterization of polysulfide trapping cathode material for Li−S batteries based on Co₃O₄ nanocubes supported within a nitrogen-doped entangled graphene (Co₃O₄/NEGF). The highly porous conductive graphene network is shown to facilitate fast electron transport and ion diffusion while the nitrogen dopants and polar Co₃O₄ offer both abundant active sites for polysulfide conversion while promoting intermediate polysulfide binding. The porous structure allows for high sulfur loading of 76.4 wt % (S@Co₃O₄/NEGF), while efficiently accommodating volumetric expansion during charge-discharge. The Co₃O₄/NEGF cathode composite exhibited a high specific capacity of 1143 mAh g⁻¹ at a current density of C/20 and maintained a 79 % reversible capacity after 200 cycles at C/5.

Electrocarboxylation, the electrochemical addition of CO₂ to organic substrates using renewable energy, offers a promising approach for carbon capture and utilization. However, commercial viability remains limited due to poor product selectivity and yields. In this work, we investigate how the electrolysis mode – chronoamperometry (CA) versus chronopotentiometry (CP) – influences the electrocarboxylation mechanisms of phenyl-activated substrates, Benzaldehyde, Styrene, and Benzylbromide, on Lead electrodes. By employing cyclic voltammetry (CV), in situ FTIR, and bulk electrolysis, we explore how these modes affect product selectivity and reaction efficiency. Our results show that substrate-activated mechanisms, such as those observed for Benzaldehyde and Benzylbromide, achieve higher selectivity and reduced side-product formation under CA conditions, while CP leads to increased side reactions. In contrast, Styrene exhibits more complex behavior, with CP favoring di-carboxylation, while CA enhances mono-carboxylation. These findings highlight the significant impact of electrolysis mode on controlling electrocarboxylation pathways, providing valuable insights for optimizing selective and efficient synthesis processes.

Sodium-ion batteries (NIBs) have gained significant attention in recent years due to the global abundance and cost-effectiveness of sodium, making them a promising alternative to lithium-based batteries. In this study, nitrogen-doped graphene oxide powders (NGO) have been prepared in one step by using chronoamperometric method and then have been used as anode materials for NIBs. The NGO powder surface is covalently doped by C−N formation. The synthesized powder had few layers (~3 layers) with nanocrystalline domain size (Lα) ~46 nm, and the number of sp² carbon rings was calculated to be ~18. The initial discharge capacity recorded 199.8 mAh g⁻¹ at 0.1 C rate. Besides, the capacity retention for long-term cycling of 100 cycles at 2 C rate was 91.78 %. The deduced diffusion coefficient from galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) measurements for NGO as anode in NIBs is in the range of 10⁻¹¹–10⁻¹² cm² s⁻¹. The electrochemical performance was attributed to the enhanced d-spacing of NGO up to 6.8 °A and formation large number of defects.