Search Results (325)

Compared with mass spectrometry or high-performance liquid chromatography (HPLC), surface-enhanced Raman scattering (SERS) is a promising alternative technique for inspection of preservatives in food safety. However, conventional SERS substrates based on metallic nanoparticles commonly suffer from complicated fabrication processes, long processing times, and high costs. Therefore, we propose a high-density porous anodic aluminum oxide (AAO) substrate prepared by one-step anodization process combined with pore widening to increase number of SERS hotspots on template. Through a rapid one-step anodization process conducted at 25 °C, the processing time and efficiency are greatly improved compared to conventional low temperature of 0–10 °C and two-step anodization method. By lowering the anodization voltage to 20 V, a high-density porous substrate is achieved, effectively enhancing the SERS signal intensity. Furthermore, we demonstrated that SERS signal intensities are affected by multiple correlated structural factors and significantly improved by lower anodization voltage with pore widening. The analytical enhancement factor is calculated as 1.18 × 10⁵ to 1.44 × 10⁷ on an AAO substrate prepared at 20 V with pore-widening process for 1000 and 0.1 ppm p-hydroxybenzoic acid, respectively. For the preservative detection of p-hydroxybenzoic acid, a detection limit of 100 ppb is achieved by a high-density AAO substrate prepared at 20 V, which is far below the regulatory limit of 600 ppm. Full article

Enhancing the ampacity of existing overhead transmission conductors through surface heat-dissipation regulation is important for grid capacity expansion. Herein, a superhydrophobic radiative heat-dissipating conductor was fabricated by combining phosphoric acid anodization with low-surface-energy modification. Porous anodic aluminum oxide (AAO) layers were in situ constructed on ACSR conductors under different anodizing current densities and oxidation times, followed by modification with hexadecyltrimethoxysilane or 1H,1H,2H,2H-perfluorodecyltrimethoxysilane to obtain H-AAO and F-AAO conductors, respectively. The surface morphology, optical properties, wettability, electrical resistance, current-induced temperature rise, and aging stability were systematically evaluated. The porous AAO layer enhanced the broadband infrared emissivity of the conductor surface while maintaining relatively high solar-band reflectance. The F-AAO conductor exhibited a water contact angle of 164.9° and a sliding angle of 1.8°, confirming excellent super-hydrophobicity. At 450 A, the steady-state temperature of the F-AAO conductor decreased from 106.85 °C for the Bare conductor to 75.34 °C. Under a 70 °C temperature limit, the allowable current increased from 343.58 to 431.57 A, corresponding to a 25.6% enhancement. Moreover, the F-AAO conductor retained stable heat-dissipation performance after 28 days of thermal aging. These findings demonstrate that anodization-assisted surface engineering is a feasible strategy for improving radiative heat dissipation, environmental adaptability, and current-carrying performance of overhead transmission conductors. Full article

Triboelectric nanogenerators (TENG) show significant potential in pressure sensing by converting mechanical disturbances into electrical signals positively correlated with the magnitude of the applied force, yet their development as practical pressure sensors is severely hindered by the major drawback of only detecting transient mechanical inputs. Additionally, traditional dual-mode pressure sensors have typically required complex multilayer structures and time-consuming fabrication processes. Here, a simple dual-mode pressure sensor of novel structure integrated with TENG and anodic aluminum oxide (AAO) for both dynamic and static pressure detection is proposed. Nanoporous AAO is directly grown on an aluminum substrate to simplify the traditionally complex multi-layer structure of dual-mode pressure sensors. The AAO layer serves a dual functionality by acting as an active triboelectric layer that significantly enhances the triboelectric output performance while concurrently functioning as the capacitive dielectric layer. A polydimethylsiloxane (PDMS) film is employed as the elastic counterpart to pair with the AAO substrate. The influence of PDMS thickness on the charge accumulation and extraction of the TENG mode is investigated to optimize the device output. Under optimal configurations, the streamlined Al-AAO/PDMS sensor demonstrates good sensitivity and linearity (R² > 0.99) for both dynamic triboelectric voltage (1.05 V/kPa) and static capacitance (5.56 pF/kPa) over a wide sensing range of 1–73 kPa. This dual-mode sensor effectively overcomes the transient limitation of conventional single-mode TENGs and shows significant potential for future smart tactile applications. Full article

A capacitor electrode has been developed, obtained by electrophoretically filling the nanosized pores of anodic alumina with carbon particles and PVDF. By pre-thinning the barrier anode layer, direct contact of carbon with the aluminum current collector has been achieved. The multilayer electrode from {carbon particles and PVDF}/{carbon black and porous AAO}/{aluminum current collector} was studied using Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and atomic force microscopy. The analyses demonstrate the highly developed surface of the electrodes and the good binding ability of the PVDF. The electrochemical properties of the electrodes were investigated in a 0.5 M Na₂SO₄ aqueous electrolyte using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge. The electrode allows operation at a high voltage window of 5.75 V. The electrochemical results show that the electrodes have a specific capacitance of 4.25 ± 0.35 F g⁻¹, a specific energy density of 19.3 Wh kg⁻¹ and specific power of about 5600 W kg⁻¹ with stable operation over 10,000 cycles. Therefore, the strategy of using electrophoretic deposition of carbon materials seems promising for obtaining inexpensive capacitive layers with good adhesion to aluminum, operating stably in a wide voltage window. Full article

As anodized aluminum components are increasingly deployed in high-power optical and precision industrial systems operating in non-vacuum environments, their outgassing behavior has emerged as a critical material reliability concern. In contamination-sensitive optical assemblies, released volatiles can accumulate on nearby surfaces, leading to haze formation, scattering, and progressive optical degradation. The porous anodic oxide layer retains water, hydrogen, dyes, and processing residues that are released under thermal, photonic, and environmental stresses typical of industrial operation. While most qualification data remain vacuum-centric, equivalent evaluation frameworks for ambient environments are limited. This review analyzes surface-driven desorption mechanisms relevant to non-vacuum systems and provides practical guidance for material and process engineers by evaluating mitigation strategies across the anodizing process chain, including fine-grain substrate selection, controlled anodizing with nickel acetate sealing, post-bake stabilization, and alternative dense coatings such as electroless nickel, sol–gel films, and Acktar. The analysis underscores the need for non-vacuum-specific qualification standards to support reliable material selection and long-term system performance. Full article

The electrolytic aluminum industry is facing severe challenges, such as excessive carbon consumption, resulting in more cost and environmental pollution due to the oxidation of carbon anodes. The isothermal oxidation resistance of B₄C-SiO₂-Albite (BSA) composite coating influenced by the in situ formation behavior and self-healing ability of the borosilicate glass at 1173 K was investigated through XRD, TG-DSC, Raman, FTIR spectroscopy, and SEM/EDS in this paper. The results show that the composite coating with 20 wt% B₄C has a relatively low mass gain rate of −0.082% after 24 h at 1173 K. It depends on the in situ formation of the amorphous borosilicate phase layer that can effectively protect the carbon anode from oxidation, which depends on the content of B₄C. The amorphous borosilicate glass forms from the reaction between the SiO₂ and the B₂O_3, from the oxidation of B₄C during exposure. More B₄C promotes the formation and volatilization of B₂O₃, which improves the viscosity and stability of the borosilicate glass by changing the glass network coupled with Na⁺ and Al³⁺ from Albite. It is a feasible strategy for designing durable coatings with appropriate B₄C addition for high-temperature applications. Full article

In nuclear power, marine engineering, and other fields, a matching system composed of duplex steel and copper alloy is a common combination for rotating components in a seawater environment. However, this system is susceptible to galvanic corrosion that seriously threatens its service safety and service life, with ZCuAl10Fe5Ni5 being the main component corroded. Additionally, current corrosion research on this system has evident gaps. Specifically, the influence of area ratio on galvanic corrosion remains insufficiently understood, and the action mechanism of Cl⁻ on the ZCuAl10Fe5Ni5-based corrosion product film in seawater, as well as the product evolution path, has not been fully revealed, which restricts the development of targeted protection technologies. This study explores the degradation mechanism of ZCuAl10Fe5Ni5 in a specific high-salinity environment (20,000 mg/L Cl⁻), characteristic of nuclear power plant service conditions. The results show that due to the significant electrode potential difference between the SAF2507 duplex steel and ZCuAl10Fe5Ni5 copper alloy, a stable galvanic couple is formed, with ZCuAl10Fe5Ni5 acting as the anode and undergoing dissolution corrosion. When the area ratio of ZCuAl10Fe5Ni5 (anode) to SAF2507 duplex steel (cathode) is 1:50, a significantly stronger galvanic effect is observed. The high concentration of Cl⁻ in seawater can damage the surface of the ZCuAl10Fe5Ni5-based corrosion product film, leading to intensified local corrosion. The ZCuAl10Fe5Ni5-derived corrosion products have a layered structure mainly comprising a mixed system of Cu-Al-Mg oxides/hydroxides, and the corrosion process is accompanied by selective aluminum depletion corrosion. This study provides insight into the corrosion mechanism and key influencing factors of ZCuAl10Fe5Ni5 in the matching system, as well as a theoretical basis and technical support for the design of compatibility metal materials in a seawater environment and the control of corrosion in ZCuAl10Fe5Ni5. Full article

This study reports the fabrication of porous anodic aluminum oxide (AAO) on a 6xxx series aluminum alloy by a two-step anodization route and systematically examines how anodization parameters govern the resulting morphology and wetting behavior. AAO samples were prepared in two groups: in Group 1, the anodization voltage was varied between 20 and 60 V at a fixed time of 60 min; in Group 2, the anodization time was varied between 30 and 120 min at a fixed voltage of 30 V. All anodizations were carried out in 0.3 M oxalic acid at room temperature. The AAO structures were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. The pore diameters and interpore distances were found to be 13.3–40.6 nm and 45.3–86.7 nm, respectively, in Group 1, and 19.1–23.6 nm and 41.0–44.4 nm in Group 2. Analysis of SEM images reveals that increasing the anodization voltage results in larger pore diameters, interpore spacings, and porosity, but a reduced pore density. In contrast, changes in anodization time at a fixed voltage have a more modest effect on pore geometry. The anodized surfaces exhibit a marked change in wettability, with the water contact angle increasing from ~45° for the non-anodized alloy to ~123° for the best-performing AAO surface, without any additional chemical modification. These results demonstrate that, even under simple room-temperature conditions, AAO morphology and hydrophobic behavior can be tuned in a predictable manner by appropriate choice of anodization parameters, which is relevant for the design of membranes, sensors, and functional surface coatings. Full article

The high reactivity of lanthanide metals poses a challenge to the electrochemical anodizing of surfaces for nanostructured coatings. This paper presents the first systematic experimental investigation of anodic oxidation of lanthanide gadolinium in aqueous solutions of citric, boric, oxalic, and tartaric acids. The voltage-current-time responses of anodizing of gadolinium, Al/Gd and Al/Nb/Gd systems were investigated. Anodic thin films were characterized using modern analysis techniques: SEM, FIB, and EDX. Morphology and voltage-current-time response analysis of anodized Al/Nb/Gd systems made it possible to establish the niobia cork-like effect and to develop a growth model. Full article

Low-dimensional lead-free metal halide perovskites have demonstrated excellent performance in indirect X-ray detectors; however, the imaging resolution remains limited due to the lack of effective scintillation waveguiding. In this work, array-structured scintillation screens were fabricated using anodic aluminum oxide (AAO) templates via a spatial confinement–assisted in situ growth strategy. The resulting directional optical confinement effect significantly enhances the scintillation performance of the screen. The fabricated Cs₃Cu₂Br_1.25I_3.75-AAO scintillator arrays achieve a spatial resolution of 14.10 lp/mm and a minimum detectable dose rate of 243 nGy/s under X-ray irradiation. In addition, the scintillator arrays exhibit excellent radiation stability, providing a reliable and cost-effective solution for high-resolution array-based X-ray imaging. Full article

Owing to the excellent performance of zinc oxide materials under ultraviolet light, this paper proposes a process for fabricating ZnO/Au heterojunction nanostructures on the surface of silicon-based solar cells using anodic aluminum oxide as the template, ultimately resulting in a novel silicon-based solar cell with an embedded ZnO/Au nanostructure array. Through model optimization and analysis of the solar cells, it is found that compared with silicon-based solar cells with double grating nanostructures, silicon-based solar cells with surface silicon nanostructure arrays prepared by similar processes, and traditional planar silicon-based solar cells, the light absorption efficiency of the proposed solar cell structure is improved by 13.2%, 35.01%, and 63.78%, respectively; its short-circuit current density and power conversion efficiency reach 40 mA/cm² and 20.17%, respectively. Meanwhile, this paper conducts an in-depth study on the performance enhancement mechanism, providing new insights for the fabrication of ZnO/Au heterojunction nanostructures and their applications in the field of solar cells. Full article

This study focuses on sulfuric acid-anodized films formed on 2A12 and 6061 aluminum alloys, in which the corrosion behavior of the oxide films under different film thicknesses, sealing methods, and defect states was investigated through neutral salt spray testing combined with surface morphology characterization and XRD analysis. The results indicate that the corrosion resistance of anodic oxide films is positively correlated with film thickness, while the anodized film on 2A12 aluminum alloy contains more cracks than that on 6061, which can readily serve as long-term corrosion initiation sites. Although the corrosion products of both alloys are identified as Al₂O₃ and AlO(OH), the oxide films on 6061 aluminum alloy exhibit higher compactness than those on 2A12 at all investigated thicknesses, resulting in superior resistance to neutral salt spray corrosion, and both sealing methods provide effective protection for the 6061 aluminum alloy substrate. This study provides experimental and theoretical references for the development and application of anodizing processes for aluminum alloys in chloride-containing marine environments. Full article

Pharmaceutical contamination poses growing environmental risks, yet industrial adoption of advanced oxidation processes (AOPs) remains limited by high costs and the environmental impacts associated with specialized electrodes. This study demonstrates that unmodified aluminum electrodes achieve pharmaceutical degradation performance comparable to precious metal systems at dramatically reduced cost and carbon footprint. An aluminum-based electro-Fenton (EF) system was optimized for amlodipine (AML) removal through systematic evaluation of operational parameters. Under optimized conditions (pH 2.7, 35 mg L⁻¹ FeCl₃, 1.3 mM NaCl, 5 V), the system achieved 97% AML degradation within 15 min, following pseudo-first-order kinetics ($k=0.15$ min⁻¹). The mechanism combines hydroxyl radical oxidation with synergistic electrocoagulation resulting from anodic Al³⁺ release and cathodic Fe²⁺ regeneration. Sustainability assessment revealed exceptional performance: an energy consumption of 0.32 kWh m⁻³, a carbon footprint of 0.53 kg CO₂-eq m⁻³ (60–75% lower than conventional AOPs), and operational costs of $0.71–1.05 m⁻³. Aluminum electrodes cost 100× less than platinum alternatives, with the generated Al(OH)₃ sludge offering valorization potential. This work demonstrates that high-performance electrochemical remediation is achievable using Earth-abundant materials, providing a scalable and cost-effective alternative for pharmaceutical wastewater treatment in resource-constrained settings. Full article

Traditional colloid SERS substrates are mostly based on metal nanoparticles (MNPs), which have complex and time-consuming fabrication processes, poor structural control, and are susceptible to oxidation. As a result, solid-state SERS substrates have emerged as an effective alternative. Here, we propose using two-step mild and hard anodization to fabricate ordered anodic aluminum oxide (AAO) substrates with high total pore circumference for SERS detection. Hybrid pulse anodization (HPA) enables the fabrication of AAO at room temperature using 40 V in the first step and 40, 110, and 120 V in the second step of anodization. The different voltages applied in the second step effectively control the pore diameter, thereby achieving various nanostructures. The enhancement mechanism primarily originates from the high total pore circumference of nanostructures, which generates abundant hot spots around the pore peripherals, thereby significantly amplifying the SERS signal. Sorbic acid is a common preservative widely used in food products and employed as a test substance on high regularity AAO substrates at concentrations of 1000 ppm to 10 ppb. The resulting SERS spectra exhibited distinct characteristic peaks at 1640–1645 cm⁻¹. The analytical enhancement factor is calculated as 1.02 × 10⁵ at the AAO substrate prepared by 110 V with the Si substrate as the reference. By appropriately tuning the process parameters, a limit of detection (LOD) as low as 10 ppb of sorbic acid was achieved. Full article

We report a comprehensive study on the effect of H₂SeO₄ electrolyte temperature on the composition, defect, morphological, and luminescent properties of porous anodic aluminum oxide (AAO). An increase in the synthesis temperature led to a decrease in the AAO cell diameter from 85–115 nm to 38–58 nm (depending on the electrolyte concentration) and enhanced the etching of the AAO walls, which even resulted in the disintegration of the AAO into individual fibers at 40 °C. The selenium concentration in the samples formed in 0.5–1.5 M H₂SeO₄ in the temperature range of 5–40 °C did not exceed 2 at.% and fell below the detection limit at 40 °C. The formation of a nanocrystalline Al₂O₃ phase was observed in the H₂SeO₄ electrolyte at 40 °C. The samples exhibited weak photoluminescence. We identified three types of paramagnetic centers in AAO formed in H₂SeO₄: F⁺ centers (N_sF = 8.2 × 10¹⁵ g⁻¹), newly discovered centers with an unpaired electron localized on an oxygen atom (N_sO = 10¹⁷ g⁻¹), and centers associated with selenate radicals (N_sS = 6 × 10¹⁸ g⁻¹). By comparing the photoluminescence spectra and defect concentrations, we conclude that the luminescence of AAO formed in selenic acid is exclusively due to F⁺ centers, while other paramagnetic centers do not contribute. Full article