Electrochimica Acta最新文献

Photoelectrochemical (PEC) reduction of CO₂ is a promising strategy to convert CO₂ into chemical fuels for alleviating environmental crisis. However, modulation of photo-electrocatalytic processes to obtain a desired performance remains challenges due to the complicated PEC kinetics for CO₂ reduction. Herein, we present ZnTe/SnS₂ type II heterojunction photo-catalyst that facilitates light absorption for PEC reduction of CO₂ toward CO production with an improved selectivity and photo-stability compared to the pure ZnTe electrode. The study of charge transfer at the ZnTe/SnS₂ heterojunction interface with density functional theory (DFT) calculation and scanning electrochemical microscopy (SECM) characterization reveals that the photo-generated charge by ZnTe can flow quickly through the ZnTe/SnS₂ interface to participate CO₂ reduction reaction driven by the built-in electric potential of the type II heterojunction. The ZnTe/SnS₂ photocathode achieves a photocurrent density of 2.35 mA∙cm⁻² and a CO faradic efficiency of 87 % at −1.78 V (vs. Fc⁺/Fc) under standard illumination in a CO₂-saturated tetrabutylammonium hexafluorophosphate in acetonitrile electrolyte, and retains approximately 87 % of its initial photocurrent after one-hour of continuous illumination test. Consequently, a generation rate of 56.0 μM∙cm^−2∙h⁻¹ for CO can be obtained on this electrode.

The influence of a range of inter-electrode distances from 50 µm to 1 mm has been investigated for the first time, in order to assess to possibility to maximize the degradation and mineralization efficiency, while minimizing the cathode scaling and the inorganic by-products formation. Tylosin has been selected as representative pharmaceutical pollutant in wastewater, while the influence of Ca²⁺, HCO₃⁻/CO₃²⁻ and Cl⁻ was carried out. Advanced electro-oxidation with boron-doped diamond (BDD) anode and stainless-steel cathode was implemented to treat this synthetic effluent in a scalable filter-press reactor operated in a recirculated batch flow-by mode.

The first interesting feature is that cathodic OH⁻ and anodic H⁺ formations were not counterbalanced at short micro-distances (50 µm), meaning that electro-precipitation (until 50 % of CaCO₃ precipitation) and degradation/mineralization (until 100 %) could still occur at such range of distance. Secondly, the gain of mass transfer at the shorter distance (50 µm) couldn't counteract the higher energy needed to achieve similar degradation efficiency compared to the distances of 500 µm and 1 mm. Lastly, too high distances such as 1 mm suffer from lower mass transfer compared to sub-millimetric distances. Thus, an intermediate distance of 500 µm led to better performance in terms of tylosin degradation (100 % of degradation, 39 % of mineralization), while minimizing electro-precipitation (26 % of CaCO₃ cathodic precipitation) and unwanted inorganic chlorinated by-products formation (ClO₃⁻ = 2.8 mg L⁻¹). This was obtained at a current density of 0.1 mA cm⁻², leading to lower energy requirement (0.018 kWh g-tylosin⁻¹). In these low-current conditions the formation of perchlorate could be avoided.

Additives play a pivotal role in achieving high-quality electrodeposited cobalt films for diverse applications in microelectronics. In this work, 1,4-butynediol (BYD) bearing function groups of CC and -OH, 1,4-butenediol (BED) featuring C = C and -OH, and glycol (EG) with only -OH were studied to reveal the potential underlying mechanism of unsaturated carbon bonds on cobalt electrodeposition. It is found that BYD inhibits both the cobalt deposition and the formation of adsorbed hydrogen, forming compact cobalt film. Furthermore, the surface and cross-section morphology, grain structure, and resistivity of electrodeposited cobalt are characterized to investigate the effects of alkynol additives. It was observed that BYD induces a change in surface morphology from a mixture of elongated ridges and granular shapes to a flattened granular structure. The texture of the electrodeposited cobalt film transformed from hcp(100) and hcp(101) to hcp(002) with the addition of BYD due to the selective absorption of BYD on specific cobalt orientation. This study not only regulates the grains orientations and properties of electrodeposited cobalt, but also enhances the comprehension of the effect and mechanism of unsaturated carbon bonds on cobalt electrodeposition. These findings provide a theoretical foundation for the selection of additives and their practical applications.

All-solid-state lithium batteries (ASSLBs) are supposed to a highly forward-looking battery technology by reason of their conspicuous energy density and excellent safety. Ni-rich layered oxide cathodes have been extensively studied in ASSLB systems with sulfide electrolytes owing to their high voltage and preeminent specific capacity. However, the electrochemical performance of ASSLBs is severely degraded due to the interfacial physical contact failure, space charge layer effect, and chemical/electrochemical side reactions between sulfide electrolytes and Ni-rich oxide cathodes. In this work, the surface of LiNi_0.92Co_0.04Mn_0.04O₂ (NCM92) is coated with a nano-level CeO₂ buffer layer and is simultaneously doped with Ce element (NCM92–1%Ce) by one-step wet chemical method. Ce doping is beneficial for maintaining structural stability and suppressing irreversible phase transition. The CeO₂ buffer layer can efficaciously avoid the oxidation and decomposition phenomenon at the interface between NCM92 and sulfide electrolyte. As expected, NCM92–1%Ce cathode shows the discharge specific capacity of 141.46 mAh g⁻¹ after 80 cycles at 0.2C with 79.32% capacity retention rate, which is much higher than that of the unmodified NCM92 cathode. The results indicate that the surface-to-bulk synergistic modification strategy can successfully improve the structure toughness and interface stability of Ni-rich oxide cathode for ASSLBs with sulfide electrolytes.

Electrokinetic energy conversion (EEC) offers a promising avenue for transforming elusive natural energy into electric power, showing a wide application spectrum. Unlike prevalent studies that chiefly utilize symmetrical electrolyte solution (e.g., KCl) and uniformly structured negatively charged nanochannels for EEC, this paper delves into a thorough examination of EEC characteristics—streaming current, streaming potential, and output power—in both positively and negatively charged conical nanochannels with symmetrical and asymmetric (CaCl₂ and LaCl₃) electrolytes solutions. Operating under the assumption that the electrolyte solutions (KCl, CaCl₂, and LaCl₃) possess equivalent ionic strength and, thereby, a common Debye length, our findings reveal a significant dependency of EEC characteristics and their regulation parameters on the electrolyte type, nanochannel charge polarity, and ionic strength. As the ionic strength increases, both the streaming current and output power initially rise to a peak before subsequently declining, with the ionic strength at the peak being influenced by the cation valence: lower valence leads to lower ionic strength. In asymmetric electrolyte scenarios, optimal EEC characteristic is observed in positively charged conical nanochannels under a reverse pressure difference, attributed to the ion-selective and ionic concentration distribution in the charged conical nanochannels. Moreover, the complex behaviors of the regulation parameters of EEC characteristics are unveiled. Notably, a tri-valent electrolyte's regulation parameters exceed those of a bi-valent electrolyte, indicating that ionic valence asymmetry enhances the regulation effects on EEC in conical nanochannels.

A novel ultrasensitive nitrite ion detection using tungsten trioxide/carbon (WO₃/C) modified gold electrode has been studied. The WO₃ was synthesized from tungsten metal through chemical methods with selective precipitation techniques. The visual color of the material obtained is bright yellow, indicating WO₃ compound. The X-ray diffraction (XRD) diffractogram confirms WO₃ compound in monoclinic shaped by showing of the 2θ at 23.205, 23.723, 24.384, 33.426, and 33.911. The characterization using Field Emission Scanning Electron Microscopy (FESEM) showed that the material obtained was a disk-shaped with diameter 150–250 nm and a thickness of 50 nm. The Energy Dispersive X-ray spectroscopy (EDX) also confirms WO₃ compound with no impurities. The gold electrode was modified by dip immersion technique where the gold electrode was dipped in a mixture of WO₃-carbon paste. The measurement of surface area by cyclic voltammetry shows that the WO₃/C modified gold electrode has the highest surface area compared to unmodified gold and C-modified gold electrode, indicating it has more active electron transfer sites. The WO₃/C modified gold electrode worked well at pH 7 for the detection of nitrite ion and gave the highest peak current (0.875 V) than the others. The measurement ranges from 1–200 mg/L with no interference from ${\text{NO}}_3^{-}$, ${\text{SO}}_4^{2-}$, $Z{n}^{2+}$, $F{e}^{2+}$, $P{b}^{2+}$, $C{l}^{-}$, $C{a}^{2+}$, and ${\text{NH}}_4^{+}$ ions. The sensitivity and the LOD of the electrode are 8.86 μA.L.mg⁻¹.cm⁻² and 0.8 µg/L, respectively. The proposed method not only exhibits identical precision and accuracy to the standard method in detecting nitrite ions in real samples but also offers the advantages of rapid analysis, uncomplicated pretreatment procedures, environmental friendliness, and economical operation. This performance indicates that the WO₃/C modified gold electrode is feasible as an alternative electrode for nitrite ion detection.

The use of intact photosynthetic organisms (e.g. microalgae or cyanobacteria) for biotechnological approaches is a promising avenue to extract sustainable energy from oxygenic photosynthesis. More particularly, exogenous quinones can act as electron shuttles to reroute part of the photosynthetic electron flow of living cells to an outer collecting electrode. This encouraging approach is however hampered by reported poisoning or side-effects of exogenous quinones on the cell bioenergetics. In order to contribute to understand those effects, we investigated the modes and sites of interaction of two model quinones (2,6-DCBQ and 2,6-DMBQ) with the respiratory and photosynthetic electron transfer chains of the green alga Chlamydomonas reinhardtii. By considering different analytical tools (chlorophyll a fluorescence, transient absorption spectrometry, O₂ consumption rate), the two exogenous quinones are shown to hamper the photosynthetic electron transfer from photosystem II (PSII) to the cytochrome b₆f and, at longer term, PSII damage. In addition, the investigated quinones initiate the suppression of mitochondrial respiration, illustrated by the decrease of O₂ consumption. This results in the diminution of the ATP exchanges between mitochondrion and chloroplast responsible for the generation of the proton motive force across the thylakoid in darkness, and in turn affects the performances of the CF1FO ATPase. For all those effects, 2,6-DCBQ was more effective than 2,6-DMBQ in agreement with its higher redox potential and partition coefficient values. This work provides a new framework for the study of biophotovoltaic devices using photosynthetic organisms and quinones as mediators and could be extended to find the best candidates combining efficient bioelectricity production and limited toxicity.

In this report, the effect of Co content on the electrochemical hydrogen storage reaction kinetic of MgAlTiCo_xNi (x = 1, 1.5 and 2) High Entropy Alloys (HEAs) as negative electrodes under basic (6 M KOH) and acidic (1 M H₂SO₄) electrolyte was studied. Empirical thermodynamic parameters were used to predict the formation of HEAs. The alloys were obtained after 8 h of high-energy ball-milling. The structural analysis showed the formation of a BCC structure and a reduction of the unit lattice with increasing Co content. At high temperatures, the structure changes from BCC-type to B2-type. The morphology and surface area of the MgAlTiCoNi, MgAlTiCo_1.5Ni, and MgAlTiCo₂Ni alloy powders are very similar. Electrochemical measurements show that alloys exposed to acidic solutions as negative electrodes exhibit higher discharge capacity and better electrochemical hydrogen storage kinetics properties. The increase in Co content in the alloys in both basic and acidic solutions reduced the discharge capacity. Furthermore, a high Co content in the electrodes exposed to an acidic electrolyte reduces the anticorrosion properties of the alloy. The MgAlTiCoNi HEA electrode achieved the best electrochemical performance with a discharge capacity of 465 mAh/g in an acidic electrolyte after a short galvanic charge (60 min). The concentration of Co in the HEAs revealed a direct relationship with the hydrogen diffusion rate, while the lattice parameter is associated with the discharge capacity.

The microbiologically influenced corrosion (MIC) of X80 carbon steel under varying tensile stresses with the presence of sulfate reducing bacteria (SRB) was investigated. The stress loads affected the SRB sessile cell counts on the carbon steel, and exerted a significant influence on the rate of MIC to which the carbon steel was subjected. Stresses below 400 MPa elicited a modest promotion effect, whereas the stress of 550 MPa which was approaching the yield strength markedly expedited the corrosion of SRB on X80 carbon steel. Finite element simulation revealed that the elastic stress of 550 MPa led to plastic deformation in the stress concentration zone at the base of the corrosion pit, exacerbating the dissolution of the metal in pits and inducing secondary pitting corrosion. Additionally, this work confirmed that SRB promoted the permeation of hydrogen into the carbon steel matrix. The coexistence of high elastic stress and SRB rendered X80 carbon steel more prone to brittle fracture.

High-temperature Li-ion batteries capable of operating up to 100 ℃ can replace lithium thionyl chloride primary batteries in specialized industrial applications. Room-temperature ionic liquids (RTIL) offer high thermal stability and can be a promising choice of electrolyte for high-temperature batteries. This work elucidates that high thermal stability alone does not guarantee effective battery operation due to the electrochemical instability observed in RTIL-LiTFSI mixtures at elevated temperatures. Here, we investigate the impact of varying electrochemical stability in RTILs on half-cell, full-cell, and calendar aging. Electrochemical instability of the electrolyte at the cathode interface injects additional electrons and Li-ions into the electrochemical cell, triggering a cascade of detrimental chain reactions that hinder efficient battery performance. We demonstrate that electrochemical information gathered from a full-cell configuration can frequently obscure the presence of electrochemical instability at the cathode surface. To accurately evaluate this instability, it is essential to perform in-depth half-cell studies and other characterizations. Our results indicate that cathode electrolyte interphase (CEI) can reach a thickness of up to 100 nm, with a depth-dependent composition showing higher concentration of inorganic species like LiF and LiNSO near the cathode surface. Further, accelerated calendar aging measurements of such cells at high temperature revealed complete irreversible self-discharge within as little as 14 days. These findings shed light on the critical factors influencing the stability and performance of cells under challenging operating conditions.