Surfaces

17 pages, 2685 KiB

Open AccessArticle

Co-Effect of pH Control Agent and pH Value on the Physical Properties of ZnO Thin Films Obtained by Chemical Bath Deposition for Potential Application in Dye-Sensitized Solar Cells

by Alphonse Déssoudji Gboglo, Mazabalo Baneto, Komlan Segbéya Gadedjisso-Tossou, Ognanmi Ako, Ayayi Claude Ahyi, Muthiah Haris, Muthusamy Senthilkumar, Kekeli N’konou, Bruno Grandidier, Katawoura Beltako, Komi Apélété Amou and Milohum Mikesokpo Dzagli

Surfaces 2025, 8(3), 46; https://doi.org/10.3390/surfaces8030046 - 1 Jul 2025

Abstract

This study presents the influence of pH control agents and pH value on the physical properties of ZnO thin films obtained by chemical bath deposition. ZnO thin films were synthesized on glass substrates using precursor solutions of different pHs prepared from two bases: [...] Read more.

This study presents the influence of pH control agents and pH value on the physical properties of ZnO thin films obtained by chemical bath deposition. ZnO thin films were synthesized on glass substrates using precursor solutions of different pHs prepared from two bases: sodium hydroxide (NaOH) and ammonia (NH₃). The effect of pH values on the morphological, structural, and optical properties of ZnO thin films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV–Visible spectroscopy. XRD results showed that all the synthesized ZnO thin films are polycrystalline and crystallize in a hexagonal wurtzite structure. The crystallite size, calculated using the Debye–Scherrer formula, varied from 10.50 nm to 11.69 nm for ZnO thin films obtained with NH₃ and from 20.79 nm to 27.76 nm for those obtained with NaOH. FTIR analysis confirmed the presence of functional groups. SEM images indicated that not only the base but also the pH affects the morphology of the films, giving rise to different granular shapes. Overall, the ZnO thin films obtained with NaOH looked more mesoporous compared to those obtained with NH₃. Optical characterization results showed that whatever the base used, the pH of the precursor solution affected the ZnO thin film transmittance. Films synthesized with NH₃ exhibited the best transmittance (80%) at pH 8.5, while the best transmittance (81%) of films synthesized with NaOH was obtained at pH 8 in the visible region. Based on optical and morphological properties, ZnO films obtained from NH₃ at pH 8.5 are found to be more suitable as photoanodes in dye-sensitized solar cells. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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13 pages, 6820 KiB

Open AccessArticle

An Exploration of SPS Fabrication and the Sliding Wear Properties of γ-TiAl-Ag Self-Lubrication Materials

by Na Xiao, Chenglong Yang, Shengfei Zhou, Yuliang Yin, Dian Zhao, Yulong Shi and Kang Yang

Surfaces 2025, 8(3), 45; https://doi.org/10.3390/surfaces8030045 - 30 Jun 2025

Abstract

To promote the optimization of the anti-friction and anti-wear behavior of lightweight TiAl alloys, γ-TiAl-10 wt.% Ag self-lubricating composites were fabricated, and their mechanical and tribological properties were tested. The results showed that the silver in TiAl-10 wt.% Ag slightly reduced its mechanical [...] Read more.

To promote the optimization of the anti-friction and anti-wear behavior of lightweight TiAl alloys, γ-TiAl-10 wt.% Ag self-lubricating composites were fabricated, and their mechanical and tribological properties were tested. The results showed that the silver in TiAl-10 wt.% Ag slightly reduced its mechanical properties compared with those of pure TiAl alloys. A silver-enriched lubrication film formed on a wear scar, which was helpful in improving the friction and wear behavior. It was found that a large amount of silver gathered at a wear scar, gradually spread out under the action of the sliding friction force, and then increased the silver distribution areas on the wear scar, leading to the good formation of a silver-rich film. Furthermore, an identification model was established to calculate the specific area η of the silver film. A quantitative relationship indicated that an increase in the Ag distribution area improved the tribological behavior of γ-TiAl-10 wt.% Ag. When the specific area η of a silver-rich film was maintained at 44–51%, the small friction coefficient (almost 0.28) and wear rate (about 2.25 × 10⁻⁴ mm³·N⁻¹·m⁻¹) were well stabilized. This provides a new research method to improve the tribological performance of TiAl-Ag samples. Full article

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10 pages, 1777 KiB

Open AccessCommunication

Glucose-Mediated Microstructure Refinement of Electroless Silver Coatings on Atomized Fe Particles

by Dehou Song, Tiebao Wang, Lichen Zhao, Pan Gong and Xin Wang

Surfaces 2025, 8(3), 44; https://doi.org/10.3390/surfaces8030044 - 25 Jun 2025

Abstract

Electroless silver (Ag) plating has emerged as a simple yet effective surface modification technique, garnering significant attention in consumer electronics and composite materials. This study systematically investigates the influence of glucose dosage on the microstructural refinement of Ag coatings deposited from silver–ammonia solutions [...] Read more.

Electroless silver (Ag) plating has emerged as a simple yet effective surface modification technique, garnering significant attention in consumer electronics and composite materials. This study systematically investigates the influence of glucose dosage on the microstructural refinement of Ag coatings deposited from silver–ammonia solutions onto iron (Fe) particles while also evaluating the oxidation resistance of Ag-plated particles through thermogravimetric analysis. Optimal results were achieved at a silver nitrate concentration of 0.02 mol/L and a glucose concentration of 0.05 mol/L, producing Fe particles with a uniform and dense silver coating featuring an average Ag grain size of 76 nm. The moderate excess glucose played a dual role: facilitating Ag⁺ ion reduction while simultaneously inhibiting the growth of Ag atomic clusters, thereby ensuring microstructural refinement of the silver layer. Notably, the Ag-plated particles demonstrated superior oxidation resistance compared to their uncoated counterparts. These findings highlight the significance of fine-grained electroless Ag plating in developing high-temperature conductive metal particles and optimizing interfacial structures in composite materials. Full article

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15 pages, 11303 KiB

Open AccessArticle

Hierarchical Manganese-Doped Nickel–Cobalt Oxide Electrodes with Graphene for Use as High-Energy-Density Supercapacitors

by Kuan-Ching Lee, Guan-Ting Pan, Thomas Chung-Kuang Yang, Po-Cheng Shen, Kuan Lun Pan, Timm Joyce Tiong, Aleksandar N. Nikoloski and Chao-Ming Huang

Surfaces 2025, 8(3), 43; https://doi.org/10.3390/surfaces8030043 - 25 Jun 2025

Abstract

Thin films of manganese–nickel–cobalt oxide with graphene (G@MNCO) were deposited on copper foam using electrochemical deposition. NiCo₂O₄ is the main phase in these films. As the proportion of graphene in the precursor solution increases, the oxygen vacancies in the samples [...] Read more.

Thin films of manganese–nickel–cobalt oxide with graphene (G@MNCO) were deposited on copper foam using electrochemical deposition. NiCo₂O₄ is the main phase in these films. As the proportion of graphene in the precursor solution increases, the oxygen vacancies in the samples also increase. The microstructure of these samples evolves into hierarchical vertical flake structures. Cyclic voltammetry measurements conducted within the potential range of 0–1.2 V reveal that the electrode with the highest graphene content achieves the highest specific capacitance, approximately 475 F/g. Furthermore, it exhibits excellent cycling durability, maintaining 95.0% of its initial capacitance after 10,000 cycles. The superior electrochemical performance of the graphene-enhanced, manganese-doped nickel–cobalt oxide electrode is attributed to the synergistic contributions of the hierarchical G@MNCO structure, the three-dimensional Cu foam current collector, and the binder-free fabrication process. These features promote quicker electrolyte ion diffusion into the electrode material and ensure robust adhesion of the active materials to the current collector. Full article

(This article belongs to the Special Issue Surface Science in Electrochemical Energy Storage)

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12 pages, 2254 KiB

Open AccessArticle

Hydrophobic Boron Nitride Nanoflower Coatings on Mild Steel Surfaces

by Aamir Nadeem, Muhammad Faheem Maqsood, Mohsin Ali Raza, Syed Muhammad Zain Mehdi and Shahbaz Ahmad

Surfaces 2025, 8(3), 42; https://doi.org/10.3390/surfaces8030042 - 25 Jun 2025

Abstract

Growing demand for chemically resistant, thermally stable, and anti-icing coatings has intensified interest in boron nitride (BN)-based materials and surface coatings. In this study, BN coatings were developed on mild steel (MS) via chemical vapour deposition (CVD) at 1200 °C for 15, 30, [...] Read more.

Growing demand for chemically resistant, thermally stable, and anti-icing coatings has intensified interest in boron nitride (BN)-based materials and surface coatings. In this study, BN coatings were developed on mild steel (MS) via chemical vapour deposition (CVD) at 1200 °C for 15, 30, and 60 min, and their structural, surface, and water-repellent characteristics were evaluated. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy confirmed the successful formation of BN, while water contact angle measurements indicated high hydrophobicity, demonstrating excellent barrier properties. Scanning electron microscopy (SEM) revealed morphological evolution from flower- and needle-like BN structures in the sample placed in the CVD furnace for 15 min to dense, coral-like, and tubular networks in the samples placed for 30 and 60 min. These findings highlight that BN coatings, particularly the one obtained after 30 min of deposition, have a high hydrophobic character following the Cassie–Baxter model and can be used for corrosion resistance and anti-icing on MS, making them ideal for industrial applications requiring long-lasting protection. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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18 pages, 10483 KiB

Open AccessArticle

The Effect of Low-Temperature Plasma Treatment on the Adhesive Bonding Performance of CF/PEKK Surfaces

by Liwei Wen, Zhentao Dong and Ruozhou Wang

Surfaces 2025, 8(3), 41; https://doi.org/10.3390/surfaces8030041 - 20 Jun 2025

Abstract

Polyaryletherketone (PAEK) polymers inherently exhibit low surface activity, leading to poor adhesive bonding performance when using epoxy-based adhesives. In this study, low-temperature plasma surface modification was conducted on carbon fiber-reinforced polyetherketone ketone (CF/PEKK) composites to investigate the influence of plasma treatment parameters on [...] Read more.

Polyaryletherketone (PAEK) polymers inherently exhibit low surface activity, leading to poor adhesive bonding performance when using epoxy-based adhesives. In this study, low-temperature plasma surface modification was conducted on carbon fiber-reinforced polyetherketone ketone (CF/PEKK) composites to investigate the influence of plasma treatment parameters on their lap shear strength. Surface characterization was systematically performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angle analysis to evaluate morphological, chemical, and wettability changes induced via plasma treatment. The results demonstrated a significant enhancement in lap shear strength after plasma treatment. Optimal bonding performance was achieved at a treatment speed of 10 mm/s and a nozzle-to-substrate distance of 5 mm, yielding a maximum shear strength of 28.28 MPa, a 238% improvement compared to the untreated control. Notably, the failure mode transitioned from interfacial fracture in the untreated sample to a mixed-mode failure dominated by cohesive failure of the adhesive and substrate. Plasma treatment substantially reduced the contact angle of CF/PEKK, indicating improved surface wettability. SEM micrographs revealed an increased micro-porous texture on the treated surface, which enhanced mechanical interlocking between the composite and adhesive. XPS analysis confirmed compositional alterations, specifically elevated oxygen-containing functional groups on the plasma-treated surface. These modifications facilitated stronger chemical bonding between CF/PEKK and the epoxy resin, thereby validating the efficacy of plasma treatment in optimizing surface chemical activity and adhesion performance. Full article

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17 pages, 6997 KiB

Open AccessArticle

Wettability’s Challenge to High-Voltage Insulators: Polyurethane as Preventive Coating

by Touqeer Ahmad Raza, Muhammad Kamran, Syed Ahtisham Mehmood Shah and Muhammad Mehran Bashir

Surfaces 2025, 8(2), 40; https://doi.org/10.3390/surfaces8020040 - 19 Jun 2025

Abstract

The failure of a porcelain insulator on a transmission line is a crucial cause of power supply interruptions, leading to poor reliability and revenue loss. The insulator’s performance is adversely affected by environmental contaminants, and wettability intensifies this adverse effect by developing a [...] Read more.

The failure of a porcelain insulator on a transmission line is a crucial cause of power supply interruptions, leading to poor reliability and revenue loss. The insulator’s performance is adversely affected by environmental contaminants, and wettability intensifies this adverse effect by developing a conductive path along the insulator’s surface, leading to premature flashover and insulator failure. This work aims to analyze the response of the electric field distribution and current density using the finite element method (FEM) under different wettability conditions. Discrete water droplets were placed along the surface, and the contact angle was varied to represent different levels of surface hydrophobicity. Abrupt rises and spikes were observed on the plots for the electric field and current density distribution, indicating distortion; however, the distortion kept on decreasing with the increase in the contact angle. Overall, the average stress followed a declining pattern, where the values of the electric field were reduced from 2.588 to 2.412 kV/cm, and current the density was reduced from 0.187 to 0.068 nA/cm² for an increase in the contact angle from 60° to 140°. Simulation results advocate for hydrophobic insulator surfaces. Therefore, a proper coating is necessary to enrich hydrophobicity and mitigate the adversity of wettability. Polyurethane, due to its excellent hydrophobic and insulating properties, offers a potential coating. Flashover voltage tests have been performed for the coated insulator under dry and wet conditions, where the flashover voltage improved from 79.14 kV to 82.04 kV and 48.4 kV to 53.8 kV, respectively, which supports the simulations’ outcomes. Full article

(This article belongs to the Special Issue Surface Science: Polymer Thin Films, Coatings and Adhesives)

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14 pages, 1673 KiB

Open AccessArticle

Drying and Film Formation Processes of Graphene Oxide Suspension on Nonwoven Fibrous Membranes with Varying Wettability

by Zeman Liu, Jiaxing Fan, Jian Xue and Fei Guo

Surfaces 2025, 8(2), 39; https://doi.org/10.3390/surfaces8020039 - 18 Jun 2025

Abstract

Graphene oxide (GO) films have attracted significant attention due to their potential in separation and filtration applications. Based on their unique lamellar structure and ultrathin nature, GO films are difficult to maintain in a free-standing form and typically require substrate support. Consequently, understanding [...] Read more.

Graphene oxide (GO) films have attracted significant attention due to their potential in separation and filtration applications. Based on their unique lamellar structure and ultrathin nature, GO films are difficult to maintain in a free-standing form and typically require substrate support. Consequently, understanding their film formation behavior and mechanisms on substrates is of paramount importance. This work employs commonly used nonwoven fibrous membranes as substrates and guided by the coffee-ring theory, systematically investigates the film formation behaviors, film morphology, and underlying mechanisms of GO films on fibrous membranes with varying wettability. Fibrous membranes with different wetting properties—hydrophilic, hydrophobic, and superhydrophobic—were prepared via electrospinning and initiated chemical vapor deposition (iCVD) surface modification techniques. The spreading behaviors, deposition dynamics, capillary effects, and evaporation-induced film formation mechanisms of GO suspensions on these substrates were thoroughly examined. The results showed that GO formed belt-like, ring-like, and circular patterns on the three fibrous membranes, respectively. GO films encapsulated more than the upper half, approximately the upper half, and the top portion of fibers, respectively. Pronounced wrinkling of GO films was observed except for those on the hydrophilic fibrous membrane. This work demonstrates that tuning the wettability of fibrous substrates enables precise control over GO film morphology, including fiber encapsulation, wrinkling, and coverage area. Furthermore, it deepens the understanding of the interactions between 1D nanofibers and 2D GO sheets at low-dimensional scales, laying a foundational basis for the optimized design of membrane engineering. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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13 pages, 3815 KiB

Open AccessArticle

Optimizing Crystalline MoS₂ Growth on Technologically Relevant Platinum Substrates Using Ionized Jet Deposition: Interface Interactions and Structural Insights

by Cristian Tomasi Cebotari, Christos Gatsios, Andrea Pedrielli, Lucia Nasi, Francesca Rossi, Andrea Chiappini, Riccardo Ceccato, Roberto Verucchi, Marco V. Nardi and Melanie Timpel

Surfaces 2025, 8(2), 38; https://doi.org/10.3390/surfaces8020038 - 6 Jun 2025

Abstract

Transition metal dichalcogenides, especially molybdenum disulfide (MoS₂), exhibit exceptional properties that make them suitable for a wide range of applications. However, the interaction between MoS₂ and technologically relevant substrates, such as platinum (Pt) electrodes, can significantly influence its properties. This [...] Read more.

Transition metal dichalcogenides, especially molybdenum disulfide (MoS₂), exhibit exceptional properties that make them suitable for a wide range of applications. However, the interaction between MoS₂ and technologically relevant substrates, such as platinum (Pt) electrodes, can significantly influence its properties. This study investigates the growth and properties of MoS₂ thin films on Pt substrates using ionized jet deposition, a versatile, low-cost vacuum deposition technique. We explore the effects of the roughness of Pt substrates and self-heating during deposition on the chemical composition, structure, and strain of MoS₂ films. By optimizing the deposition system to achieve crystalline MoS₂ at room temperature, we compare as-deposited and annealed films. The results reveal that as-deposited MoS₂ films are initially amorphous and conform to the Pt substrate roughness, but crystalline growth is reached when the sample holder is sufficiently heated by the plasma. Further post-annealing at 270 °C enhances crystallinity and reduces sulfur-related defects. We also identify a change in the MoS₂–Pt interface properties, with a reduction in Pt–S interactions after annealing. Our findings contribute to the understanding of MoS₂ growth on Pt and provide insights for optimizing MoS₂-based devices in catalysis and electronics. Full article

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17 pages, 3084 KiB

Open AccessArticle

Microstructural Evolution and Domain Engineering in Porous PZT Thin Films

by Evgeny Zhemerov, Arseniy Buryakov, Dmitry Seregin and Maxim Ivanov

Surfaces 2025, 8(2), 37; https://doi.org/10.3390/surfaces8020037 - 1 Jun 2025

Abstract

Porous PZT films offer significant potential due to tunable electromechanical properties, yet the polarization behavior remains insufficiently understood because of discontinuous morphology and domain structures. In this work, we study the impact of porosity on the spontaneous polarization and electromechanical response of PZT [...] Read more.

Porous PZT films offer significant potential due to tunable electromechanical properties, yet the polarization behavior remains insufficiently understood because of discontinuous morphology and domain structures. In this work, we study the impact of porosity on the spontaneous polarization and electromechanical response of PZT thin films fabricated using a multilayer spin-coating technique with various concentrations (0–14%) of polyvinylpyrrolidone (PVP) as a porogen. Atomic force microscopy (AFM) and piezoresponse force microscopy (PFM) were employed to analyze the local topography, domain distribution, and polarization behavior of the films. The results indicate that increasing porosity leads to substantial changes in grain morphology, dielectric permittivity, and polarization response. Films with higher porosity exhibit a more fragmented polarization distribution and reduced piezoresponse, while certain orientations demonstrate enhanced domain mobility. Despite the decrease in overall polarization, the local coercive field remains relatively stable, suggesting structural stability during the local polarization switching. The findings highlight the crucial role of grain boundaries and local charge redistribution in determining local polarization behavior. Full article

(This article belongs to the Collection Featured Articles for Surfaces)

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15 pages, 4691 KiB

Open AccessArticle

Comparison of Continuous and Pulsed Low-Power DC Sputtered Ti Thin Films Deposited at Room Temperature

by Anna Maria Reider, Ariane Kronthaler, Fabio Zappa, Alexander Menzel, Felix Laimer and Paul Scheier

Surfaces 2025, 8(2), 36; https://doi.org/10.3390/surfaces8020036 - 31 May 2025

Abstract

Titanium thin films with thicknesses of up to 105 nm were deposited on borosilicate glass implementing low-power continuous (25 W) and pulsed (85 W, with an ultra-low duty cycle) DC magnetron sputtering. The characteristics of the resulting films were studied via atomic force [...] Read more.

Titanium thin films with thicknesses of up to 105 nm were deposited on borosilicate glass implementing low-power continuous (25 W) and pulsed (85 W, with an ultra-low duty cycle) DC magnetron sputtering. The characteristics of the resulting films were studied via atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), VIS spectroscopy, and four-point-probe measurements. Both deposition modes yield films with low surface roughness, and AFM analysis showed no topographical features indicative of columnar-and-void structures. The films exhibited high optical reflectivity and stable transmittance and reflectance across the visible spectrum. The electric resistivity could be measured even at single nanometer thickness, emphasizing the metallic character of the films and approaching the bulk titanium value at higher film thicknesses. The low power regime of magnetron sputter deposition not only offers the possibility of studying the development of physical characteristics during the growth of ultra-thin films but also provides the advantage of extremely low heat development and no evident mechanical stress on the substrate during the coating process. These results outline a path for low-power DC sputtering as a reliable approach for studying the evolution of functional properties in ultra-thin films and for the gentle fabrication of coatings where thermal stress must be avoided, making the method compatible with temperature-sensitive applications. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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16 pages, 48638 KiB

Open AccessArticle

Epitaxial Growth of Ni-Mn-Ga on Al₂O₃(

11 \bar{2} 0

) Single-Crystal Substrates by Pulsed Laser Deposition

by Manuel G. Pinedo-Cuba, José M. Caicedo-Roque, Jessica Padilla-Pantoja, Justiniano Quispe-Marcatoma, Carlos V. Landauro, Víctor A. Peña-Rodríguez and José Santiso

Surfaces 2025, 8(2), 35; https://doi.org/10.3390/surfaces8020035 - 30 May 2025

Abstract

Magnetic shape memory alloys have attracted considerable attention due to their multifunctional properties. Among these materials, Ni-Mn-Ga alloys are distinguished by their ability to achieve up to 10% strain when exposed to a magnetic field, a characteristic predominantly observed in single-crystal samples. Consequently, [...] Read more.

Magnetic shape memory alloys have attracted considerable attention due to their multifunctional properties. Among these materials, Ni-Mn-Ga alloys are distinguished by their ability to achieve up to 10% strain when exposed to a magnetic field, a characteristic predominantly observed in single-crystal samples. Consequently, it is essential to develop nanomaterials with a crystal structure closely resembling that of a single crystal. In this study, an epitaxial Ni-Mn-Ga thin film was fabricated using Pulsed Laser Deposition on an Al₂O₃

(11 \bar{2} 0)

single-crystal substrate. The crystal structure was characterised through X-ray diffraction methodologies, such as symmetrical

2 θ - ω

scans, pole figures, and reciprocal space maps. The results indicated that the sample was mainly in a slightly distorted cubic austenite phase, and some incipient martensite phase also appeared. A detailed microstructural analysis, performed by transmission electron microscopy, confirmed that certain regions of the sample exhibited an incipient transformation to the martensite phase. Regions closer to the substrate retained the austenite phase, suggesting that the constraint imposed by the substrate inhibits the phase transition. These results indicate that it is possible to grow high crystalline quality thin films of Ni-Mn-Ga by Pulsed Laser Deposition. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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17 pages, 3451 KiB

Open AccessArticle

TPA and PET Photo-Degradation by Heterogeneous Catalysis Using a (Al₂O₃)_0.75TiO₂ Coating

by Mónica A. Camacho-González, Alberto Hernández-Reyes, Aristeo Garrido-Hernández, Octavio Olivares-Xometl, Natalya V. Likhanova and Irina V. Lijanova

Surfaces 2025, 8(2), 34; https://doi.org/10.3390/surfaces8020034 - 21 May 2025

Cited by 1

Abstract

The combination of the catalytic properties of Al₂O_3/TiO₂ formed an efficient system to degrade the ubiquitous pollutants TPA and PET. The coating (Al₂O₃)_0.75TiO₂ was characterized by X-ray diffraction. Stainless steel disks [...] Read more.

The combination of the catalytic properties of Al₂O_3/TiO₂ formed an efficient system to degrade the ubiquitous pollutants TPA and PET. The coating (Al₂O₃)_0.75TiO₂ was characterized by X-ray diffraction. Stainless steel disks with photo-catalyst coating were placed transversely in a 3.0 L vertical glass reactor with ascending airflow for supplying oxygen to the reaction medium and visible light lamps for photo-activation. The analysis of the coating homogeneity, morphology and particle size distribution of the TiO₂ coatings and (Al₂O₃)_0.75TiO₂ system were confirmed by SEM. Optical properties and band-gap energy were calculated by using the Tauc equation. UV–Vis spectrophotometry (UV–Vis) and chemical oxygen demand (COD) were the quantitative techniques to measure the reduction in the initial TPA and PET concentrations. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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11 pages, 3385 KiB

Open AccessArticle

Functional Polyacrylate Textile Coatings with N,N-Diethyl-3-methylbenzamide (DEET) Immobilized on Zirconia, Alumina and Silica Sorbents

by Sergei Zverev, Sergei Andreev, Ekaterina Anosova, Varvara Morenova, Maria Rakitina and Vladimir Vinokurov

Surfaces 2025, 8(2), 33; https://doi.org/10.3390/surfaces8020033 - 9 May 2025

Abstract

In this study, polymer films based on the inorganic sorbents Al₂O₃, ZrO₂ and SiO₂-phenyl with repellent N,N-diethyl-3-methylbenzamide were prepared and used as functional textile coatings. The high sorption activity of oxides with respect [...] Read more.

In this study, polymer films based on the inorganic sorbents Al₂O₃, ZrO₂ and SiO₂-phenyl with repellent N,N-diethyl-3-methylbenzamide were prepared and used as functional textile coatings. The high sorption activity of oxides with respect to N,N-diethyl-3-methylbenzamide (63–239 mg/g) allows for the use of these compounds as repellent carrier materials, and their mixture with polyacrylates allows for the formation of functional coatings–polymer films. Scanning electron microscopy and Fourier transform infrared spectroscopy results revealed that the inorganic sorbents Al₂O₃, ZrO₂ and SiO₂-phenyl were successfully anchored in the polyacrylate structure, and the FTIR spectra confirmed the presence of repellent molecules. The thermal diffusion parameters of N,N-diethyl-3-methylbenzamide were also calculated via thermogravimetric analysis and high-performance liquid chromatography with diode array detection. The highest thermal diffusion rates and concentrations were observed for the material with Al₂O₃ (up to 148.3∙10⁻⁹ mol at 200 °C), and lower values for ZrO₂ and SiO₂-phenyl (up to 15.2∙10⁻⁹ mol and 34.3∙10⁻⁹ mol at 200 °C, respectively). The heat flux parameter J_f was also calculated according to Onsager’s theory and Fourier’s law. The release of repellent from polymeric materials can be achieved by applying less heat than that required to reach the boiling point of N,N-diethyl-3-methylbenzamide. Full article

(This article belongs to the Special Issue Surface Science: Polymer Thin Films, Coatings and Adhesives)

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12 pages, 3584 KiB

Open AccessArticle

The Coordination of Lanthanide Atoms with Stone–Wales Defects on Graphene: A Cluster DFT Analysis Using ECP Pseudopotentials

by Vladimir A. Basiuk and Elena V. Basiuk

Surfaces 2025, 8(2), 32; https://doi.org/10.3390/surfaces8020032 - 9 May 2025

Abstract

The main goal of the present study was to verify in detail whether the use of a cluster model for Stone–Wales (SW) defect-containing graphene (SWG) to study the adsorption of Ln atoms yields results similar to those previously obtained by employing a periodic [...] Read more.

The main goal of the present study was to verify in detail whether the use of a cluster model for Stone–Wales (SW) defect-containing graphene (SWG) to study the adsorption of Ln atoms yields results similar to those previously obtained by employing a periodic model. We addressed this question by analyzing the optimized geometries of SWG + Ln complexes, their formation energies, and selected electronic parameters (in particular, the frontier orbital energies and atomic charges and spins). Within the frame of density functional theory, we used the computational methodology of the PBE-D2/DNP theoretical level using ECP pseudopotentials. The most important conclusion is that the use of a cluster model gives qualitatively similar results to those of the periodic model. While the corresponding plots of the dihedral angles θ versus the Ln atoms differ considerably, the two models have many common features in the trends of the bonding strength despite the use of two very different theoretical tools, namely periodic (plane waves) versus cluster calculations (localized basis sets). In comparing the results for SW defect-free and SW defect-containing cluster models, it is evident that SW defects serve as much more preferential adsorption sites compared to the conditions in the defect-free graphene model. Full article

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34 pages, 5331 KiB

Open AccessReview

Modelling and Simulation of Surface Diffusion in Heterogeneous Porous Materials

by Sean P. Rigby

Surfaces 2025, 8(2), 31; https://doi.org/10.3390/surfaces8020031 - 7 May 2025

Abstract

The surface diffusion flux is known to dominate mass transport within many amorphous porous materials, used as adsorbents, heterogeneous catalysts, and membranes, employed in many chemical processes. However, while the impact of surface coverage has been widely studied and reviewed, relatively little attention [...] Read more.

The surface diffusion flux is known to dominate mass transport within many amorphous porous materials, used as adsorbents, heterogeneous catalysts, and membranes, employed in many chemical processes. However, while the impact of surface coverage has been widely studied and reviewed, relatively little attention has been paid to the impact of surface geometric and energetic heterogeneity on the surface diffusion rate, which would inform intelligent materials selection. It was, thence, the aim of this work to survey studies of the impact of surface structure on surface diffusion. Since the so-called “maximally realistic” modelling approach is found to be infeasible, due to limitations on the degree of structural characterisation possible for complex disordered surfaces, and the level of detail and length scales it is possible to represent with current computing power, a range of alternative approaches have been adopted. It has been seen that the Galilean idealisation of atomistic models has rendered them sufficiently tractable in order to study the impact of certain surface features, such as traps or ruts, on surface diffusion. Theoretical justifications have been used to develop minimalist models of amorphous surfaces, and mass transport thereon, that do selectively include the key surface parameters, and have, therefore, been successfully empirically validated for a range of different surfaces and adsorbate types. Full article

(This article belongs to the Collection Featured Articles for Surfaces)

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11 pages, 3209 KiB

Open AccessArticle

Induced Effects of Nano-Patterned Substrates on the Electrical and Photo-Electrical Properties of PTB7-Th:ICBA (1:1, wt.%) Bulk-Heterojunction Solar Cells

by Tudor Suteu, Vlad-Andrei Antohe, Stefan Antohe, Ionel Stavarache, Maria Cristina Balasin, Gabriel Socol, Marcela Socol, Oana Rasoga and Sorina Iftimie

Surfaces 2025, 8(2), 30; https://doi.org/10.3390/surfaces8020030 - 1 May 2025

Abstract

In this study, we detailed the fabrication and characterization of photovoltaic structures based on PTB7:ICBA (1:1, wt.%) bulk-heterojunction on optical glass substrates by spin-coating. Some samples were deposited on a flat substrate, and others were placed on a patterned substrate obtained by nano-imprinting [...] Read more.

In this study, we detailed the fabrication and characterization of photovoltaic structures based on PTB7:ICBA (1:1, wt.%) bulk-heterojunction on optical glass substrates by spin-coating. Some samples were deposited on a flat substrate, and others were placed on a patterned substrate obtained by nano-imprinting lithography; the induced effects were analyzed. We demonstrated that using a patterned substrate enhanced the maximum output power, primarily because the short-circuit current density increased. This can be considered a direct consequence of reduced optical reflection and improved optical absorption. The topological parameters evaluated by atomic force microscopy, namely, the root mean square, Skewness, and Kurtosis, had small values of around 2 nm and 1 nm, respectively. This proves that the mixture of a conductive polymer and a fullerene derivative creates a thin film network with a high flatness degree. The samples discussed in this paper were fabricated and characterized in air; we can admit that the results are encouraging, but further optimization is needed. Full article

(This article belongs to the Collection Featured Articles for Surfaces)

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29 pages, 4044 KiB

Open AccessArticle

Adsorption and Thermal Stability of Ionic Liquid Multilayers on ZnO Surfaces

by Zoë Henderson, Jordan Cole, Andrew G. Thomas, Robert G. Jones, Michael Wagstaffe, José Avila, María C. Asensio, Zheshen Li and Karen L. Syres

Surfaces 2025, 8(2), 29; https://doi.org/10.3390/surfaces8020029 - 25 Apr 2025

Abstract

Ionic liquids (ILs) have been explored as a way of improving the performance of ZnO-based optoelectronic devices; however, there are few fundamental studies of the IL/ZnO interface. Here, the adsorption of the IL 1-octyl-3-methylimidazolium tetrafluoroborate [C₈C₁Im][BF₄] on [...] Read more.

Ionic liquids (ILs) have been explored as a way of improving the performance of ZnO-based optoelectronic devices; however, there are few fundamental studies of the IL/ZnO interface. Here, the adsorption of the IL 1-octyl-3-methylimidazolium tetrafluoroborate [C₈C₁Im][BF₄] on ZnO (0001) and ZnO (

10 \bar{1} 0

) has been studied using synchrotron-based soft X-ray photoelectron spectroscopy. The results indicate that [C₈C₁Im][BF₄] is deposited intact on the ZnO (0001) surface; however, there is some dissociation of [BF₄]⁻ anions, resulting in boron atoms attaching to the oxygen atoms in the ZnO surface and forming B₂O₃. In contrast, the deposition of [C₈C₁Im][BF₄] on the ZnO (

10 \bar{1} 0

) surface at −150 °C results in the appearance of more chemical environments in the spectra. We propose that the high temperature of the IL evaporator causes some conversion of [C₈C₁Im][BF₄] to a carbene–borane adduct, resulting in the deposition of both the IL and adduct onto the ZnO surface. The adsorption and desorption of the analogous IL 1-butyl-3-methylimidazolium tetrafluoroborate [C₄C₁Im][BF₄] was investigated on ZnO (0001) using synchrotron-based soft X-ray photoelectron spectroscopy. The results indicate that [C₄C₁Im][BF₄] is deposited largely intact at −150 °C and forms islands when heated to room temperature. When heated to over 80 °C, it begins to react with the ZnO surface and decomposes. This is a much lower temperature than the long-term thermal stability of the pure IL, quoted in the literature as ~400 °C, and of IL on powdered ZnO, quoted in the literature as ~300 °C. This indicates that the ZnO surface may catalyse the thermal decomposition of [C₄C₁Im][BF₄] at lower temperatures. This is likely to have a negative impact on the potential use of ILs in ZnO-based photovoltaic applications, where operating temperatures can routinely reach 80 °C. Full article

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14 pages, 3557 KiB

Open AccessArticle

Marangoni Flow-Driven Self-Assembly of Biomimetic Jellyfish-like Hydrogels for Spatially Controlled Enzyme Catalysis

by Aoxiang Zhang, Huiying Zhou, Yanhui Guo and Yu Fu

Surfaces 2025, 8(2), 28; https://doi.org/10.3390/surfaces8020028 - 22 Apr 2025

Abstract

Enzymatic catalysis has gained significant attention in green chemistry due to its high specificity and efficiency under mild conditions. However, challenges related to enzyme immobilization and spatial control often limit its practical applications. In this work, we report a Marangoni flow-driven strategy to [...] Read more.

Enzymatic catalysis has gained significant attention in green chemistry due to its high specificity and efficiency under mild conditions. However, challenges related to enzyme immobilization and spatial control often limit its practical applications. In this work, we report a Marangoni flow-driven strategy to fabricate a biomimetic jellyfish-like hydrogel with tunable tentacle-like structures. The formation process occurs entirely in an aqueous system without organic solvents or post-treatment, enabling the construction of ultra-thin, free-standing hydrogels through spontaneous interfacial self-assembly. The resulting structure exhibits high surface-area geometry and excellent biocompatibility, providing a versatile platform for localized enzyme loading. This method offers a simple and scalable route for engineering soft materials with complex morphologies, and expands the design space for bioinspired hydrogel systems. Full article

(This article belongs to the Special Issue Surface Science: Polymer Thin Films, Coatings and Adhesives)

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