Introduction

The global annual accumulation of food waste has been increasing in the last years. Thus, biomass-based catalysts have been selected as a solution to reduce this waste and obtain energy by water splitting process. Therefore, pyrolysis conditions have been optimised by Response surface methodology (RSM) to improve the obtain biochar properties and quality, diminishing overpotential and Tafel slope responses to deal with thermodynamic issues from water splitting. Moreover, our catalyst benefits for its simple coating, as the synthesized biochar is deposited into the selected support by drop deposition where the own material acts as adhesive agent, avoiding polymers as Nafion® or Sustainion®.

Methods

1 g of orange peel was pyrolysed in a tubular oven under different conditions, considering the reaction time (30-720 min) and the reaction temperature (300-900 ºC), with a heating rate of 10ºC/min. Thus, software DesignExpert® has been used for RSM, establishing both reaction temperature and time as input factors and overpotential and Tafel slope as response factors.

Results

Our results showed that the optimal pyrolysis conditions obtained by RSM were applying the highest temperature (900ºC) with the lowest treatment time (30 min), attaining the minimise overpotential (374.8 mV at 10 mA/cm²) for water splitting.

Conclusions

This work demonstrates competitive results in terms of overpotential and Tafel slope with the benchmark catalysts for water splitting, opening the importance of synthesis conditions optimization for catalytic properties.

Acknowledgments

This work was supported by Project H₂-ZeroWaste from AXA Research Fund and the project CINTECX-CHALLENGE 2024. Moreover, the researcher Aida M. Díez is grateful to Ramón y Cajal (RYC2023-044934-I) financial support (MICIU).

Introduction

Electrochemical water-splitting processes have arisen as an alternative for fighting energy source shortages through H₂ generation. However, this process requires the usage of catalysts in order to reduce the energy input. Metal organic frameworks (MOFs) are novel materials which may act as water-splitting catalysts due to their stability, crystal structure and high conductivity.

Methods

MOF NH₂-MIL-101(Fe) was synthetized through a solvothermal method (20 h, 110°C) using FeCl₃∙6H₂O, 2-aminoterephthalic acid and dimethylformamide. For the electrochemical water-splitting process assessment, different dosages of MOF-Fe were placed on the working electrode by different means (dropwise, dip-coating, ultrasonic dispersion), with Ni foam for alkaline and neutral pHs or carbon paper for acid pH (1 cm²), using graphite sticks and HgCl₂ electrodes as counter and reference electrodes, respectively. This three-electrode cell was connected to a PGSTAT302N potentiostat (Methrom).

Results

MOF-Fe was tested for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at neutral, acid, and alkaline pHs. MOF-Fe showed a high performance in the alkaline OER. Moreover, 0.25 mg/cm² was found to be the optimal MOF-Fe dosage. Thus, 10, 50 and 100 mA/cm² were obtained by applying low overpotentials of 300, 347 and 372 mV. This catalyst also exhibited high stability for 90 h at such current densities, defeating the benchmark catalyst (IrO₂) in both activity and stability. Characterization analysis showed that MOF-Fe's performance could be explained by its high crystallinity, elevated functional group presence, and great surface area.

Conclusions

The noble metal-free MOF-Fe was a suitable alternative for applying electrochemical water-splitting processes in a more environmentally friendly and economic approach, opening a path for the future application of these processes.

Acknowledgments

This work was supported by Project H2-ZeroWaste (AXA Research Fund). Aida Díez is grateful to Ramon y Cajal (RYC2023-044934-I)'s financial support (MICIU).

Graphene oxide (GO) has emerged as a carbon-based nanomaterial providing an alternative pathway to graphene. One of its most notable features is the ability to partially reduce it, resulting in graphene-like sheets through the removal of oxygen-containing functional groups. Herein, the effect of localized interactions in a Ag/GO/Au multilayer system was studied to explore its potential for photonic applications. The Ag/GO/Au structure was fabricated through a sequential deposition process. First, silver thin films (10 nm) were deposited onto glass substrates using a DC magnetron sputtering system. Subsequently, graphene oxide (GO) layers (8 nm) were applied onto the silver films via a dip-coating technique. Finally, gold thin films (15 nm) were deposited over the GO/Ag/glass substrates using the same sputtering system. Micro-Raman Spectroscopy, SEM (Scanning electron microscopy) and Variable Angle Ellipsometry measurements were performed on the Ag/GO/Au structure.

Micro-Raman measurements confirmed that the atomic frame of sp² carbon formed in RGO (reduced graphene oxide), thus indicating the transition from sp³ (oxidized regions) to sp² (graphitic regions) hybridization.

An interesting behavior of the GO dip-coated on magnetron sputtered silver with the formation of Ag nanostructures on top of the GO layer was reported using SEM . Furthermore, the dispersion laws estimated for the glass/Ag/GO/Au structure by ellipsometry characterization seemed to confirm the morphological behavior observed with SEM measurements . The gold thin film adjusted elastically on the GO/Ag /glass sample, without modifying its overall optical behavior, whereas the interface GO/Ag was more complex. Additionally, calculations based on effective medium theory (EMT) highlighted the potential of Ag/GO structures in multilayer hyperbolic metamaterials for photonic applications.

Meeting the demands of modern high-voltage transmission line applications requires novel functional coatings that minimize corona discharge losses while providing sufficiently low ice adhesion and adequate corrosion protection. This work presents comprehensive results from an extensive study of superhydrophobic (SHC), superhydrophilic (SPhil), hydrophilic (Phil), and slippery liquid-infused porous surfaces (SLIPSs) under alternating current corona discharge. Our experiments confirm that coatings at both extremes of the wettability spectrum—water-repelling SHC and water-attracting SPhil—can reduce corona discharge currents by two to four times under adverse weather conditions, whereas SLIPS coatings, despite their water repellency, may actually increase corona currents in rainy conditions.

Furthermore, we observed distinct differences in long-term coating stability under harsh corona discharge conditions, including ozone exposure, UV radiation, and ion bombardment. SLIPS coatings rapidly degrade due to depletion of the lubricating layer, while SHC coatings exhibit very slow, yet discernible deterioration. In contrast, Phil and SPhil coatings tend to improve their corona-protective properties upon exposure to corona discharge. Among these options, hydrophilic organosilane coatings offer the best overall balance: they significantly reduce corona power losses, maintain ice adhesion levels comparable to bare wires, and achieve a threefold reduction in corrosion currents. Meanwhile, superhydrophilic coatings demonstrate reduced corona discharge but suffer from increased ice adhesion and corrosion rates.

These findings underscore the importance of selecting and optimizing coatings to suit specific climatic conditions. In regions with significant icing, durable superhydrophobic coatings hold promise, provided further work is done to enhance their longevity. In warmer, humid climates, hydrophilic and superhydrophilic coatings are more suitable. Overall, our results highlight how tailoring surface wettability can mitigate corona discharge and other environmental impacts, paving the way for improved performance and reliability of high-voltage transmission lines.

Introduction. The co-electrolysis of nitrate and CO₂ can contribute to urea production with low carbon-oxide emission rate, and at the same time can reduce NO₃^- to extremely low permissible concentrations. The synthesis of thin-layer nanoelectrocatalysts containing transition-metal nanoparticles is a promising venture. The study proposes the use of precipitated electrocatalysts from base metals. Such a method makes it possible to obtain an electrocatalyst selective to the reduction reaction of CO₂ or NO₃^-, and their joint reduction product is urea. The electrocatalyst coating should firmly bind C-N, and can proceed with the formation of intermediate compounds (such as *CONH₂) and others.

Experimental. The materials for the electrocatalyst were synthesized by the authors, and characterized using the methods of SEM, XPS, and DRS. The electrochemical methods of voltammetry, chronoamperometry, electrochemical double-layer capacity, and electrochemical impedance spectroscopy were used in this work.

Results and Discussion. In this study, a selective thin-layer electrocatalyst is to be synthesized and used for the reaction of CO₂ and NO₃^- binding and their conversion to urea. The reaction will be carried out using electrochemical reduction under galvanostatic and potentiostatic conditions. As a result, the rate of synthesis of the target product will be determined and the Faraday efficiency of the process will be calculated. The unique electronic structure of transition metals allows them to be active catalysts in the co-reduction reaction of nitrate and carbon dioxide. The choice of metal or different combinations of components in bimetallic catalysts, as well as exploring the conditions of electrochemical synthesis, may allow us to improve the kinetics of the process and increase the selectivity of the process.

Acknowledgment. The authors acknowledge support from Lomonosov Moscow State University Program of Development for providing access to the EIS facilities. The authors express their acknowledgements to the Russian National Research Project No. AAAAA-A21–122040600057–3.

There is significant interest in the development and application of doped metal oxides and metal chalcogenide thin films due to their versatile properties and potential for integration into advanced technologies. These materials find applications in various domains, including transparent conducting oxides (TCOs) for optoelectronic devices, thermographic phosphors for temperature sensing, and buffer layers in solar photovoltaic (PV) cells, among others.

This study focuses on three promising thin film deposition techniques—Metal Organic Chemical Vapor Deposition (MOCVD), Sol-Gel, and Spray Pyrolysis—each tailored to fabricate specific doped thin films with desirable properties. Aluminum-doped zinc oxide (Al:ZnO) thin films were synthesized using MOCVD to achieve high electrical conductivity and optical transparency, essential for TCO applications. Europium-doped titanium dioxide (Eu:TiO₂) films, prepared via the Sol-Gel method, were optimized for luminescent and photocatalytic functionalities, making them suitable for applications in sensors and environmental remediation. Finally, tin disulfide (SnS₂) thin films, deposited through Spray Pyrolysis, were developed for their potential as an efficient light-harvesting material in photovoltaic devices.

The presentation highlights the synthesis processes, characterization techniques, and the resulting structural, optical, and electronic properties of these thin films, emphasizing their suitability for specific applications. These advancements underscore the importance of tailored deposition methods in the research and development of high-performance materials for next-generation technologies

Chiral photonics research is increasingly centered on developing thin films that manipulate optical properties through enantioselective methods, offering promising applications in optical signal processing, sensing, and molecular spintronics. These thin films provide unique opportunities for controlling linear and nonlinear optical behavior, making them ideal candidates for advanced photonic devices and coatings. In this study, we focus on the development of thin spin-coated chiral polymer films, synthesized through the copolymerization of chiral fluorene monomers with thiophene comonomers via the Suzuki polycondensation method. By modulating the conjugation units within the monomer, we precisely control the chiroptical properties of the thin films, enabling their use in various photonic applications. We employ several strategies to enhance the optical activity of these films, including the incorporation of supramolecular softeners (PEM-OH) and plasmonic doping during the film deposition process. These approaches facilitate spatiotemporal control over the chiroptical properties via in situ photopolymerization, demonstrating significant enhancements in the optical performance of the thin films. Furthermore, we achieve substantial improvements in magneto-optic (MO) properties in these thin films, with a high Verdet constant, surpassing the performance of existing MO materials. The spin-coated chiral polymer films demonstrate great potential for applications such as optical isolation, weak magnetic field mapping, and advanced coating technologies for metamaterial design. The ability to manipulate the electric and magnetic dipole coupling in these thin films opens new possibilities for controlling MO effects across a wide range of wavelengths, positioning these materials at the forefront of chiral photonics and optoelectronics

The goal of bio-based, sustainable, and green coating formulations is to replace conventional petrochemical-based materials, thereby reducing VOC emissions and dependence on non-renewable resources. The present research focuses on the synthesis and characterization of UV-curable, bio-based, sustainable, green coating formulations derived from plant oils and other sustainable feedstock. This system uses bio-based epoxidized soybean oil (ESBO) and itaconic acid as major renewable precursors. We prepared the resin by ring-opening of ESBO with polyol, involving an etherification reaction and finally esterification with a bio-based acid. The progress of the reaction was monitored by the oxirane oxygen content (OOC) and acid value. Several formulations were attempted by varying the ratio of oil and polyol. The resin thus prepared was used for coating formulations by varying percentages of the photoinitiator and reactive diluents. Thus, the prepared formulations were applied to the substrate and cured by exposure to the UV radiation source.

The cured films on the substrate were investigated for mechanical and chemical properties. Properties such as scratch hardness, pencil hardness, adhesion, gel content, solvent rub resistance, and gloss were studied. The chemical changes during the reaction and after curing were confirmed by FTIR. The increased renewable content (above 70%) and non-volatile matter in the coating formulations demonstrate their sustainability and green nature. The mechanical properties were observed to be on par with the traditional petroleum-based coatings, showing their enormous potential in UV-curable coating applications. This work demonstrates that incorporating bio-based components into UV-curable systems can produce high-performance, sustainable coatings that contribute to environmental conservation and resource efficiency. This advancement contributes to the development of greener coating technologies that align with global sustainability goals.

Single-walled carbon nanotubes (SWCNTs) with different properties are prepared for applications. The control of the structure of the SWCNTs is important. The analysis of the structure of the pristine and functionalized SWCNTs is needed for biosensor applications. The investigation of the characteristics of the crystal structure of the substances encapsulated inside SWCNTs opens ways to revealing the parameters of the structure. The diameters of the SWCNTs are chosen precisely, and crystal structures are modified for particular applications. It becomes possible to tailor the crystal structure of the compounds in the SWCNTs with different metallicities, diameters, and numbers of walls. The aim of this work is the investigation of the crystal structure in the SWCNTs and modified SWCNTs, and the analysis of the electronic features in modified SWCNTs. The crystal structure of silver chloride inside the SWCNTs with a metallicity-mixed and semiconducting conductivity type was investigated. New one-dimensional structures were obtained inside the SWCNTs with a diameter of 1.4 nm, as revealed by scanning transmission electron microscopy (STEM). The analysis of the electronic features of filled SWCNTs gives information on doping. Raman spectroscopy showed modified electronic properties of the filled metallicity-mixed and semiconducting SWCNTs. Doping was observed in the filled SWCNTs. These data are useful for biosensor applications of filled SWCNTs.

This study investigates the use of chitosan-alkyl polyglucoside (APG) mixtures as environmentally friendly ingredients in 2-in-1 shampoo formulations. For this purpose, experiments were performed by varying the surfactant concentration and ionic strength at a fixed chitosan concentration. The results show that chitosan–APG mixtures exhibit a phase diagram strongly influenced by APG concentration. At constant chitosan concentration, two different types of regions emerge: one characterized by the formation of transparent mixtures at low and high surfactant concentrations, and another with turbid mixtures at intermediate concentrations where no macroscopic phase separation was observed. These turbid mixtures result from a coacervation process that is critical for the formation of conditioning deposits. The ionic strength affects the phase transition, causing shifts from transparent mixtures to coacervates and back at lower APG concentrations, although the overall phase behavior remained qualitatively similar. Chitosan–APG mixtures promote the formation of conditioning deposits via coacervate deposition. When the system reached the coacervation region, deposition increased significantly regardless of ionic strength. This finding is critical to the development of effective hair care products and demonstrates the potential of these mixtures to provide conditioning benefits comparable to traditional formulations. In summary, this research enhances the development of sustainable and natural cosmetics while addressing key scientific questions about biopolymer behavior under varying conditions.