Journal of Solid State Electrochemistry最新文献

The discovery of new materials for electrochemical CO₂ reduction can take inspiration from biology and geology. Indeed, in the context of the hydrothermal vent theory of the Emergence of Life, alkaline vents represent a system of significant interest. These vents involve an alkaline, H₂ and HS⁻ rich fluid that meets the carbonic acidulous primordial ocean, resulting in the precipitation of a mineral barrier composed of iron sulfides and oxyhydroxides. This inorganic membrane separates the two fluids, generating an electrochemical potential difference. This ΔE can be dissipated by coupling CO₂ reduction (on the acidic side) with H₂ or HS-oxidation (on the alkaline side), potentially leading to the generation of the very first organic molecules on Earth. In this study, mackinawite [FeS_m] and violarite [Fe,Ni)₃S₄] were synthesized through homogeneous precipitation, their structures and electrochemical properties were characterized. Electrodes based on these materials were prepared and tested for CO₂ reduction. It was found that FeS_m can reduce CO₂ to formic acid and methanol, while (Fe,Ni)₃S₄ preferentially generates formic acid and carbon monoxide at − 0.82 V vs RHE. The results also indicate that very low overpotential is required for HCOOH generation on mackinawite. The proof that CO₂ reduction under these conditions occurs electrochemically, rather than purely chemically, is evidenced by the absence of CO₂ reduction products without the application of an electrical bias. Although the efficiency of these materials is currently limited, the potential for CO₂ reduction using earth-abundant elements such as iron, nickel, and sulfur is promising. Further engineering of these materials could lead to cost-effective technology.

This study investigates the effects of annealing and of chelating agents, triethanolamine (TEA) and ethylenediaminetetraacetic acid (EDTA), on tin sulfide (SnS) thin films prepared by potentiostatic electrodeposition on ITO-coated glass substrates. The films were annealed at 250 °C for 30 min, under air and under the presence of sulfur. The cyclic voltammetry revealed that the chelating agent’s type impacts the kinetic parameters of the deposition process. It was found that EDTA leads to stable chelates with tin ions compared to the TEA agent. Moreover, chronoamperometry highlighted that TEA enhanced the film’s electrochemical deposition kinetics, resulting in thicker and more compact layers when compared to those achieved with EDTA. XRD analysis showed the successful deposition of orthorhombic SnS films and the improvement of crystallinity by the increase of crystallite size after annealing treatments, especially with sulfurization. Raman spectra confirmed the deposition of pure SnS without annealing, and when annealing, the formation of a small amount of SnS₂ and Sn₂S₃ tin sulfide’s secondary phases. SEM micrographs revealed grain growth and densification. EDX analysis highlighted that both chelating agents and annealing processes affect the elemental composition of the films. Finally, optical studies have demonstrated that annealing increases the band gap energy, and TEA-based films are better for photovoltaic applications.

To extract Lu from LiCl–KCl molten salt, the electrochemical behavior of Lu(III) were explored by different electrochemical methods. Cyclic voltammetry (CV), reverse chronopotentiometry (RCP) and square-wave voltammetry (SWV) demonstrated that Lu metal was formed by one-step three-electron transfer when Lu(III) was reduced on W electrode, and the electrode reaction is reversible controlled by diffusion. The diffusion coefficient of Lu(III) in molten salt was calculated to be 1.68 × 10^–5 cm² s⁻¹ by SWV. Only BiLu was formed when the co-deposition of Lu(III) and Bi(III) was conducted at 773 K, which was confirmed by anode chronopotentiometry. The influence of temperature on the types of Bi-Lu intermetallic compounds was also explored. In addition, the thermodynamic parameters of BiLu were estimated by open circuit chronopotentiometry. The extraction efficiency of Lu(III) reach up to 89.54% when the constant-current electrolysis continued for 12 h based on the result of ICP-OES, and the product was characterized by SEM–EDS.

The series of the Fe_xTi_2-2xNb_10+xO₂₉ solid solutions (x = 0.0, 0.4, 0.5, 0.6, 1.0) with the monoclinic Wadsley-Roth crystallographic shear structure were prepared by the mechanochemically assisted solid-state synthesis and studied as anode materials for lithium-ion batteries. The phase purity of the synthesized samples was confirmed by X-ray powder diffraction and Mössbauer spectroscopy. The galvanostatic intermittent titration technique (GITT) results show that with an increase in the iron content in Fe_xTi_2-2xNb_10+xO₂₉, the Li⁺ diffusion coefficient, D_Li+, increases at the plateau region at 1.67 V, whereas it decreases in the region at 1.5–1.2 V. Fe_0.5TiNb_10.5O₂₉ represents a compromise between these two correlations; therefore, this sample has the highest average D_Li+ among the other Fe_xTi_2-2xNb_10+xO₂₉ samples. Therefore, the optimal composition, Fe_0.5TiNb_10.5O₂₉, exhibits the value of the specific charge capacity of 230 and 197 mAh g⁻¹ at the cycling rates of 10C and 20C, respectively, which is higher than those of Ti₂Nb₁₀O₂₉ (167 and 93 mAh g⁻¹) and FeNb₁₁O₂₉ (157 and 80 mAh g⁻¹). 

Graphical abstract

Applicability of a self-powered cascade bipolar electrode system for driving chemical charge transfer reactions (which under typical conditions do not occur spontaneously) was tested. As a proof of concept, oxidation of silver to silver ions was studied because the controlled release of small amounts of silver ions is of practical significance, e.g., due to their antibacterial activity. Since bacterial infection results in local acidification, effective bacteria killing by silver ions requires “stimuli-pH responsive” silver ions releasing arrangements. The applied cascade system consists of two bipolar electrodes (circuits) arranged in closed mode. One of the circuits, the “driving” one, is characterized by a high potential difference between opposite ends of the electrode (zinc wire connected with platinum electrode in the presence of hydrogen ions). Therefore, this bipolar electrode can trigger the silver oxidation process at the second bipolar electrode (silver/silver chloride electrode connected with silver wire). Cascade bipolar electrode architecture opens the possibility of tailored coupling chemical processes without need of electrochemical instrumentation. In the studied simple system, the process of silver oxidation can be effectively stimulated and controlled by the concentration of hydrogen ions contacting the platinum electrode, as a model of “stimuli-pH responsive” system, where lower pH actuates a higher rate of silver ion release. Electrochemical experiments were supplemented by quantification of silver and zinc released (ICP MS, UV/Vis). Basing on these results, some more general predictions concerning charge transfer reactions control and their sensitivity to external conditions for bipolar electrode systems were proposed.

A new composite based on V₂CT_x with a core–shell structure (Co-NCNT/VN/V₂CT_x) is prepared by a simple one-pot method. Dicyandiamide (DCD) is introduced as the dual-source precursor for both nitrogen and carbon, while Co(NO₃)₂ is added to catalyze the growth of Nitrogen-doped carbon nanotubes (N-CNTs) shell layer on the surface of V₂CT_x. After pyrolysis in a nitrogen atmosphere, the composite Co-NCNT/VN/V₂CT_x with a core–shell structure was obtained. The N-CNTs exhibit uniform growth morphology on the V₂CT_x layer and form a three-dimensional network configuration, which significantly enhances both the specific surface area (305.2 m²/g) and electrical conductivity of the material. The composite exhibits a specific capacitance of 862 F g⁻¹ when measured in 3 M KOH electrolyte. The voltage window ranges from -0.8 V to + 0.2 V, representing a 0.4 V expansion compared to that of pristine V₂CT_x. The electrode demonstrates exceptional cycling stability, with 95.6% of its initial capacity preserved after 10,000 cycles. An asymmetric supercapacitors is fabricated utilizing the composite material as the negative electrode, and the composite with Co–Ni layered double hydroxide (CoNi-LDH@Co-NCNT/VN/V₂CT_x) as the positive electrode. The electrochemical performance of the device demonstrates a working potential range spanning from 0 to 1.6 V, achieving a specific capacitance of 282.4 F g^⁻1 under standard measurement conditions. Notably, the system delivers an impressive energy density of 30.9 Wh kg⁻¹ while maintaining a power density of 800 W kg⁻¹.

This study designed and fabricated the pouch-type lithium-ion battery capacitors (LIBCs) based on niobium pentoxide (Nb₂O₅) as anode, and a composite cathode mixing activated carbon (AC) and LiNi_0.5Co_0.2Mn_0.3O₂ (NCM), probing and showing the electrochemical performances of the simple modulation on the anode/cathode mass match (N/P ratio). It was discovered that this kind of LIBCs could combinate the characteristics of capacitor, battery, and pseudocapacitor. LIBC with the N/P ratio of 0.8 exhibited the most trend of capacitive feature with the maximum b-value of 0.7446 in cyclic voltammograms and displayed the best electrochemical performances for suitable voltage window among all LIBCs. Besides the highest voltage retention of 93.34% in self-discharge behavior, the good C-rate performance makes the energy retention of 83.02% at 10 C and 72.20% at 30 C, and provides the energy density of 97.81 Wh/kg at 96.94 W/kg and even provides a value of 70.54 Wh/kg at 2875.82 W/kg (based on the mass of active materials). The best temperature adaptability makes the minimum change rate of resistance (129.8%), the maximum retention of capacity (88.1%) and energy (87.6%) after rested in the high temperature of 60 °C for 30 days, and the effective output at the temperature of 55 °C, 25 °C, 0 °C, − 10 °C, and − 20 °C. The best long-time cycle performance makes the highest discharge capacity retention of 80.2% after 5500 cycles, and it is demonstrated that the main degradation mechanism should be attribute to loss of active material and loss of lithium inventory rather than the increase of internal resistance according to the incremental capacity analysis (ICA) and electrochemical impedance spectroscopy (EIS).