Dritsite-like layered double hydroxides (LDHs) were synthesized by reacting gibbsite with LiCl, followed by anion exchange with sodium salts of molybdate, tungstate, and chromate using two distinct procedures, that varied concentration and exchange time, to optimize oxoanion intercalation while minimizing delithiation. The obtained materials were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies and scanning electron microscopy (SEM). These characterization techniques confirmed the lamellar structure of the materials, with basal spacings consistent with those reported for dritsite-like LDHs, and evidenced the presence of characteristic chemical bonds associated with the constituent elements and intercalated oxoanions. In addition, ICP/OES analysis was used to quantify the release of intercalated species after 24 h and 7 days of immersion in NaCl solutions, showing partial lithium leaching (approximate to 1% of the total content) together with anion release (CrO42- 2.5%, MoO42- 0.2%, WO4 2- 0.1%). Electrochemical impedance spectroscopy on AA2024 aluminum alloy demonstrated that the protective performance of each material can be correlated with the concentration of anion released and differences in inhibition efficiency of the intercalated anion. This is the first report describing a dual release from LDH-like structure combining Li+ cations with well known oxoanions with different corrosion inhibition efficiency towards Al alloys. Furthermore, the present study shows that by proper controlling synthesis parameters it is possible to impart a joint release of ions from LDH structure, which can open new pathways for the preparation of novel LDH-like compositions.

This work reports a sustainable route for synthesizing a silver nanoparticle/reduced graphene oxide nanocomposite supported on activated carbon (AgNPs/rGO/AC810), using aqueous extract of guarana seed skins as a natural reducing and stabilizing agent. The extract promotes the reduction of Ag⁺ to silver nanoparticles (AgNPs) and graphene oxide (GO) to reduced graphene oxide (rGO), followed by deposition onto commercial activated carbon (AC810). UV–vis spectroscopy revealed the Ag surface plasmon resonance band and provided evidence of GO reduction to rGO, with the GO band at λmax ≈ 235 nm disappearing and a broad rGO band appearing at λmax ≈ 398 nm. XRD analysis revealed the face-centered cubic structure of metallic Ag with an average crystallite size of 11.39 nm. HR-TEM images showed uniformly dispersed spherical AgNPs anchored on rGO sheets and within AC810 pores, with average sizes of 8 nm in AgNPs/rGO and 13 nm in AgNPs/rGO/AC810. Raman and ATR-FTIR analyses supported the partial restoration of sp² domains, with ID/IG values of 1.20 for GO and 1.10 for AgNPs/rGO, and characteristic carbon functionalities. BET/BJH analysis revealed a high surface area of approximately 600 m² g⁻¹ and a predominantly mesoporous structure, favorable for active-site accessibility and mass transport. DLS/zeta potential results indicated colloidal stability under alkaline conditions, with hydrodynamic diameter around 240 nm and zeta potential near − 30 to − 35 mV. Electrochemical characterization showed a significant increase in ECSA from 0.003 cm² for GCE to 0.177 cm² for AgNPs/rGO/AC810/GCE, corresponding to an approximately 59-fold enhancement and a roughness factor increase from 0.03 to 1.77, indicating a high density of accessible active sites. These results indicate that AgNPs/rGO/AC810 is a low-cost and versatile nanocomposite platform for future CO₂RR studies.

This study investigates the macro- and micromechanical properties of epoxy-based nanocomposites containing Mg-Al/NO3 layered double hydroxides (LDHs), with a comparative evaluation of two preparation routes: solvent exchange and direct drying from an aqueous LDH slurry. LDHs were characterised using atomic force microscopy (AFM), scanning transmission electron microscopy, and X-ray diffraction methods. Tensile tests and AFM nanomechanical mapping were used to obtain the macro- and micromechanical properties of LDH/epoxy nanocomposites, respectively. Both preparation methods resulted in nanocomposites with comparable mechanical performance. Young's modulus increased by approximately 30-70% at lower LDH loadings (1-2 wt.%), and the ultimate tensile strength remained largely unchanged compared to pure epoxy. At higher LDH contents, tensile strength decreased by approximately 15-26%, while fracture strain decreased by up to 54%, which was attributed to particle aggregation, as confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The mechanical response and stiffness maps obtained by the peak force AFM nanomechanical mapping revealed that nanocomposites prepared using solvent-exchanged LDHs exhibit significantly narrower interfacial widths and higher stiffness compared to those made by the conventional approach, indicating improved interfacial bonding and mechanical performance. Overall, the solvent-exchange approach proved effective for improving the interfacial properties and stiffness of epoxy/LDH nanocomposites.

The control and modification of the surface’s wettability is a surface engineering task demanded by several applications that use material as metals like copper. Laser irradiation is a well-explored technique to modify the roughness of the surfaces which is required to modify their wettability. Despite this, the obtention of superhydrophobic surfaces also requires modification of the surface chemistry, which is achieved only through aging after irradiation or additional chemical functionalization using methods that, in most of the case, involve the use of “forever chemicals”. Here we present a new single step method that allows simultaneous control of the roughness and the functionalization of copper with lauric acid that is non-toxic and presents good biocompatibility. The samples achieve superhydrophobicity in less than a day after production and independently of the atmosphere where the samples are stored, a factor that is not taken into consideration is several of the previous studies. They revealed self-cleaning abilities even after some scratches were inflicted on the surface. The method can be extended to other metals opening the avenue for new surfaces with non-fluorinated compounds and wettability and biocompatibility properties suitable for new applications.

The spectroscopic and electrochemical properties of copper (Cu) superhydrophobic surfaces produced from laser scribing operating in the nanosecond pulsing regime are reported herein. mu -Raman spectroscopy highlighted the synthesis of copper oxide films with the simultaneous sharp increase of the substrates' specific surface area through one single laser processing step. Higher laser power densities resulted in cupric oxide (CuO) with higher crystallinity and more homogeneous surface chemistry, whereas cuprous oxide (Cu2O) dominates surfaces processed at lower laser power densities. Steady-state contact angles using water of 162 degrees +/- 9 degrees were measured for the lowest laser power employed, representing a grounded and meaningful development for substrates of this kind using laser technology. The results show that the combination of surface roughness and the presence of Cu2O and hydrocarbon chains at the surface contributed to the superhydrophobicity of the copper foils. Additionally, variations in the thermal conductivity of the samples' surface are influenced by changes in the chemical composition. The surfaces were exposed to limestone-rich water and the amount of deposited solute was quantified using atomic absorption spectrometry. A fivefold reduction in calcium carbonate (CaCO3) was observed, unequivocally demonstrating the impact of laser treatments in reducing CaCO3 nucleation rates in Cu for water heating applications.

Metal corrosion is a colossal technical, economic, and environmental challenge worldwide. Protective coatings containing corrosion inhibitors (CIs) are commonly used to address this natural process, particularly severe in immersed structures in seawater. However, high-performance CIs, such as benzotriazole (BTA), often exhibit toxicity towards aquatic organisms and leach prematurely. This study introduces safe and sustainable-by-design engineered nanomaterials, specifically layered double hydroxides loaded with BTA (Mg-Al LDH-BTA and Zn-Al LDH-BTA), as an innovative and eco-friendly approach compared to state-of-the-art CIs. This study aims to characterize both nanomaterials, assess their anti-corrosion performance when incorporated in polyurethane coatings, and evaluate their environmental behavior when dispersed in water, short-term acute and chronic effects on temperate marine species, and the environmental hazard. Key findings include a superior anti-corrosion performance of coatings containing Zn-Al LDH-BTA compared to BTA-coatings. Aqueous dispersions of nanomaterials exhibit instability of particle size and zeta potential over time, while concentrations of metals (Al, Zn) and nitrates reach high levels in the highest tested concentration due to partial dissolution, which may explain the observed toxicity patterns (median effect concentrations in the mg L-1 range). The tested compounds were not toxic for most tested species, apart from bacteria (Aliivibrio fischeri) and/or echinoderms (Paracentrotus lividus) and, in case of Mg-Al LDH-BTA, also on two microalgae species. The highest statistical PNEC value was observed for Mg-Al LDH-BTA (PNEC = 0.326 mg BTA per L), while the highest deterministic PNEC value was found for Zn-Al LDH-BTA (PNEC = 0.00041 mg BTA per L). These findings indicate that both nanomaterials are environmentally sound and efficient alternatives for anti-corrosion maritime applications.

Laser patterning has emerged as a remarkable method for tuning the surface properties of materials, including metals such as copper and its alloys. The copper wettability can be precisely tailored - from superhydrophilic to superhydrophobic – using laser-based surface engineering techniques, unlocking transformative potential across a wide range of applications. This review provides a comprehensive overview of the application of laser technology in the modification of the wettability properties of copper surfaces. Particular attention is given to the evolution of the water contact angle over time of irradiated surfaces after air exposure, as well as to the mechanisms reported in the literature that explain wettability changes. In addition to laser irradiation, spanning wavelengths from ultraviolet to infrared and pulse widths from the nanoseconds to femtoseconds, several studies incorporate post-processing methods to achieve the desire performance, which are also discussed in this review. Moreover, the review highlights successful application of the laser-treated copper surfaces modified with wettability in areas such as oil-water separation, self-cleaning, anti-icing, sensing, heat transfer and microfluids, among others. Finally, a critical analysis of laser surface treatments and conventional chemical methods is performed.

This study addresses the fundamentals of corrosion inhibition of AA2024 alloy by tannic acid (TA), a Cr-free and eco-friendly natural product. To this end, the AA2024 alloy was immersed in NaCl solution (50 mM) with different TA concentrations (0.1-10 mM) for 7 days. Surface (SEM, Raman, and SKPFM) and electrochemical analyses (EIS, PDP, and SVET) revealed mixed inhibition after 1 day of immersion in TA solution. Long-term immersion tests in TA solutions produced a tannate-rich oxide film on the surface. The films with low tannate content (formed in 0.1 and 1 mM TA) showed the highest stability and corrosion resistance.

The wettability of copper can be modified using laser patterning, allowing the surface to achieve a superhydrophobic behavior after aging in ambient conditions or in a faster way when combined with a green engineering method (heating in an ethanol bath). The surface chemistry of copper irradiated with a 355 nm pulsed laser was studied using Raman spectroscopy and Fourier transform infrared measurements allowing to discuss the mechanism responsible for the wettability change. It was found that the adsorption of organic compounds rather, than the reduction of CuO to Cu2O previously presented in the literature as the dominant effect, is what plays a key role in this process. Moreover, the superhydrophobic copper presents an ability to delay the formation of patina allowing the copper surface to keep its electrical conductivity for a longer time when compared with non-irradiated copper exposed to the same conditions. Copper and its alloys are widely used in applications that take advantage of their electrical conductivity, so the reported strategy to maintain the electrical conductivity of the surface presents remarkable interest.

Driven by the recent discovery of tannic acid (TA) as an effective green corrosion inhibitor for AA2024 alloy, this study evaluates its suitability as an additive for epoxy (EP) and polyurethane (PU) coatings, both through direct addition and by immobilization into layered double hydroxides (LDH-TA). LDH-TA was characterized by XRD, FTIR, and UV-visible spectrophotometry. Also, its anticorrosion performance was evaluated using EIS. The results show that the direct addition of TA to EP and PU coatings reduces their barrier properties, whereas incorporating LDH-TA into the polyurethane matrix provides superior corrosion protection compared to the epoxy coating. Therefore, LDH-TA-loaded PU coating (PU-LDH-TA) was further characterized through rheology analysis, surface characterization, release studies, and electrochemical techniques (EIS and SVET). The findings indicate that after 28 days, |Z| at 10-2 Hz for PU-LDH-TA remains over one order of magnitude higher than PU. Besides, upon coating defects, tannate anions released from the polyurethane coating form a protective Al/tannate-rich hydroxide layer at the defect site. Thus, PU-LDH-TA demonstrates effective active corrosion protection in saline media while maintaining the structural integrity of the coating.

This study investigates the environmental impact and corrosion inhibition of novel double-chain arginine-based cationic surfactants developed as antimicrobial agents. The research focuses on asymmetric double-chain surfactants (LANHCx) with a 12-carbon alkyl chain and a second chain of 3-10 carbons, linked to the amino acid polar head group via amide bonds. The study assessed how alkyl chain length affects the ecological properties. Aerobic biodegradability (CO2 headspace test) and aquatic toxicity (short-term exposure on Daphnia magna, Aliivibrio fischeri, Tetraselmis chuii, and Phaeodactylum tricornutum) were evaluated. Corrosion inhibition efficiency was determined using electrochemical impedance spectroscopy (EIS). Alkyl chain length significantly influenced biodegradation rates (1-63 % at 12 mg C/L), with the C6 homologue showing minimal degradation, though it improved at lower concentrations. Biodegradation correlated with antimicrobial potency. These compounds exhibited over one order of magnitude lower aquatic toxicity than conventional quaternary ammonium surfactants (QACs). The arginine-based surfactant LANHC6 effectively inhibited carbon steel corrosion in neutral conditions (80 % at 0.5 mM), outperforming conventional DTAC at a 32-fold lower concentration. Overall, these new amino acid-derived antimicrobial agents demonstrate higher biodegradation rates and lower toxicity compared to conventional QACs, making them promising alternatives as environmentally preferable corrosion inhibitors.

Metallic corrosion is an unsolved economic and environmental problem, mitigated with coatings often containing toxic corrosion inhibitors. This study aims to extensively assess two eco-friendly and efficient anti-corrosion nanomaterials for maritime applications, specifically layered double hydroxides containing nitrite (Mg-Al LDH-NO2 and Zn-Al LDH-NO2) in terms of anti-corrosion performance, ecotoxicity, and environmental behavior and risk, along with a novel polyurethane coating. In aqueous dispersions, both LDHs behave as stimuli-responsive materials: unstable, tendency to rapidly aggregate and sink and release chemicals through anionic exchange and partial dissolution. Both nanomaterials presented negligible toxicity to most species, except microalgae Isochrysis galbana. Zn-Al LDH-NO2 also caused effects on the gastropod Phorcus lineatus and the echinoderm Paracentrotus lividus, being the most hazardous compound. Considering the environmental concentration of NO2 -, reported in the literature for well-oxygenated open ocean waters, and the statistically predicted no effect concentrations, tested chemicals potentially represent no environmental risk. The novel coating containing Zn-Al LDH-NO2 showed improved corrosion protection of carbon steel when benchmarked with state-of-the-art coatings. Leachates from these coatings also caused no/low ecotoxicological effects, attributed to the low release of chemicals over four weeks of immersion. These breakthroughs demonstrate that these novel ENMs are environmentally promising anti-corrosion nanoadditives for maritime coatings.

In this work biodegradable Mg1Ca alloy underwent surface modification using hydroxyapatite (HAp), aluminium oxide (Al2O3), and treatments with phosphoric (H3PO4), hydrofluoric (HF), and acetic (CH3COOH) acids. The resulting surface-treated Mg substrates were assessed in terms of phase content and chemical composition through X-ray diffraction (XRD) and glow discharge optical emission spectrometry (GDOES). Additionally, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to examine the surface's topography and structure, while the corrosion behavior and cytotoxicity were surveyed using electrochemical impedance spectroscopy (EIS), alongside WST-1 reduction and lactate dehydrogenase (LDH) release assays on L929 mouse fibroblasts. The findings indicated that the surfaces of all samples were uniformly structured, while chemical analysis of the treated surfaces suggested the presence of mostly thin films. Furthermore, EIS results highlighted that the HAp-treated Mg1Ca alloy exhibited superior corrosion resistance, and the cytotoxicity assessment of Mg1Ca-HAp and Mg1Ca-H3PO4 alloys showed minimal cytotoxic effects on mouse fibroblasts, compared to other treated surfaces, suggesting enhanced biocompatibility of those two surface treatments. Overall, this constitutes the first comparative study of different surface treatments developed on biodegradable Mg1Ca alloy, aiming to identify optimal modification strategies for biomedical applications.

Mediterranean olive cultivation, a cornerstone of regional agriculture, is increasingly threatened by intensified farming practices, emergent vascular diseases, and severe climate change pressures, particularly drought and heat. Microbial biostimulants, specifically PGPB, offer a critical, nature-positive solution by enhancing nutrient acquisition, improving stress tolerance, and conferring biocontrol capacity to the host tree. Early studies on Olea europaea confirm the fundamental potential of these beneficial microorganisms to support olive health. This review argues that the widespread failure of conventional PGPB applications (e.g., soil drenching) in mature olive groves is not primarily a biological issue, but rather an engineering challenge. The application methods cannot effectively overcome the hostile belowground environment, intense native microbial competition, and the physical barriers of the tree’s mature root and stem architecture. To unlock the full potential of PGPB for sustainable olive production, a fundamental shift in research priority is required. Future strategies must focus on advanced engineering solutions: (1) developing robust, protective nanostructured carriers to ensure microbial viability and controlled release in harsh environments; and (2) pioneering non-root delivery systems, most notably endovascular delivery (endotherapy), to bypass the soil barrier and precisely target the tree’s vascular system. This review synthesizes the biological promise of PGPB in the olive sector, critically analyzes the application failures of traditional methods, and outlines a comprehensive research agenda centered on engineered delivery systems as the essential key to a resilient and sustainable future for olive cultivation under climate change.

The machine learning framework reported herein can greatly accelerate the development of more effective and sustainable corrosion inhibitors for aluminum alloys, which still rely mostly on the experience of corrosion scientists, and trial and error laboratory testing. It can be used to design inhibitors for specific applications, which can be immobilized into nanocontainers or included directly into coatings in the search for less hazardous corrosion protective technologies. Therefore, a machine learning (ML) classification model that allows to identify promising compounds ( > 70% inhibitor efficiency) among less promising ones, and an online application (https://datacor.shinyapps.io/datacortech/) were developed for the virtual screen (simulation) of potential inhibitors for aluminum alloys, capable of considering the molecular structure and the influence of pH as an input.

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This study reports the development of anticorrosive bilayer coatings consisting of in situ grown layered double hydroxides (LDH) covered with a polyurethane layer on a steel substrate. This design aims at providing corrosion protection via the controlled release of gluconate from LDH near the substrate, while at the same time contributing to the improvement of the polyurethane layer coating adhesion. The CaAl-LDH thin film was initially grown directly on AISI 1080/1010 carbon steel and modified with environmentally friendly gluconate molecules through an ion-exchange reaction. The effect of polyurethane treatments on the LDHs thin film was systematically explored: gluconate is either intercalated in LDHs or dispersed in polyurethane coatings, and the two systems are studied to understand the role of inhibitors in bilayer coating systems at defined conditions. The structural characteristics of the developed coatings were evaluated by scanning electrochemical microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (ATR-FTIR), and glow discharge optical microscopy (GDOES). The findings of electrochemical impedance spectroscopy (EIS) measurements on coated carbon steel substrates in NaCl solution demonstrated the significance of the bilayer film design for long-term corrosion protection, by combining active corrosion protection provided by the LDH conversion film with the passive barrier effect against electrolyte species rendered by the organic polyurethane layer. Additionally, improving the polyurethane coating’s wet adhesion to the substrate when applied onto CaAl-LDH opens new directions toward the co-development of surface treatments with organic coatings.

Engineered nanomaterials (ENMs), such as silica mesoporous nanocapsules (SiNC), have emerged as a powerful tool for the controlled delivery and release of active compounds in various fields. However, the environmental impact of SiNC on marine biota, particularly when they enter the marine environment through wastewater effluents or direct release from maritime coatings, remains poorly understood. Studying their effects is thus crucial for environmental and human health protection, the development of safe-by-design ENMs, and informed policy-making. This study aims to assess the ecotoxicological effects and internalization of industrially-relevant SiNC in marine phytoplankton, namely on the microalgae Tetraselmis chuii, Nannochloropsis gaditana, and Isochrysis galbana, and diatoms Phaeodactylum tricornutum, and Chaetoceros calcitrans. For this purpose, a fluorescent nanocarrier (SiNC-UMB) is developed by labeling the SiNC with the fluorescent natural dye umbelliferone (UMB). UV-vis and fluorescence spectroscopic analyses confirmed the successful loading of UMB into SiNC. Phytoplankton can internalize these ENMs, even at low concentrations, although adsorption to the cell wall can also occur. This confirms the internal exposure and growth inhibition observed in the microalgae. These findings highlight the potential of using SiNC-UMB as a valuable tool for tracking their uptake and assessing their effects on marine biota and beyond. Silica mesoporous nanocapsules (SiNC) labeled with the fluorescent dye umbelliferone can be internalized by marine microalgae even at low concentrations, although adsorption to the cell wall may also occur. Ecotoxicological findings on five marine microalgae species suggest there is space for optimization to be safely used for tracking purposes and/or assessment of SiNC effects on biota. image

Nowadays, drug delivery systems (DDSs) are gaining more and more attention. Conducting polymers (CPs) are efficiently used for DDS construction as such systems can be used in therapy. In this research, a well-known CP, polypyrrole (PPy), was synthesized in the presence of the polysaccharide heparin (HEP) and chlorpromazine (CPZ) using sodium dodecyl sulfate (SDS) as electrolyte on a steel substrate. The obtained results demonstrate the successful incorporation of CPZ and HEP into the polymer matrix, with the deposited films maintaining stable electrochemical parameters across multiple doping/dedoping cycles. Surface roughness, estimated via AFM analysis, revealed a correlation with layer thickness—decreasing for thinner layers and increasing for thicker ones. Moreover, SEM images revealed a change in the morphology of PPy films when PPy is electropolymerized in the presence of CPZ and HEP, while FTIR confirmed the presence of CPZ and HEP within PPy. Due to its lower molecular mass compared to HEP, CPZ was readily integrated into the thin polymer matrix during deposition, with diffusion being unimpeded, as opposed to films with greater thickness. Finally, the resulting system exhibited the ability to release CPZ, enabling a dosing range of 10 mg to 20 mg per day, effectively covering the therapeutic concentration range.