Search Results (12)

A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a fluorosilane ethanol solution, the surface exhibited superhydrophobicity with a contact angle of 154°. Subsequently, the anodic oxidation process formed an anodic oxide film dominated by an array of aluminum oxide (Al₂O₃) nanopores at the submicron scale. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the nanopore structures uniformly and continuously covered the laser-ablated layer. This hierarchical structure significantly increased the surface water contact angle to 162°. Wettability analysis showed that the prepared composite coating formed an air layer accounting for 91% of the surface area. Compared with the sample only treated by femtosecond laser etching, the presence of the Al₂O₃ nanopore structure significantly enhanced the mechanical durability, superhydrophobic durability, and corrosion resistance of the superhydrophobic surface. The proposed multi-step fabrication strategy offers an innovative method for creating multifunctional, durable superhydrophobic coatings and has important implications for their large-scale industrial use. Full article

Electrocatalytic urea oxidation reaction (UOR) is a promising dual-purpose approach for hydrogen production and wastewater treatment, addressing critical energy and environmental challenges. However, conventional anode materials often suffer from limited active sites and high charge transfer resistance, restricting UOR efficiency. To overcome these issues, a novel NiP@PNC/NF electrocatalyst was developed via a one-step thermal annealing process under nitrogen, integrating nickel phosphide (NiP) with phosphorus and nitrogen co-doped carbon nanotubes (PNCs) on a nickel foam (NF) substrate. This design enhances catalytic activity and charge transfer, achieving current densities of 50 mA cm⁻² at 1.34 V and 100 mA cm⁻² at 1.43 V versus the reversible hydrogen electrode (RHE). The electrode’s high electrochemical surface area (235 cm²) and double-layer capacitance (94.1 mF) reflect abundant active sites, far surpassing NiP/NF (48 cm², 15.8 mF) and PNC/NF (39.5 cm², 12.9 mF). It maintains exceptional stability, with only a 16.3% performance loss after 35 h, as confirmed by HR-TEM showing an intact nanostructure. Our single-step annealing technique provides simplicity, scalability, and efficient integration of NiP nanoparticles inside a PNC matrix on nickel foam. This method enables consistent distribution and robust substrate adhesion, which are difficult to attain with multi-step or more intricate techniques. Full article

The transition toward sustainable and decentralized energy solutions necessitates the development of innovative bioelectronic systems capable of harvesting and converting renewable energy. Here, we present a novel photo-bioelectrochemical fuel cell architecture based on a biohybrid anode integrating laser-induced graphene (LIG), poly(3,4-ethylenedioxythiophene) (PEDOT), and isolated thylakoid membranes. LIG provided a porous, conductive scaffold, while PEDOT enhanced electrode compatibility, electrical conductivity, and operational stability. Compared to MXene-based systems that involve complex, multi-step synthesis, PEDOT offers a cost-effective and scalable alternative for bioelectrode fabrication. Thylakoid membranes were immobilized onto the PEDOT-modified LIG surface to enable light-driven electron generation. Electrochemical characterization revealed enhanced redox activity following PEDOT modification and stable photocurrent generation under light illumination, achieving a photocurrent density of approximately 18 µA cm⁻². The assembled photo-bioelectrochemical fuel cell employing a gas diffusion platinum cathode demonstrated an open-circuit voltage of 0.57 V and a peak power density of 36 µW cm⁻² in 0.1 M citrate buffer (pH 5.5) under light conditions. Furthermore, the integration of a charge pump circuit successfully boosted the harvested voltage to drive a low-power light-emitting diode, showcasing the practical viability of the system. This work highlights the potential of combining biological photosystems with conductive nanomaterials for the development of self-powered, light-driven bioelectronic devices. Full article

Bismuth-based materials that adhere to the alloy/dealloy reaction mechanism are regarded as highly promising anode materials for potassium-ion batteries due to their high volume-specific capacity and moderate reaction potentials. However, their commercial viability has been limited by the effects of structural collapse due to volume distortion and impeded electron conduction, resulting in rapid capacity decline. In this work, a carbon-coated nanosized BiPO₄ rod (BiPO₄@C) was designed and fabricated to overcome the aforementioned challenges through the architecture engineering and anionic-tuning strategy. In particular, the nanosized nanorods significantly reduce the volume expansion; the incorporation of the bulk and open-skeleton anion PO₄³⁻ serves to mitigate the considerable volume distortion and generates the high ionic conductivity product (K₃PO₄) to ameliorate the poor ionic transport due to the structural deformation. The elaborated BiPO₄ rods exhibit high specific capacity (310.3 mAh g⁻¹, at 500 mA g⁻¹), excellent cycling stability (over 700 cycles at 500 mA g⁻¹) and superior rate performance (137.8 mAh g⁻¹, at 1000 mA g⁻¹). Systematic ex-situ XRD and TEM, as well as kinetic tests, have revealed the “conversion-multistep alloying” reaction process and the “battery-capacitance dual-mode” potassium storage mechanism. Moreover, the thick electrodes showed excellent specific capacity and rate performance, demonstrating their significant application potential in the next generation of SIBs. Full article

Transition metals such as nickel and cobalt as an alternative to Pt and Pd can be used for oxygen evolution reactions (OERs) and hydrogen production reactions (HERs) in alkaline environments, facilitating green hydrogen production as a sustainable alternative to fossil fuels. In this study, an NiCo₂O₄ catalyst was produced by a sono-hydrothermal method using urea as a hydrolysis agent. The electrochemical performance of the catalyst-coated NiFelt electrode was evaluated at different KOH concentrations (0.25, 0.5, and 1 M) and four operating temperatures in the interval of 20–80 °C. The electrode characteristics were investigated via electrochemical spectroscopy (cyclic voltammetry, EIS, multistep chronopotentiometry, multistep chronoamperometry) using two different reference electrodes (Ag/AgCl and Hg/HgO), to obtain insight into the anodic and cathodic peaks. XRD, SEM, EDS, and TEM analyses confirmed the purity, structure, and nanoscale particle size (20–45 nm) of the NiCo₂O₄ catalyst. The electrode showed symmetric CV with Ag/AgCl, making this reference electrode more appropriate for capacitance measurements, while Hg/HgO proved advantageous for EIS in alkaline solutions due to reduced noise. The overpotential of the catalyst-coated NiFelt decreased by 108 mV at 10 mA/cm² compared to bare NiFelt, showing a good potential for its application in anion exchange membranes and alkaline electrolyzers at an industrial scale. Full article

Transition metal selenides have narrow or zero band-gap characteristics and high theoretical specific capacity. Among them, cobalt selenide and cobalt telluride have some typical problems such as large volume changes, low conductivity, and poor structural stability, but they have become a research hotspot in the field of energy storage and conversion because of their high capacity and high designability. Some of the innovative synthesis, doping, and nanostructure design strategies for CoSe_x and CoTe_x, such as CoSe-InCo-InSe bimetallic bi-heterogeneous interfaces, CoTe anchoring MXenes, etc., show great promise. In this paper, the research progress on the multistep transformation mechanisms of CoSe_x and CoTe_x is summarized, along with advanced structural design and modification methods such as defect engineering and compositing with MXenes. It is hoped that this review will provide a glimpse into the development of CoSe_x and CoTe_x anodes for alkali-ion batteries. Full article

In this work, we report the preparation of nanostructured electrodes based on dense arrays of vertically-aligned copper (Cu) nanowires (NWs) to be subsequently covered by cadmium telluride (CdTe) thin films, with great potential to be used within “substrate”-type photovoltaic cells based on A${}^{\mathrm{I}\mathrm{I}}$-B${}^{\mathrm{V}\mathrm{I}}$ heterojunctions. In particular, the multi-step preparation protocol presented here involves an electrochemical synthesis procedure within a supported anodic aluminum oxide (AAO) nanoporous template for first generating a homogeneous array of vertically-aligned Cu NWs, which are then further embedded within a compact CdTe thin film. In a second stage, we tested three deposition methods (vacuum thermal evaporation, VTE; radio-frequency magnetron sputtering, RF-MS; and electrochemical deposition, ECD) for use in obtaining CdTe layers potentially able to consistently penetrate the previously prepared Cu NWs array. A comparative analysis was performed to critically evaluate the morphological, optical, and structural properties of the deposited CdTe films. The presented results demonstrate that under optimized processing conditions, the ECD approach could potentially allow the cost-effective fabrication of absorber layer/collecting electrode CdTe/Cu nanostructured interfaces that could improve charge collection mechanisms, which in turn could allow the fabrication of more efficient solar cells based on A${}^{\mathrm{I}\mathrm{I}}$-B${}^{\mathrm{V}\mathrm{I}}$ semiconducting compounds. Full article

Layered Na_0.8Co_0.8Ti_0.2O₂ oxide crystallizes in the β-RbScO₂ structure type (P2 modification) with Co(III) and Ti(IV) cations sharing the same crystallographic site in the metal-oxygen layers. It was synthesized as a single-phase material and characterized as a cathode in Na- and Na-ion batteries. A reversible capacity of about 110 mA h g⁻¹ was obtained during cycling between 4.2 and 1.8 V vs. Na⁺/Na with a 0.1 C current density. This potential window corresponds to minor structural changes during (de)sodiation, evaluated from operando XRD analysis. This finding is in contrast to Ti-free Na_xCoO₂ materials showing a multi-step reaction mechanism, thus identifying Ti as a structure stabilizer, similar to other layered O3- and P2-Na_xCo_1−yTi_yO₂ oxides. However, charging the battery with the Na_0.8Co_0.8Ti_0.2O₂ cathode above 4.2 V results in the reversible formation of a O2-phase, while discharging below 1.5 V leads to the appearance of a second P2-layered phase with a larger unit cell, which disappears completely during subsequent battery charge. Extension of the potential window to higher or lower potentials beyond the 4.2–1.8 V range leads to a faster deterioration of the electrochemical performance. After 100 charging-discharging cycles between 4.2 and 1.8 V, the battery showed a capacity loss of about 20% in a conventional carbonate-based electrolyte. In order to improve the cycling stability, different approaches including protective coatings or layers of the cathodic and anodic surface were applied and compared with each other. Full article

The presented study successfully demonstrated advantages of multistep anodization of AA2024—T3. Coating properties and morphology were studied in detail for five anodization processes: a conventional Base process with a constant applied current density and processes with current density applied in one (OS1 and OS2) and five (MS1 and MS2) steps at different magnitudes during the ramp period. Due to lower oxygen infusion, processes MS1 and MS2 produced a more intact coating with reduced porosity and enhanced abrasion resistance and hardness. The presented results clearly demonstrate that starting anodization at a low voltage and then slowly ramping current density will form coatings with a higher aluminum/oxygen ratio and enhanced properties over a shorter period of processing. Full article

Highly sensitive and reproducible surface-enhanced Raman scattering (SERS) substrates are the main challenge for practical applications. In this work, an ordered and hierarchical Ag nanoparticles (Ag-NPs)-decorated Au nanotubes (Au-NTs) array was achieved based on a funnel-shaped pore anodic aluminum oxide (AAO) template-assisted strategy. First, funnel-pore-AAO templates were fabricated by further oxidation of conical-pore-AAO templates achieved by multistep anodization and etching. Then physical sputtering was used to assemble the Au-NTs and Ag-NPs using the as-prepared funnel-pore-AAO as sacrificial templates. SEM revealed abundant sub-10 nm neighboring gaps and sub-10 nm nanocavities at the bottom of the nanotubes because of the special shape of the AAO template, which resulted in abundant strong “hot spots” contributing to the sensitive SERS detection. The resultant hierarchical substrates manifested a SERS enhancement factor of 1.8 × 10⁷ and reproducible response to 10⁻¹¹ M rhodamine 6G and 10⁻⁸ M methyl parathion, showing potential in SERS-based rapid detection of trace pollutants in the environment. Full article

It is well-known that the structure and composition of the material plays an important role in the processes occurring at the surface. In this paper, a surface morphology of nanostructured oxide layers electrochemically grown on Ti15Mo, tuned by applying different anodization parameters, was investigated in detail. The one-step anodization of Ti15Mo alloy was performed at room temperature in an ethylene glycol-based electrolyte containing 0.11 M NH₄F and 1.11 M H₂O. Different anodization times (ranging from 5 to 60 min) and applied potentials (40–100 V) were tested, and the surface morphology, elemental content, and crystalline structure were monitored by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffractometry (XRD), respectively. The results showed that contrary to the multistep anodization of titanium foil, the surface morphology of anodic oxide obtained via the one-step process contains the nanoporous outer layer covering the nanotubular structure. What is more, the pore diameter (D_p) and interpore distance (D_int) of such layers exhibit different trends than those observed for anodization of pure titanium. In particular, at a certain potential range, a decrease in both D_p and D_int with increasing potential was observed. However, independently on the used anodization conditions, the elemental content of oxide layers remained similar, showing the amount of molybdenum at c.a. 15 wt.%. Finally, the amorphous nature of as-anodized layers was confirmed, and their optical band-gap was determined from the diffuse reflectance UV–Vis spectra. It was found that E_g is tunable to some extent by changing the anodizing potential. However, further thermal treatment in air at 400 °C resulted in the anatase phase formation that was accompanied by a significant E_g reduction. Therefore, we believe that the presented results will greatly contribute to the understanding of anodic formation of nanostructured functional oxide layers with tunable properties that can be applied in various fields. Full article

The recent increased interest in the various applications of superhydrophobic surfaces necessitates investigating ways of how this property can be enhanced further. Thus, this study investigated how superhydrophobic properties can be enhanced through the formation of anodic alumina nanostructures on 5052 aluminum alloy. A multistep anodizing process that alternates two different anodizing modes, mild anodization (MA) and hard anodization (HA), with an intermediate pore-widening (PW) process was employed. Multistep anodization was employed in two different ways: an MA → PW → HA process and an HA → PW → MA process. Both routes were conducted with PW durations of 40, 50, and 60 min. The well-defined nanostructures were coated with a self-assembled monolayer (SAM) of FDTS (1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane). The contact angle values of water droplets were maximized in the pillar-like nanostructures, as they have a less solid fraction than porous nanostructures. With this, the study demonstrated the formation mechanism of both nanoscale pillar and nanoscale hierarchical structures, the wettability of the superhydrophobic surfaces, and the relationship between PW duration time with wettability and the solid fraction of the superhydrophobic surfaces. Full article