<p>Various contaminants present in cathode air streams may significantly affect the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, sulfur dioxide (SO2) and nitrogen dioxide (NO2) were selected as representative airborne impurities to quantitatively investigate their individual and combined effects on PEMFC performance. Experiments were conducted using five different NO2:SO2 mixture ratios (100:0, 75:25, 50:50, 25:75, and 0:100), while maintaining a constant total contaminant concentration as 100 ppm. The results revealed a pronounced decline in cell performance with increasing NO2 proportion, whereas performance degradation progressed more gradually with higher SO2 concentrations. Cyclic voltammetry (CV) analysis showed that SO2 exhibited strong and persistent adsorption on the platinum catalyst surface, which was not fully removed even after exposure to neat air during the recovery process. These findings were further supported by electrochemical impedance spectroscopy (EIS), indicating that SO2 contamination caused sustained increases in charge transfer resistance and a notable decrease in electrochemical active surface area. In contrast, NO2-contaminated systems exhibited comparatively faster performance recovery. This paper provides valuable insights into the degradation and recovery behaviors of PEMFCs under mixed-gas contamination, contributing to the development of effective mitigation strategies for improving fuel cell durability in polluted environments.</p>

<p>Electrochemical nitrogen reduction reaction (eNRR) is a promising sustainable alternative to the energy-intensive Haber–Bosch process for ammonia (NH₃) synthesis. However, simultaneously achieving high activity and selectivity remains challenging due to competing hydrogen evolution reaction (HER). In this study, a series of copper sulfide catalysts were investigated for eNRR under ambient conditions. Copper sulfides featuring highly crystalline low-index (1 1 1) facets exhibited significant NH₃ production; however, the presence of high-index facets led to a reduction in Faradaic efficiency (F.E.) due to their higher activity toward the competing HER. To mitigate this intrinsic trade-off between activity and selectivity, bromide ions were introduced to selectively adsorb onto the high-index planes, effectively suppressing HER. Optimizing the bromide ion coverage on CuSₓ catalysts resulted in a maximum NH3 yield of 1.2 μmol h–¹ cm–² (JNH3 = 0.198 mA/cm2) and a F.E. of 23.34% at −0.6 VRHE, marking improvements of 84.0% in activity and 316% in selectivity compared to untreated catalysts. It was verified that bromide ions selectively passivate HER-prone surfaces without blocking the active sites responsible for nitrogen adsorption. This study highlights that facet-selective surface engineering using halide ions can simultaneously enhance both activity and selectivity in eNRR. It provides a rational design principle for improving catalytic performance in complex reaction environments where multiple pathways compete.</p>

<p>The solubility of tetraethylammonium tetrafluoroborate (TEA BF4) in acetonitrile (AN) is approximately 1.65 M. Solutions ranging from 0.3 to 1.5 M were prepared to investigate the effect of concentration on performance and cycle life of electrochemical double-layer capacitors. The time constant indicates that the rate capability improves with increasing concentration. Higher concentrations result in higher energy densities at the highest power densities. Accelerated durability tests and electrolysis current on the positive electrodes revealed that AN degraded more readily than salt in the electrolyte during cycling. Therefore, higher concentrations, such as 1.2 and 1.5 M, are advantageous for prolonged cycling and high-temperature conditions. The significant degradation of AN and the binder on the positive electrode increases cell resistance, thereby reducing cycle life. Concentrations closer to the solubility limit of the salt were more favorable for increasing the energy density and cycle life compared with lower concentrations. However, concentrations close to solubility make ionic movement very sluggish at low temperatures, which limits use because their performance deteriorates rapidly at low temperatures.</p>

The metals and metal compounds used to construct nitrite sensors dissolve into the solution during operation due to reactions, which not only pollutes the environment but also affects the long-term stability of the sensor. Hence, This study developed a stable and sensitive non-metallic based nitrite electrochemical sensor by directly growing carbon dots(CDs) in situ on carbon cloth(CC) using citric acid and ethylenediamine as precursors. The growth of CDs on CC was confirmed through inverted fluorescence microscopy, transmission electron microscope, and X-ray photoelectron spectrometer. The CDs/CC electrode material, rich in hydrophilic functional groups, enhances contact between the electrode and electrolyte, significantly improving electrical conductivity, active specific surface area and the quantity of active sites on the electrode material. The electrochemical performance results showed that the synergistic effects between the CDs and CC significantly enhanced the electrocatalytic activity toward nitrite. Nitrite detection was achieved high sensitivity, with a detection limit of 0.14 μM. The sensor's performance was further validated by analyzing nitrite in ham sausage, achieving recoveries between 97.72% and 101.40%. This study proposes a new method for manufacturing flexible electrochemical sensors that respond to different target objects by growing different carbon dots on carbon cloth.

We utilized a Back Propagation (BP) neural network combined with a Genetic Algorithm (GA) to optimize the parameters of the Watts nickel plating process, aiming to enhance the coating hardness. The BP neural network model used current density, pH value, boric acid concentration, and bath temperature as input parameters, while coating hardness was the output. The introduction of quadratic polynomial features allowed the model to achieve a coefficient of determination (R2) of 0.973. After GA optimization, the optimal parameter combination was identified as: current density of 1.3 A dm–2, pH value of 3.6, boric acid concentration of 20.5 g·L–1, and plating bath temperature of 42.3℃. The results reveal that orientation and grain size significantly affect the microhardness of nickel coatings. Specifically, the (220) crystal plane most strongly influences hardness, followed by the (111) crystal plane, while the (200) crystal plane has the least effect. By optimizing the electroplating process parameters, it is possible to control the crystal orientation of the coating, thereby affecting the hardness of the coatings. There is a negative correlation between grain size and the hardness. Additionally, In Watts nickel plating, the current density, pH value, boric acid concentration, and bath temperature jointly affect the mechanical properties of the coatings, their synergistic action determines the coating quality. We demonstrate that combining GA with neural networks is an effective method for optimizing the deposition parameters and solution chemistry of Watts nickel plating and improving the quality of the coatings.

<p>Although lithium-metal batteries (LMBs) have attracted significant attention as advanced energy storage systems, the rapid growth of dendritic Li causes drastic thermal runaway because it is hard to control the growth of dendritic Li using conventional polyethylene (PE) separators. This study aims to develop dendrite-suppressible PE separators by incorporating waste oyster shells (OS). Although OS are considered marine wastes, they have a high shear modulus that can suppress Li dendrite growth, suggesting that incorporating OS into the PE separator would improve the mechanical properties of the PE separator. The OS are embedded onto the PE separator by the blade-casting method, and analysis of the thermal and electrochemical behaviors indicates that the OS-incorporated PE separator is compatible with the Li metal anode. Consequently, the OS-incorporated PE separator exhibits stable cycling behavior in the Li||Li symmetric cell, in addition to the Li||LiMn<sub>0.6</sub>Fe<sub>0.4</sub>PO<sub>4</sub> (LMFP64), compared to that cycled with unmodified PE.</p>

<p>For the safe and efficient operation of electric vehicles, health monitoring and the prognosis of their battery systems are essential. The level of complexity in diagnostic and prognostic tools is increasing in tandem with the continuous evolution of technologies in Electric Vehicles (EV). Effective battery diagnostics help improve the longevity and performance of EV batteries and achieve environmental and economic benefits. Direct measurement of battery voltage, current, impedance, and temperature, electrochemical techniques like cyclic voltammetry and impedance spectroscopy, data-driven and model-based approaches are the different tools available for diagnosis and prognosis of EV batteries. Electrochemical Impedance Spectroscopy (EIS) is a robust, non-invasive, and non-destructive electrochemical technique used to characterize and model electrochemical systems, by measuring their impedance spectrum. EIS is a widely used technique with applications in the study of corrosion, paint, sensors, biosensors, batteries, fuel cells, etc. It is a powerful diagnostic and prognostic tool for battery systems to carry out functions like failure prediction, thermal management, fault detection etc. This review focuses on the implementation of EIS technique in various EV battery applications, highlighting both the unique advantages and challenges faced in its implementation.</p>

<p>Previous researches have shown that the modification of the flow channel structure in PEMFC significantly impact reactant distribution and the overall performance of the fuel cell. During this research, the biomimetic leaf veininspired flow channel (BIFC), inspired by Ginkgo biloba leaf veins, was designed to optimize electrochemical reactions in PEMFC. Different number and arrangement of refinement channels between tributary channels based on various configurations of BIFC using three-dimensional numerical simulations with COMSOL Multiphysics. BIFC-6, with staggered arrangement of three refinement channel tiers, surpassed traditional approaches, showing low pressure drops, consistent distribution of reactants, and increased power output. Notably, BI-6 achieved the peak power density of 0.58 W/cm<sup>2</sup>, 38.8% higher than that of CPFC and 9.4% higher than that of the original bionic flow channel. The research was also aimed at refining the width of the channel and comparing the output performance of the fuel cell with different widths. The results showed that Type-5 achieved the peak power density of 0.612W/cm<sup>2</sup>, which was 15.5% improvement compared with BI-0. These findings highlight the impact of rationally designing refined flow channels to enhance fuel cell output performance.</p>

Zn metal is one of the highest capacity anodes for aqueous rechargeable batteries. However, the serious issue of dendrite growth during Zn plating/stripping must be addressed on Zn metal electrode. Sculpting three-dimensional nanostructure patterns on the Zn anode surface is a method to achieve high stability and reversibility. We demonstrate the surface modification of Zn metal foil into a well-arranged V-shaped valley-like Zn nanoarray surface using the laminar flow of an etchant solution, based on a mechanism that mimics the formation of valleys in nature. The improved accessible surface area reduces the local current density, resulting in uniform Zn nucleation, thereby inhibiting dendrite growth. The surface alternation was also found to unveil crystallographic orientations that promote planar growth, further limiting dendrite growth. Such surface-modified Zn anodes demonstrate excellent reversibility, with a 4-fold increase in cycle-life compared to bare Zn. A full cell with a V2O5 cathode and a surface-modified Zn anode delivered a capacity of 175 mAh g–1 and retained 80 percent of its capacity after >500 cycles, compared to only 30% with an unmodified Zn anode. Overall, this work highlights a method to improve the reversibility of ZIBs through surface modification of the Zn anode.