Search Results (6,081)

A series of metal–organic framework-based materials of the MIL-101 family was prepared for potential application as anodic electrocatalysts in the direct borohydride fuel cell. The MIL-101-based materials were tested for borohydride oxidation reaction using cyclic voltammetry and chronoamperometry in alkaline media, with Au@MIL-101-NH₂ showing high responsiveness. The obtained data allow for the determination of kinetic parameters that characterize the borohydride oxidation on the prepared electrocatalysts. The activation energy for borohydride oxidation using an Au@MIL-101-NH₂ electrocatalyst was as low as 13.6 kJ mol⁻¹ with a reaction order of 0.4. The anodic charge transfer coefficient was 0.85, and the number of transferred electrons was 7.97, matching the theoretical maximum value of 8 electrons transferred during the borohydride oxidation reaction. The promising performance of Au@MIL-101-NH₂ suggests its potential application as an anode for direct borohydride fuel cells. Full article

Surface modification of carbon fibers (CFs) is a critical step in preparing carbon fiber-reinforced composites. This study developed a continuous experimental process that integrates electrochemical anodic oxidation and chemical vapor deposition to fabricate carbon nanotubes/carbon fiber (CNTs/CF) reinforcements. The effects of temperature and hydrogen flow rate during CNT growth on the resulting reinforcements were systematically investigated. The surface morphology and mechanical properties of the modified materials were characterized using scanning electron microscopy, Raman spectroscopy, and single-fiber tensile testing. Employing an Fe_0.5Ni_0.5 bimetallic catalyst under optimized conditions (550 °C, H₂ flow rate: 0.45 mol/min, C₂H₂ flow rate: 0.30 mol/min), the resulting reinforcement exhibited an 8.7% increase in tensile strength compared to as-received CF. Full article

A longitudinal magnetic field provides a new method for regulating the plasma velocity, pressure field, and temperature field of the TIG welding arc. However, the mechanism of action of the longitudinal magnetic field remains poorly understood. In order to address this problem, this paper develops a numerical model based on continuum mechanics. The mechanism of how magnetic field strength affects temperature, pressure field, plasma velocity, and potential was investigated. The geometric shape, temperature, pressure, and plasma velocity of the TIG welding arc under different magnetic fields were predicted. The results indicate that as magnetic field strength increases, the arc shape is compressed under the influence of magnetic forces, with the degree of compression increasing with magnetic field strength; plasma velocity gradually increases from 74 m/s at 0 mT to 296 m/s at 150 mT, but the velocity along the arc’s central axis first decreases and then increases with increasing magnetic field strength. As the magnetic field strength increases, a negative pressure first appears near the cathode, then expands toward the cathode, and finally toward the anode. During the expansion of the negative pressure, the maximum absolute value of the arc pressure increases by 12.72 times. Full article

This study demonstrates the feasibility of exciting NV centers using ITO-anode OLED devices, followed by the fabrication of GO/PEDOT:PSS hybrid anodes via spin-coating. Through interfacial modification, the OLED devices exhibit significantly enhanced luminescence intensity, leading to improved NV center excitation efficiency. Experimental results show that the optimized GO/PEDOT:PSS (40%) hybrid anode device achieves a lower turn-on voltage, with the NV center fluorescence peak intensity reaching 3.7 times that of the ITO-anode device, confirming the enhanced excitation effect through interfacial engineering of the light source. By integrating NV centers with OLED technology, this work establishes a new approach for efficient excitation. This integration approach provides a new pathway for applications such as quantum sensing. Full article

In this study, the catalytic air oxidation method was used to selectively form sodium antimonate from an antimony residue Na₂S-NaOH leaching solution of a high arsenic copper anode slime. In the first stage, the leaching process with Na₂S and NaOH media resulted in more than 98% leaching of antimony. The synergistic oxidation method was used to selectively separate antimony in the second stage. In this study, the oxidation rate of antimony was greater than 98% at the NaOH concentration of 50 g·L⁻¹ and a combined oxidation concentration of 0.75 g·L⁻¹ catechol + 0.75 g·L⁻¹ KMnO₄, under the air flow rates of 1.415 m³·min⁻¹ at 75 °C for 8 h. The pH of the crude sodium antimonate product was adjusted; subsequently, it was redissolved and precipitated to prepare refined sodium antimonate that meets the secondary product standard of China’s non-ferrous metal industry, which recommends an antimony recovery rate of >95.60%. After neutralisation, the liquid contains [As] < 0.10 g·L⁻¹, [Sb] = 0.16–0.38 g·L⁻¹, which can be reused in the composite leaching process. The apparent activation energy (Ea) of the catalytic oxidation reaction was 6.47 kJ·mol⁻¹; the results suggested that the reaction process was diffusion controlled. $-\frac{d\left[Sb\right]}{dt}=8.86\times {10}^{-5}\times e^{\frac{-778.44}{T}}\times {\left[Sb\right]}^{0.4906}\times {\left[NaOH\right]}^{1.190}$. Full article

This study investigated the effects of applied voltage on methane fermentation using separate reactors for the anode and cathode, with activated carbon felt as electrodes and a constant voltage of 0.7 V. Compared to the control, the cathode reactor exhibited approximately 1.2 times higher methane production and 1.3 times higher methane concentration, whereas the anode reactor showed a reduction to about 0.5 times and 0.8 times, respectively. Microbial analysis revealed that the anode reactor created an electron-accepting environment, promoting the growth of Clostridium sensu stricto 1 and Fastidiosipila, both contributing to organic acid (electron) production. Conversely, the cathode reactor established an electron-donating environment, enhancing methane production by hydrogenotrophic methanogens such as Methanoculleus and Methanobacterium. Although similar methanogen levels were found in the anode reactor, methane production was higher in the cathode reactor. These findings indicate that the anode facilitates organic acid production via electron acceptance, while the cathode acts as an electron donor that promotes hydrogenotrophic methanogenesis. This study provides a clear evaluation of the effects of microbial electrochemical technologies on methane fermentation, demonstrating their potential to stimulate microbial activities and enhance methane production. Full article

Graphene nanoshells (MGNS) were prepared from cellulose, a sustainable biopolymer. Different sizes/morphologies were obtained by simply changing the metal catalyst salt in the synthesis. The MGNS were shown to reversibly cycle Li-ions by an intercalation mechanism similar to graphite. The reversible capacity of each MGNS prepared from different metal salts correlates well to its degree of 3-D graphitic order. The small size of the MGNS allows for short Li diffusion distances and very rapid charging, obtaining a 20% charge in 36 s (100 C rate). The unique spherical structure provides stable cycling, losing only 3.8% capacity over 900 cycles, and eliminates exfoliation that occurs when cycling graphite in propylene carbonate (PC), an inexpensive, environmentally friendly electrolyte. This enables cycling in a PC-only solvent-based electrolyte, with stable cycling and high capacities at temperatures as low as −35 °C. At this very low temperature, 95% of the RT reversible capacity is retained, with only a modest charge potential increase due to the increase in viscosity of the solvent. Full article

This work examines the possibility of using a PbO₂-based electrode doped with the rare-earth metal holmium in the field of oxygen evolution and the development of an efficient method for the degradation of acetamiprid. Acetamiprid is a widely used insecticide and, as such, it very often reaches waterways, where it can cause many problems for wildlife and the environment. X-ray powder diffraction analysis, Raman spectroscopy, and energy-dispersive X-ray spectroscopy results confirmed the structure of Ti/SnO₂-Sb₂O₃/Ho-PbO₂, while the morphology of its surface was investigated by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Ti/SnO₂-Sb₂O₃/Ho-PbO₂ showed good OER activity in alkaline media with a Tafel slope of 138 mV dec⁻¹. The Ti/SnO₂-Sb₂O₃/Ho-PbO₂ electrode shows very good efficiency in removing acetamiprid. By optimizing the degradation procedure, the following operating conditions were obtained: a current density of 20 mA cm⁻², a pH value of the supporting electrolyte (sodium sulfate) of 2, and a concentration of the supporting electrolyte of 0.035 M. After optimization, the maximum efficiency of removing acetamiprid (10 mg L⁻¹, 4.5 × 10⁻⁵ mol) from water was achieved, 96.8%, after only 90 min of treatment, which represents an efficiency of 1.125 mol cm⁻² of the electrode. Additionally, it was shown that the degradation efficiency is strictly related to the concentration of the treated substance. Full article

Spatial navigation involves the use of external (allocentric) and internal (egocentric) processing. These processes interact differentially depending on age. In order to explore the effectiveness of these interactions in different age groups (study 1), we compared the performance of children and adults in a two-session spatial maze task. This task was performed under deprived vision, thus preventing visual cues critical for allocentric processing. Number of correct performances and performance time were recorded as outcome measures. We recruited thirty healthy participants for the children (mean age 10.97 ± 0.55) and the adult (mean age 21.16 ± 1.76) groups, respectively. The results revealed a significantly higher number of correct actions and shorter performance times during maze solving in children compared to adults. These differences between children and adults might be due to developmental and cortical reorganization factors influencing egocentric processing. Assuming that activation of the posterior parietal cortex (PPC) facilitates egocentric spatial processing, we applied excitatory anodal tDCS over the right PPC in a second study with a different healthy adult group (N = 30, mean age 21.23 ± 2.01). Using the same spatial navigation task as in study 1, we evaluated possible performance improvements in adults associated with this neuromodulation method. Compared to a sham stimulation group, anodal tDCS over the right PPC did not significantly improve spatial task performance. Full article

Metal–air batteries have excellent theoretical energy density and economic advantages through abundant anode materials and open cathode structures. However, the actual energy efficiency of metal–air batteries is much lower than the theoretical value due to the effect of polarization voltage during battery operation, limiting the power output and thus hindering their practical application. This review systematically dissects the origins of polarization: slow oxygen reduction/evolution reaction (ORR/OER) kinetics, interfacial resistance, and mass transfer bottlenecks. We highlight cutting-edge strategies to mitigate polarization, including atomic-level engineering of air cathodes (e.g., single-atom catalysts, low Pt catalysts), biomass-derived 3D porous electrodes, and electrolyte innovations (additives to inhibit corrosion, solid-state electrolytes to improve stability). In addition, breakthroughs in metal–H₂O₂ battery design using concentrated liquid oxygen sources are discussed. Together, these advances alleviate the battery polarization bottleneck and pave the way for practical applications of metal–air batteries in electric vehicles, drones, and deep-sea devices. Full article

The engineering of porous transport layer (PTL)–catalyst layer (CL) interfacial architecture plays a critical role in optimizing the performance of proton exchange membrane water electrolyzers (PEMWEs). Particularly, at the PTL-CL interface, our results reveal that anode catalyst loadings affect the modulation of the PTL surface structure on the overpotentials of PEMWEs. Under high anode catalyst loadings, the magnitude of overpotentials is predominantly governed by the electronic conductivity and mass transport resistance within the CL, where the modifying effects of PTL-CL interfacial contact characteristics become negligible. However, when the catalyst loading is reduced, the PTL-CL interfacial contact characteristics become critical for electron conduction, mass transport, and kinetic reaction. Under low catalyst loadings, the etched PTL demonstrates a maximum reduction of 59 mV compared to the pristine PTL at 4 A/cm², with the former exhibiting a 10 mΩ·cm² reduction. Meanwhile, the etched PTL integrated with a cell demonstrates superior performance in both mass transport and kinetic overpotentials compared to a pristine PTL. This clearly indicates that the surface structure of the PTL plays an increasingly significant role in regulating the overpotentials of PEMWEs as the catalyst loadings decrease. Full article

Photocatalytic water splitting for hydrogen production is an attractive renewable energy technology, but the oxygen evolution reaction (OER) at the anode is severely constrained by a high overpotential. The two-dimensional vdW ferromagnetic material Fe₃GeTe₂, with its good stability and excellent metallic conductivity, has potential as an electrocatalyst, but its sluggish surface catalytic reactivity limits its large-scale application. In this work, we adapted DFT calculations to introduce surface Te vacancies to boost OER performance of the Fe₃GeTe₂ (001) surface. Te vacancies induce the charge redistribution of active sites, optimizing the adsorption and desorption of oxygen-containing intermediates. Consequently, the overpotential of the rate-determining step in the OER process of Fe₃GeTe₂ is reduced to 0.34 V, bringing the performance close to that of the benchmark IrO₂ catalyst (0.56 V). Notably, the vacancies’ concentration and configuration significantly modify the electronic structure and thus influence OER activity. This study provides important theoretical evidence for defect engineering in OER catalysis and offers new design strategies for developing efficient and stable electrocatalysts for sustainable energy conversion. Full article

The MA₂Z₄ family represents a class of two-dimensional materials renowned for their outstanding mechanical properties and excellent environmental stability. By means of elemental substitution, we designed two novel phases of ScSi₂N₄, namely β₁ and β₂. Their dynamical, thermal, and mechanical stabilities were thoroughly verified through phonon dispersion analysis, ab initio molecular dynamics (AIMD) simulations, and calculations of mechanical parameters such as Young’s modulus and Poisson’s ratio. Electronic structure analysis using both PBE and HSE06 methods further revealed that both the β₁ and β₂ phases exhibit metallic behavior, highlighting their potential for battery-related applications. Based on these outstanding properties, the climbing image nudged elastic band (CI-NEB) method was employed to investigate the diffusion behavior of Li, Na, and K ions on the material surfaces. Both structures demonstrate extremely low diffusion energy barriers (Li: 0.38 eV, Na: 0.22 eV, K: 0.12 eV), indicating rapid ion migration—especially for K—and excellent rate performance. The lowest barrier for K ions (0.12 eV) suggests the fastest diffusion kinetics, making it particularly suitable for high-power potassium-ion batteries. The significantly lower barrier for Na ions (0.22 eV) compared with Li (0.38 eV) implies that both β₁ and β₂ phases may be more favorable for fast-charging/discharging sodium-ion battery applications. First-principles calculations were applied to determine the open-circuit voltage (OCV) of the battery materials. The β₂ phase exhibits a higher OCV in Li/Na systems, while the β₁ phase shows more prominent voltage for K. The results demonstrate that both phases possess high theoretical capacities and suitable OCVs. Full article

This work focused on the photocatalytic performance enhancement of titanium dioxide (TiO₂) nanotubes decorated by gold nanoparticles. The surface of the nanotubes synthesized using the anodization technique was modified with subsequent deposition of gold nanoparticles (Au-NPs) via electrophoretic deposition. The impact of electrophoretically deposited gold nanoparticles (Au-NPs) on TiO₂ nanotubes, with varying deposition times (5 min, 8 min and 12 min), was investigated in the degradation of amido black (AB) dye. The morphological analysis using scanning electron microscopy (SEM, TESCAN VEGA3, TESCAN Orsay Holding, Brno, Czech Republic) and transmission electron microscopy (TEM, JEM—100CX2, JEOL Japan). revealed a well-organized nanotubular structure of TiO₂, with a wall thickness of 25 nm and an internal diameter of 75 nm. Optical study, including photoluminescence and diffuse reflectance spectroscopy, provided evidence of charge transfer between the Au-NPs and the TiO₂-NTs. Furthermore, the photocatalytic measurements showed that the enhanced photocatalytic activity of the TiO₂-NTs resulted from successful Au deposition onto their surface, surpassing that of the pure sample. This improvement is attributed to the higher work function of gold nanoparticles, which effectively promoted the separation of photogenerated electron–hole pairs. The sample Au-NPs/TiO₂-NTs with a deposition time of 5 min exhibited the best photocatalytic efficiency, achieving an 85% degradation rate after 270 min under UV irradiation. Moreover, the enhancement obtained was also attributed to the plasmonic effect induced by Au-NPs. Kinetic investigations revealed that the photocatalytic reaction followed apparent first-order kinetics, highlighting the efficiency of Au-NPs/TiO₂-NTs as a photocatalyst for dye degradation. Full article

This study compares the Eddy current technique and optical microscopy for measuring the anodized layer thickness in a 6063 aluminum alloy with the aim of establishing an efficient and accurate methodology capable of delivering optimal results in a time-efficient manner. Optical microscopy was used as the reference method, with five measurements taken in different fields for each specimen. The Eddy current method was applied using two calibration strategies: one calibration before each measurement and another after every ten specimens. The Bland–Altman analysis was employed to compare both measurement techniques. The results indicated that the calibration before each measurement strategy using Eddy current showed higher agreement with the reference method, suggesting that both techniques can be considered equivalent and interchangeable. Furthermore, the Eddy current method demonstrated significant advantages in detecting thickness variations along the specimen, revealing non-uniform distribution of the anodized layer. This method also proved to be faster and eliminated the need for metallographic preparation required by optical microscopy, thus significantly reducing analysis time and cost. In conclusion, the Eddy current method with calibration before each measurement strategy is proposed as an effective alternative for measuring anodized layer thickness in applications where speed and precision are critical. Full article