ChemElectroChem最新文献

Disordered carbon is the state of the art anode material for Na-ion batteries due to their increased interlayer spacing and good electronic conductivity. However, its practical application is hindered by average specific capacity, poor rate performance, low coulombic efficiency and limited cycling stability. Herein, we report the superior pseudocapacitance enhanced Na-ion storage of in situ surface functionalized carbon nanosheets. Anodes composed of ultrathin (~15 nm) carbon nanosheets demonstrated excellent reversible specific capacity (375 mAh/g at 25 mA/g), rate performance (150 mAh/g at 2 A/g), long-term cycling performance (1000 cycles at 1 A/g) and coulombic efficiency (~100 %). Considerably higher pseudocapacitance (up to ~78 %) is also identified in this case compared to amorphous carbon particles. Spectroscopic and electrochemical studies proved Na-ion intercalation in to the disordered carbon and pseudocapacitive storage driven by oxygen-containing surface functional groups. Outstanding electrochemical performance is credited to the synergy between diffusion limited intercalation and pseudocapacitive surface Na-ion storage. The demonstrated synthetic method of in situ functionalized carbon nanosheets is inexpensive and scalable. The strategy of functional group and morphology induced pseudocapacitive Na-ion storage offer new prospects to design high-performance Na-ion battery electrodes.

Aluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium-ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α-phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al-based batteries. The native passivation layer, Al₂O₃, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β-LiAl is found to be 40.5 kJ mol⁻¹, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol⁻¹). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium-ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones.

The integration of flexible micro- and nanodevices plays a pivotal role in investigating stress-enhanced performances and underlying intrinsic mechanisms for two-dimensional materials. This study presents the fabrication of single-crystal flexible devices using monolayer MoS₂ and its catalytic activities for the hydrogen evolution reaction under stress conditions. A metallic conductive layer was deposited on the photoresist surface via magnetron sputtering, overcoming the challenges associated with lithography on insulating substrates using electron beam lithography (EBL). The results demonstrate optimal etch patterns with a metal modification layer thickness of 10.97 nm. Leveraging this flexible device fabrication process, a single-layer MoS₂ single-nanosheet flexible micro/nano device was developed and subsequently strain-modulated (stretched along the zigzag lattice direction with the armchair lattice direction as the axis). A significant enhancement is observed in the electrocatalytic hydrogen evolution performance as the strain increases from 0 % to 0.40 %. Notably, the onset overpotential decreased from 155.6 to 95.7 mV, and the Tafel slope decreased from 175.3 to 98.6 mV dec⁻¹. This study provides new insights into the design and performance of strain devices for two-dimensional (2D) monocrystalline/polycrystalline materials.

The relentless quest for sustainable and efficient energy storage solutions has propelled sodium-ion batteries (SIBs) to the forefront of research and development in the realm of rechargeable batteries. This mini review delves into the intricate interfacial kinetics of Na ion transfer within SIBs, with a special focus on the carbon-based negative electrode/electrolyte interfaces. By synthesizing insights from a myriad of studies encompassing experimental and theoretical analyses, we illuminate the critical role of electrode material properties and interfacial dynamics in dictating the kinetics of Na ion transfer for SIBs. Strategies for optimizing these parameters are scrutinized, revealing pathways to enhance the kinetic behavior of Na ions. Furthermore, emerging materials such as hard carbon, carbon nanospheres, and graphene-like graphite are evaluated for their potential to surmount existing limitations.

Gamma-aminobutyric acid (GABA) is involved in the signal transduction and metabolism of various substances in plants. Its in vivo detection in plants is of great importance for understanding its physiological role. In this study, an ultrasensitive electrochemical immunosensor is developed for in vivo detecting GABA in plants based on screen printed electrode (SPE) electrode. Gold nanoparticles (Au NP) was electrodeposited on the SPE to improve the conductivity of the electrode. Nanocomposite of ferrocene-Carboxylated graphene oxide-carboxylated multi-walled carbon nanotubes (Fc-GO-MWCNT) was fabricated on the electrode to improve the electrochemical properties of the sensor, and Fc was used to generate electrochemical signals. Then polydopamine (PDA) was electropolymerized on the electrode to improve the electrochemical activity of the sensor and increase the loading amount of GABA antibody. The as-prepared immunosensor shows the widest detection range of 10 fM to 10 mM, and lowest detection limit of 1.9 fM (S/N=3) for GABA. This immunosensor was applied for in vivo detecting GABA in the cucumber leaves under salt stress. Our sensor is the first electrochemical immunosensor for in vivo detecting GABA in plant. It proposes a new strategy for the development of immunosensor for in vivo detection of biomolecules in plants.

The concept of nanostructuring and doping of hematite (α-Fe₂O₃) photoanodes have been widely engaged towards improving their photoelectrocatalytic (PEC) response. Here, a FeCl₃-based solution was modified with 0–10 % polyethylene glycol (PEG) 400 and used as an electrolyte for the electrodeposition of nanostructured α-Fe₂O₃ thin films. The electrolyte containing 10 % PEG was further used to prepare Mn-doped α-Fe₂O₃ films by adding 1, 3, 6, and 10 % of MnCl₂.4H₂O with respect to the molarity of FeCl₃. The addition of 10 % PEG into the electrolyte limited particle agglomeration and yielded the best PEC response among the pristine films. The 3 % Mn-doped α-Fe₂O₃ photoanodes produced the highest photocurrent, yielding 2.2 and 6.1-fold photocurrent enhancement at 1.23 V and 1.5 V vs. RHE respectively, over the pristine films. The improved PEC response is linked to the reduced particle agglomeration and improved charge transport properties observed for the films. Density functional theory (DFT) calculations of the formation energies yielded negative values for the Mn-doped α-Fe₂O₃, which implies that the materials are thermodynamically stable after doping. This work introduces a new pathway for the electrodeposition of doped α-Fe₂O₃ films and underscores the roles of Mn-doping in boosting their PEC response.

Lithium (Li) metal is a promising candidate for next-generation high-energy-density rechargeable batteries. However, the solid electrolyte interphase (SEI) inevitably suffers from mechanical fracture owing to the large morphological change during Li cycling, leading to the uncontrollable growth of Li dendrites, low Coulombic efficiency, and short cycle life. The fabrication of an artificial interphase is an effective strategy for improving the performances of Li metal anodes. The ideal artificial interphase should provide sufficient mechanical robustness to suppress dendritic Li growth and accommodate large volume changes during Li deposition-dissolution cycles. In this review, we focus on the fabrication of mechanically robust artificial interphases for stabilizing Li-metal anodes, including the underlying mechanism of SEI fracture, quantitative requirements for mechanical properties, measurements of mechanical properties, and recent progress in the fabrication of mechanically stable artificial interphases.

This study reports the photoelectrocatalytic (PEC) activity of a n–n heterojunction comprising MoS₂ and NiSe₂. The synthesis of the composite was achieved through a facile solvothermal method, yielding an exfoliated MoS₂ layered sheet loaded with NiSe₂ nanoparticles. Under visible light radiation and an external electric field, the obtained composite NiSe₂/MoS₂ exhibited enhanced catalytic activity for ciprofloxacin (CIP) degradation. The NiSe₂/MoS₂ heterojunction achieved about 78 % degradation efficiency with a first-order kinetic rate of 0.0111 min⁻¹, compared to 38 % efficiency and a first-order kinetic rate of 0.0044 min⁻¹ observed for MoS₂. The NiSe₂/MoS₂ heterojunction was more advantageous due to the synergy of charge carrier induction by visible light radiation and improved charge carrier separation induced by the external electric field. The formation of n–n heterojunction at the interface of the two materials resulted in charge redistribution in the materials, with a simultaneous realignment of the band structure to achieve Fermi energy equilibration. The primary reactive species responsible for CIP degradation was identified as the photo-induced h⁺. Furthermore, the catalyst exhibited high stability and reusability, with no significant reduction in activity observed after five experimental cycles. This study reveals the potential of exploring the synergy between the photocatalytic and electrocatalytic processes in removing harmful pharmaceutical compounds from water.

This study highlights for the first-time the utilization of nickel foam coated with activated carbon (AC) via the electrophoretic deposition (EPD) method in the fabrication of A7 sized pouch cell supercapacitors. The scale-up of electrodes via EPD from coin to pouch cells with mass loadings (10 mg cm⁻²) and thicknesses (>130 μm) that match industrial standards is also reported. Research investigations include: (a) comparison of a two dimensional (2D) aluminum foil current collector's performance with three dimensional (3D) microporous nickel foam current collectors, (b) impact of EPD of AC onto small (10 cm²) and large areas (50 cm²) of nickel foam, and (c) scaling-up of coin to pouch cells along with a comparison against electrodes prepared via the standard doctor blade coating (or slurry casting) method. We demonstrate practical cell performance, including specific current loading (40 A g⁻¹), hundred thousand of successive charge and discharge operation (150,000 cycles), power (27 kW kg⁻¹) and energy densities (37.7 W h kg⁻¹), capacitance (174 F g⁻¹), capacitance retention (80 %) and coulombic efficiency (close to 100 %).

Modifying the chemical environment of active surfaces with ionic liquids (IL) is an emerging strategy for tailoring novel electrocatalytic systems, including carbon dioxide reduction (CO₂RR). Although copper (Cu) catalysts have recently gained more attention in this field, their modification with ILs is yet to be investigated. This work tested a range of common hydrophobic ILs impregnated into carbon-supported Cu catalysts, following the “solid catalyst with ionic liquid layer” (SCILL) approach. The latter was used to showcase the applicability of real-time product detection for CO₂RR employing electrochemical mass spectrometry. The observed patterns of C₁ to C₃ product selectivity offered valuable insights into the intricate reaction mechanism. In addition, increasing the size of the IL cation showed an opposite and significant effect on the reaction selectivity. The obtained qualitative results were partially compared with conventional long-term experiments.