Search Results (6,111)

Antioxidants, such as flavonoids, are influential secondary metabolites that play a significant role in regulating human health. Açaí, known for its potent antioxidant properties, has gained popularity in the nutritional field. However, there is a need for accurate methods to quantify its antioxidant capacity. Therefore, the goal of this investigation was to determine the total antioxidant capacity of frozen açaí pulp by applying the concept of the electrochemical quantitative index (EQI) using the cyclic voltammetry technique. The electrochemical response of ethanolic extracts obtained by a nonconventional ultrasound bath was investigated in the anodic region. The results clearly showed redox behavior at +0.37 V and +0.27 V (vs. Ag/AgCl) for the anodic and cathodic peaks, respectively, when evaluated by cyclic voltammetry at a glassy carbon (GC) electrode. By investigating a constant ethanolic extract concentration (0.2%) and analyzing the scan rate and supporting electrolyte effects, it was determined that the frozen açaí pulp extract presented an EQI of about 2.3 µA/V. Similarly, the concept of the EQI was extended to the use of the differential pulse voltammetry profile of a 0.2% ethanolic açaí extract on different supporting electrolytes, which showed that some experimental conditions needed improvement. Still, maintaining pH with a buffer solution in the anodic region is crucial to ensure reproducibility. The antioxidant capacity was also determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay to compare the electrochemical results. The Folin–Ciocalteu colorimetric test was applied to determine the total phenolic content of the extract. Full article

Biomass resources are excellent candidates for carbon electrode materials due to their abundance, renewability, and biodegradability. Herein, the solanaceous crop Tobacco Straw, a rich agricultural by-product, was utilized to prepare biomass-derived carbon material (TsC) and applied as an anode in lithium-ion batteries (LIBs). Doping or composite formation is considered to enhance the electrochemical performance. Doping extra nitrogen (N) atoms into the TsC (denoted as TsNC) demonstrated exceptional reversible specific capacity (475.9 mA h g⁻¹ at the current density of 60 mA g⁻¹ after 500 cycles) and remarkable long-term cycling stability (142.9 mA h g⁻¹ even at a high current density of 1.5 A g⁻¹ after 1000 cycles, much larger than that of TsC), attributed to the increased lithium-ion (Li-ion) adsorption sites including graphitic-N, pyrrolic-N, and pyridinic-N. Furthermore, kinetic analysis revealed that a prominent predominant surface capacitive-controlled behavior was responsible for the superior rate performance of TsNC, which could facilitate rapid charging and discharging at high rates. This work offers valuable insights into the application and modification of nitrogen-doped biomass-derived carbons with outstanding electrochemical properties for LIBs. The strategy also sheds light on enabling waste recycling and generating economic benefits. Full article

Among various H₂ production methods, splitting water using renewable electricity for H₂ production is regarded as a promising approach due to its high efficiency and zero carbon emissions. The oxygen evolution reaction (OER) is an important part of splitting water, but also the main bottleneck. The anodic oxygen evolution reaction (OER) for water electrolysis technology involves multi-electron/proton transfer and has sluggish reaction kinetics, which is the key obstacle to the overall efficiency of electrolyzing water. Therefore, it is necessary to develop highly efficient and cheap OER electrocatalysts to drive overall water splitting. Herein, a series of efficient RuO₂-Co₃O₄ composites were synthesized via a straightforward three-step process comprising solvothermal synthesis, ion exchange, and calcination. The results indicate that using 10 mg of RuCl₃·xH₂O and 15 mg of Co-MOF precursor in the second ion exchange step is the most effective way to acquire the Co₃O₄-RuO₂-10 (RCO-10) composite with the largest specific area and the best electrocatalytic performance after the calcination process. The optimal Co₃O₄-RuO₂-10 composite powder catalyst displays low overpotential (η₁₀ = 272 mV), a small Tafel slope (64.64 mV dec⁻¹), and good electrochemical stability in alkaline electrolyte; the overall performance of Co₃O₄-RuO₂-10 surpasses that of many related cobalt-based oxide catalysts. Furthermore, through integration with a carbon cloth substrate, Co₃O₄-RuO₂-10/CC can be directly used as a self-supporting electrode with high stability. This work presents a straightforward method to design Co₃O₄-RuO₂ composite array catalysts for high-performance electrocatalytic OER performance. Full article

The surface treatments and various magnesium alloys are applied to improve the fast degradation rate and resulting negative effects of magnesium alloys. This study aimed to assess the effect of anodic oxidation treatment of magnesium–calcium (Mg-Ca) systems by creating artificial bone defects in the tibia of rats. The cylinder magnesium implants were fabricated using a Mg-xCa (x = 0, 1, 5 wt.%) binary alloy. Degradability and new bone formation were observed at two and six weeks using micro-CT. Histomorphometric parameters were evaluated with Goldner’s trichrome staining. The degradation rate decreased depending on the amount of calcium added. The parameters related to bone formation revealed an increasing pattern depending on the addition of calcium, anodic oxidation, and time. The amount of absorbed magnesium to assess degradability of magnesium implants by the histomorphometric analysis revealed a high value in the untreated group at two and six weeks. Bone healing parameters increased depending on the amount of calcium added, anodic oxidation treatment, and region of interest (ROI—0.5 mm, 1.00 mm, 1.5 mm, and 2.0 mm). Biodegradable magnesium systems have the potential to replace bone screws and plates. Combination with calcium combined with anodization surface treatment can improve initial corrosion resistance and promote bone formation. Full article

The upcycling of spent lithium-ion battery graphite constitutes an essential pathway for mitigating manufacturing expenditures and alleviating ecological burdens. This study proposes an integrated strategy to upcycle spent graphite into high-performance porous expanded graphite (PEG) anodes, leveraging flash Joule heating (FJH) as a core technique for efficient decontamination, interlayer expansion, and active etching. Results show that the binders and impurities are efficiently removed by FJH treatment, and the graphite interlayer spacing is expanded. The iron oxide, which acts as an etching reagent, can then be easily intercalated and laid into the decontaminated graphite for subsequent etching. A subsequent FJH treatment simultaneously releases oxidized intercalants and triggers in-situ metal oxide etching, yielding PEG with a rich porous architecture and enhanced specific surface area. This method successfully prepared high-performance porous expanded graphite anode material with a mesoporous structure. The resulting anode delivers a remarkable capacity retention of 419 mAh·g⁻¹ after 600 cycles at 2C, outperforming the performance of commercial graphite anodes. This innovative approach offers a promising route for sustainable graphite reclamation. Full article

This research introduces a synergistic photoelectrocatalytic (PEC) system designed for the effective degradation of tetracycline (TC), integrating a PO₄³⁻-grafted Mo-doped BiVO₄ (PO₄³⁻-Mo:BiVO₄) photoanode with a Pd-loaded ordered mesoporous carbon (Pd/CMK-3) cathode. The incorporation of Mo doping and PO₄³⁻ modification significantly improved the photoanode’s charge separation efficiency, achieving a photocurrent density of 2.9 mA cm⁻², and fine-tuned its band structure to enhance hydroxyl radical (·OH) generation. Meanwhile, the Pd/CMK-3 cathode promoted a two-electron oxygen reduction reaction pathway, producing hydrogen peroxide (H₂O₂) and facilitating molecular oxygen activation via atomic hydrogen (H*) intermediates. Under optimized conditions—1.0 V vs. Ag/AgCl of anodic potential, pH 6.58, and oxygen saturation—the combined system accomplished 80% TC degradation within 60 min, markedly surpassing the performance of the photoanode (72%) or cathode (71%) alone. Notably, this synergistic approach also reduced energy consumption to 0.0065 kWh m⁻³, outperforming individual components. Radical quenching experiments and liquid chromatography–mass spectrometry (LC-MS) analysis revealed that the photogenerated holes (h⁺) and ·OH were the key reactive species responsible for TC mineralization. The system demonstrated remarkable stability, with only a 2.96% decline in activity, and effectively degraded other contaminants, such as phenol, 4-chlorophenol, and ciprofloxacin. This study highlights an energy-efficient PEC strategy that harnesses the combined strengths of anodic oxidation and cathodic molecular oxygen activation to significantly enhance the removal of organic pollutants. Full article

Current electrolytic refining processes for crude solder commonly employ fluosilicic acid (H₂SiF₆) as the electrolyte with bone glue and β-naphthol additives yet suffer from poor electrolyte stability, coarse cathode crystallization, low current efficiency, and high energy consumption, adversely affecting product quality and economic viability. In order to solve these limitations, electrochemical techniques, XRD, SEM, and ICP-OES were used to study the effects of gelatin and sodium lignosulfonate on the deposition overpotential and cathode morphology, as well as the effects of process parameters on current efficiency and energy consumption. A novel approach was developed using an H₂SiF₆ system enhanced by gelatin and sodium lignosulfonate for crude solder refining. After optimization, 120 h electrolysis achieved a current efficiency >97.8%, smooth/dense cathode surface, average cell voltage of 0.24 V, and energy consumption of 98.15 kWh/t. Efficient deposition of 81.2% Sn and 75.2% Pb on the cathode was realized, while >93.3% of Sb, Bi, Ag, Cu, and As were enriched in anode slime to facilitate valuable metal recovery, and >90.6% of In/Al concentrated in the electrolyte enabled effective Sn-Pb impurity separation. This study provides theoretical and technical foundations for advancing sustainable and economical electrolytic refining of crude solder. Full article

To develop a CO₂-free process for recovering Fe and Zn metals from electric arc furnace (EAF) dust, this study investigated the molten oxide electrolysis of various Fe₂O₃–ZnO mixtures in a B₂O₃–Na₂O electrolyte. Electrolysis was conducted using an Fe cathode and Pt anode at 1173 K by applying cell voltages that were determined based on thermodynamic calculations and cyclic voltammetry measurements. When electrolysis was conducted at a cell voltage of 1.1 V, the selective reduction of Fe oxide to Fe metal was observed without ZnO reduction. However, when 1.6 V was applied, the co-reduction of Fe oxide and ZnO to the Fe–Zn alloy was observed. In the vacuum distillation of the Fe–Zn alloy at 1000–1200 K, Zn metal with a purity of ≥99.996% was obtained with a recovery efficiency of ≥99.9%, under certain conditions. This study demonstrates the feasibility of recovering Fe and Zn from EAF dust using low-temperature molten oxide electrolysis and subsequent vacuum distillation. Full article

High-strength galvanized parallel steel wire (HSGPSW) is a primary load-bearing component in cable-supported bridge structures. However, due to both human and environmental factors, corrosion during its service life is often inevitable, and in severe cases, it may threaten the structural safety of the bridge. In this study, a novel method employing the organic corrosion inhibitor hydroxyethylidene diphosphonic acid (HEDP) is proposed to mitigate the corrosion of HSGPSW. First, electrochemical accelerated corrosion tests were conducted on 48 specimens immersed in HEDP solutions to investigate the effects of three key parameters—HEDP concentration, tensile stress, and inhibition duration—on the mass loss rate of the specimens. Subsequently, tensile tests were performed on the inhibited specimens to obtain their load–displacement curves, and the maximum tensile load under the influence of HEDP was comparatively analyzed. The results show that at an HEDP concentration of 0.12 mol·L⁻¹, the inhibition efficiency reached 40.31%, but it became saturated when the concentration exceeded 0.08 mol·L⁻¹. At a tensile stress of 7.5 kN, the inhibition efficiency decreased to 13.24%, with passive film breakdown identified as the primary cause of performance degradation. Energy-dispersive spectroscopy (EDS) analysis revealed that HEDP significantly stunts zinc layer dissolution, thereby enhancing initial corrosion protection, while mechanical tests indicated that its ability to slow the degradation of tensile performance diminishes after film rupture. The corrosion inhibition mechanism is attributed mainly to the synergistic effect of anodic suppression and interfacial coordination. This study provides a new method and novel insights for the corrosion protection of high-strength galvanized HSGPSW in cable-supported bridge structures. Full article

Glass, as an amorphous material with excellent optical transparency and chemical stability, plays an irreplaceable role in modern engineering and technology fields such as semiconductor manufacturing and micro-electro-mechanical systems (MEMS). For example, borosilicate glass, with a coefficient of thermal expansion (CTE) that is close to having good thermal shock resistance and chemical stability, can be applied to MEMS packaging and aerospace fields. SiO₂ glass exhibits excellent thermal stability, extremely low optical absorption, and high light transmittance, while also possessing strong chemical stability and extremely low dielectric loss. It is widely used in semiconductors, photolithography, and micro-optical devices. However, the stress sensitivity of traditional mechanical joints and the poor weather resistance of adhesive bonding make conventional methods unsuitable for glass joining. Welding technology, with its advantages of high joint strength, structural integrity, and scalability for mass production, has emerged as a key approach for precision glass joining. In the field of glass welding, technologies such as glass brazing, ultrasonic welding, anodic bonding, and laser welding are being widely studied and applied. With the advancement of laser technology, laser welding has emerged as a key solution to overcoming the bottlenecks of conventional processes. This paper, along with the application cases for these technologies, includes an in-depth study of common issues in glass welding, such as residual stress management and interface compatibility design, as well as prospects for the future development of glass welding technology. Full article

We developed dye-sensitized solar cells based on anatase–titanium dioxide (A-TiO₂) nanotubes (TiNTs) and nanocubes (TiNcs) with {001} crystal facets generated using simple and facile electrochemical anodization. We also demonstrated a simple way of developing one-dimensional, two-dimensional, and three-dimensional self-assembled TiO₂ nanostructures via electrochemical anodization, using them as an electron-transporting layer in DSSCs. TiNTs maintain tubular arrays for a limited time before becoming nanocrystals with {001} facets. Using FESEM and TEM, we observed that the TiO₂ nanobundles were transformed into nanocubes with {001} facets and lower fluorine concentrations. Optimizing the reaction approach resulted in better-ordered, crystalline anatase TiNTs/Ncs being formed on the Ti metal foil. The anatase phase of as-grown TiO₂ was confirmed by XRD, with (101) being the predominant intensity and preferred orientation. The nanostructured TiO₂ had lattice values of a = 3.77–3.82 and c = 9.42–9.58. The structure and morphology of these as-grown materials were studied to understand the growth process. The photoconversion efficiency and impedance spectra were explored to analyze the performance of the designed DSSCs, employing N719 dye as a sensitizer and the I⁻/I³⁻ redox pair as electrolytes, sandwiched with a Pt counter-electrode. As a result, we found that self-assembled TiNTs/Ncs presented a more effective photoanode in DSSCs than standard TiO₂ (P25). TiNcs (0.5 and 0.25 NH₄F) and P25 achieved the highest power conversion efficiencies of 3.47, 3.41, and 3.25%, respectively. TiNcs photoanodes have lower charge recombination capability and longer electron lifetimes, leading to higher voltage, photocurrent, and photovoltaic performance. These findings show that electrochemical anodization is an effective method for preparing TiNTs/Ncs and developing low-cost, highly efficient DSSCs by fine-tuning photoanode structures and components. Full article

Polymer binders are crucial components in providing both mechanical support and chemical stability to the structure of porous Li-ion electrodes. Particularly in silicon anodes, the active material undergoes substantial volume expansion of up to 275%. Due to the mechanical constraint of the current collector, these silicon materials tend to expand in the normal direction while exhibiting substantial particle rearrangement and plastic deformation. Conventional rigid binders such as polyacrylic acid (PAA) and polyimide (PI), while providing satisfactory initial capacity, do not eliminate diminished long-term performance. Our research attempts to develop binder formulations that can accommodate sufficient flexibility for the substantial volume changes of silicon particles. Specifically, we explore the use of short-chain polymer binders and a strategic blend of binders with different molecular weights. Experiments have demonstrated that cells combining both long- and short-chain PAA binders delivered an initial capacity of 2200 mAh/g at a 0.1C rate, compared to 1700 mAh/g for pristine PAA cells. Initial work indicated that shorter polymer chains might compromise the adhesion to the current collector, so we developed a multilayer anode (MLA) structure to mitigate this issue. Nevertheless, at this early stage of development, there was no observed increase in cycling performance for the MLA electrodes. Full article

In this study, highly ordered titanium dioxide nanotubes (TiO₂-NTs) have been synthesized using the electrochemical anodization procedure. Subsequently, the TiO₂-NTs were successfully decorated with PbS nanoparticles (NPs) using the pulsed KrF-laser deposition (PLD) technique under vacuum and under different Helium background pressures (P_He) ranging from 50 to 400 mTorr. The prepared samples (PbS-NPs/TiO₂-NTs) were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV–Vis and photoluminescence spectroscopies. XRD analyses confirmed that all TiO₂-NTs crystallized in the anatase phase, while the PbS-NPs crystallized in the cfc lattice. The average crystallite size of the (200) crystallites was found to increase from 21 to 33 nm when the pressure of helium (PHe) was raised from vacuum to 200 mTorr and then dropped back to ~22 nm at P_He = 400 mTorr. Interestingly, the photoluminescence intensity of the PbS-NPs/TiO₂-NTs samples was found to start diminishing for P_He ≥ 200 mTorr, indicating a lesser recombination rate of the photogenerated carriers, which also corresponded to a better photocatalytic degradation of the Amido Black (AB) dye. Indeed, the PbS-NPs/TiO₂-NTs samples processed at P_He = 200 and 300 mTorr were found to exhibit the highest photocatalytic degradation efficiency towards AB with a kinetic constant 130% higher than that of bare TiO₂-NTs. The PbS-NPs/TiO₂-NTs photocatalyst samples processed under P_He = 200 or 300 mTorr were shown to remove 98% of AB within 180 min under UV light illumination. Full article

Understanding and accurately modelling mass transport phenomena in anode-supported solid oxide fuel cells (SOFCs) is essential for improving efficiency and mitigating performance losses due to concentration polarization. This study presents a one-dimensional, isothermal, multi-component diffusion framework based on the Stefan–Maxwell (SM) formulation to evaluate hydrogen, water vapour, and nitrogen transport in two different porous ceramic support materials: calcia-stabilized zirconia (CSZ) and magnesia magnesium aluminate (MMA). Both SM binary and SM ternary models are implemented to capture species interactions under varying hydrogen concentrations and operating temperatures. The SM formulation enables direct calculation of concentration polarization as well as the spatial distribution of gas species across the anode support’s thickness. Simulations are conducted for two representative fuel mixtures—20% H₂ (steam-rich, depleted fuel) and 50% H₂ (steam-lean)—across a temperature range of 500–1000 °C and varying electrode thicknesses. They are validated against experimental data from the literature, and the influence of electrode thickness and fuel composition on polarization losses is systematically assessed. The results show that the ternary SM model provides superior accuracy in predicting overpotentials, especially under low-hydrogen conditions where multi-component interactions dominate. MMA consistently exhibits lower polarization losses than CSZ due to enhanced gas diffusivity. This work offers a validated, computationally efficient framework for evaluating mass transport limitations in porous anode supports and offers insights for optimizing electrode design and operational strategies, bridging the gap between simplified analytical models and full-scale multiphysics simulations. Full article