Journal Description
Surfaces
Surfaces
is an international, peer-reviewed, open access journal on all aspects of surface and interface science published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, Inspec, CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.6 days after submission; acceptance to publication is undertaken in 3.8 days (median values for papers published in this journal in the first half of 2024).
- Journal Rank: CiteScore - Q2 (Materials Science (miscellaneous))
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.3 (2023);
5-Year Impact Factor:
2.6 (2023)
Latest Articles
Synthesis of BiOCl Colloidal Particles by Laser Ablation of Solids in Liquids
Surfaces 2024, 7(4), 864-878; https://doi.org/10.3390/surfaces7040057 (registering DOI) - 15 Oct 2024
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Colloidal bismuth nanoparticles (NPs) were synthesized in sodium chloride (NaCl) solutions at different concentrations using the laser ablation of solids in liquids technique. The obtained materials were characterized using various techniques. The morphology, size, and crystalline phases were determined through scanning electron microscopy
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Colloidal bismuth nanoparticles (NPs) were synthesized in sodium chloride (NaCl) solutions at different concentrations using the laser ablation of solids in liquids technique. The obtained materials were characterized using various techniques. The morphology, size, and crystalline phases were determined through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The optical properties were studied using UV–visible spectroscopy, employing the Tauc method to determine the band gap of the particles. Two types of materials were identified depending on the NaCl concentration: spherical nanoparticles of α-Bi2O3 and the coexistence of α-Bi2O3 and BiOCl particles with irregular morphology. NaCl concentrations higher than 11.6% enable the coexistence of α-Bi2O3 and BiOCl. The photocatalytic response of the colloids was evaluated by the degrading rhodamine B under visible light irradiation. The sample synthesized at a NaCl concentration of 31.6% showed the best photocatalytic activity.
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Open AccessReview
The Usefulness of Infrared Spectroscopy for Elucidating the Degradation Mechanism of Metal Industrial Heritage Coatings
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Ernest Konadu-Yiadom, Ethan Bontrager and Anna Staerz
Surfaces 2024, 7(4), 846-863; https://doi.org/10.3390/surfaces7040056 (registering DOI) - 15 Oct 2024
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As society moves away from heavy industry, large metallic structures will be abandoned. As an alternative to dismantling, these structures could be repurposed. Beyond being a practical solution, the conservation of these structures would serve as an ode to the role of these
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As society moves away from heavy industry, large metallic structures will be abandoned. As an alternative to dismantling, these structures could be repurposed. Beyond being a practical solution, the conservation of these structures would serve as an ode to the role of these industries in shaping modern society. Conservation, however, requires suitable coatings that hinder corrosion long-term while not significantly altering the outward appearance. Traditionally, the stability of coatings has been tested by comparing fresh samples to those aged naturally or in a UV chamber. This method of testing provides no temporal information. Additionally, measuring many different conditions, e.g., UV, humidity, temperature, and pollutants, is tedious. In this review, we highlight how by implementing infrared spectroscopy in different configurations, temporally resolved information about the coating chemistry, the metal–coating interface chemistry, and gas emissions could be gained during degradation. These insights would be essential to enable the intentional design of coatings while simultaneously revealing their environmental impact.
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Open AccessCommunication
Synthesis and Properties of Novel Acrylic Fluorinated Surfactants
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Chao Lin, Jinhua Li, Yejun Qin, Ping Xing and Biao Jiang
Surfaces 2024, 7(4), 838-845; https://doi.org/10.3390/surfaces7040055 (registering DOI) - 14 Oct 2024
Abstract
Branched fluorinated surfactants with creatively introduced acrylate in the hydrophilic group were designed and prepared by adopting perfluoro-2-methyl-2-pentene as the raw substrate. These new compounds showed excellent surface properties, and the surface tension of their aqueous solution at 25 °C could be below
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Branched fluorinated surfactants with creatively introduced acrylate in the hydrophilic group were designed and prepared by adopting perfluoro-2-methyl-2-pentene as the raw substrate. These new compounds showed excellent surface properties, and the surface tension of their aqueous solution at 25 °C could be below 20.00 mN/m at the critical micelle concentration. Compared with similar structures we have synthesized previously, these synthesized compounds exhibit a great improvement with regard to their molecular arrangement at the gas–liquid interface, their polymerizability, and the antibacterial properties of their polymer form, which can provide new ideas in the work to replace perfluorooctane sulfonate/perfluorooctanoic acid.
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(This article belongs to the Special Issue Recent Advances in Catalytic Surfaces and Interfaces)
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Increasing the Wear and Corrosion Resistance of a CP-Ti Surface by Plasma Electrolytic Borocarburizing and Polishing
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Marina A. Volosova, Sergei A. Kusmanov, Ivan V. Tambovskiy, Tatiana L. Mukhacheva, Artem P. Mitrofanov, Igor V. Suminov and Sergey N. Grigoriev
Surfaces 2024, 7(4), 824-837; https://doi.org/10.3390/surfaces7040054 - 7 Oct 2024
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The paper examines the possibility of increasing the wear and corrosion resistance of a CP-Ti surface by duplex plasma electrolytic treatment (borocarburizing and polishing). The structure and composition of diffusion layers, their microhardness, surface morphology and roughness, wear resistance during dry friction and
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The paper examines the possibility of increasing the wear and corrosion resistance of a CP-Ti surface by duplex plasma electrolytic treatment (borocarburizing and polishing). The structure and composition of diffusion layers, their microhardness, surface morphology and roughness, wear resistance during dry friction and corrosion resistance in Ringer’s solution were studied. The formation of a surface-hardened layer up to 200 μm thick with a microhardness of up to 950 HV, including carbides and a solid solution of boron and carbon, is shown. Subsequent polishing makes it possible to reduce surface roughness and remove weak areas of the porous oxide layer, which are formed during high-temperature oxidation in aqueous electrolyte vapor during borocarburizing. Changing the morphology and structural-phase composition of the CP-Ti surface helps reduce weight wear by a factor of three (the mode of frictional interaction changes from microcutting to oxidative wear) and corrosion current density by a factor of four after borocarburizing in a solution of boric acid, glycerin and ammonium chloride at 950 °C for 5 min and subsequent polishing in an ammonium fluoride solution at a voltage of 250 V for 3 min.
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Open AccessArticle
PVD Coatings for Lightweight Bipolar Plates
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Parnia Navabpour, Liam Cooper, Shicai Yang, Jinlong Yin, Kun Zhang, Ahmad El-Kharouf and Hailin Sun
Surfaces 2024, 7(4), 812-823; https://doi.org/10.3390/surfaces7040053 - 2 Oct 2024
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Bipolar plates are one of the main components of proton exchange membrane fuel cells (PEMFCs). Their functions include distributing reactants, supporting the cell, and conducting heat and electricity. They account for a significant proportion of the fuel cell stack’s weight and volume. The
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Bipolar plates are one of the main components of proton exchange membrane fuel cells (PEMFCs). Their functions include distributing reactants, supporting the cell, and conducting heat and electricity. They account for a significant proportion of the fuel cell stack’s weight and volume. The main materials currently used for bipolar plates are graphite and stainless steel. Aluminium has a much lower density than steel and is easier to form than both steel and graphite. Its use, therefore, would allow fuel cells with higher power densities but is hindered due to it being prone to corrosion. This work focused on the development of corrosion-resistant and conductive coatings to address this issue. Carbon coatings with Ti and Cr adhesion layers were deposited on aluminium substrates using closed-field unbalanced magnetron sputtering. These coatings were tested for corrosion properties and performance on the cathode side of a single-cell fuel cell. Coated aluminium samples were also tested for their ability to maintain their corrosion protection after being formed. Coating with a Cr adhesion layer outperformed that with a Ti adhesion layer in both forming and fuel cell tests, demonstrating much lower performance degradation after accelerated stress testing.
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Open AccessArticle
Charged Microdroplets Deposition for Nanostructured-Based Electrode Surface Modification
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Rosaceleste Zumpano, Marco Agostini, Franco Mazzei, Anna Troiani, Chiara Salvitti, Marta Managò, Alessia Di Noi, Andreina Ricci and Federico Pepi
Surfaces 2024, 7(4), 801-811; https://doi.org/10.3390/surfaces7040052 - 1 Oct 2024
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Accelerated synthesis of gold nanoparticles (AuNPs) in charged microdroplets produced by electrospray ionization (ESI) was exploited to modify the surface of graphite screen-printed electrodes (GSPEs). The deposited AuNPs were then functionalized by the charged microdroplets deposition of 6-ferrocenyl-hexanethiol (6Fc-ht) solutions that act as
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Accelerated synthesis of gold nanoparticles (AuNPs) in charged microdroplets produced by electrospray ionization (ESI) was exploited to modify the surface of graphite screen-printed electrodes (GSPEs). The deposited AuNPs were then functionalized by the charged microdroplets deposition of 6-ferrocenyl-hexanethiol (6Fc-ht) solutions that act as reducing and stabilizing agents and provide electrochemical properties for the modified electrodes. The morphology and composition of the AuNPs were characterized by scanning electron microscopy (SEM). Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behavior of the modified electrodes. The results showed that the ESI microdroplets deposition technique produces uniform and well-dispersed AuNPs on GSPE, and optimal conditions for deposition were identified, enhancing GSPE electrocatalytic performance. Further functionalization by ESI microdroplets of AuNPs with 6Fc-ht demonstrated improved redox properties compared with the conventional self-assembled monolayer (SAM) method, highlighting the technique’s potential for the easy and fast functionalization of electrochemical sensors.
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(This article belongs to the Special Issue Recent Advances in Catalytic Surfaces and Interfaces)
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Microplastic-Related Leachate from Recycled Rubber Tiles: The Role of TiO2 Protective Coating
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Paula Benjak, Lucija Radetić, Ivana Presečki, Ivan Brnardić, Nikola Sakač and Ivana Grčić
Surfaces 2024, 7(3), 786-800; https://doi.org/10.3390/surfaces7030051 - 18 Sep 2024
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The extensive global use of rubber results in significant microplastic pollution from the release of tire wear particles and microplastic leachate, impacting the environment, human health, and ecosystems. Waste tires are normally recycled and used for the production of new products, such as
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The extensive global use of rubber results in significant microplastic pollution from the release of tire wear particles and microplastic leachate, impacting the environment, human health, and ecosystems. Waste tires are normally recycled and used for the production of new products, such as rubber tiles. The presented study aims to show the possibility of further decrease in the negative environmental impact of materials based on recycled rubber. This paper presents the modification of rubber tiles with a titanium dioxide (TiO2) coating, focusing on surface integrity, rubber particle wear release, and the consequent environmental impact of leachate release. Both reference and modified rubber tiles were subjected to artificial accelerated aging in a solar simulator for 4, 6, and 8 weeks, followed by an abrasion test. The carbonyl index was calculated from FTIR characterization after each time frame to indicate the degradation of organic compounds and chemical changes caused by UV exposure. A 24 h leaching test with a liquid-to-sample ratio of 1:20 was performed on both rubber tile samples prior to and after 8 weeks of aging along with the aged wear particles for the purpose of the non-target screening of released organic leachate by LC/MS QTOF. The results of carbonyl indices showed that the TiO2 coating contributes to the stabilization of polymer degradation and, to a certain extent, reduces the leaching of organic compounds, such as phthalates. However, the increased wear and release of rubber particles and the subsequent degradation of organic leachates require further in-depth research.
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(This article belongs to the Collection Featured Articles for Surfaces)
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Open AccessArticle
Kelvin Probe Force Microscopy, Current Mapping, and Optical Properties of Hybrid ZnO Nanorods/Ag Nanoparticles
by
Ishaq Musa
Surfaces 2024, 7(3), 770-785; https://doi.org/10.3390/surfaces7030050 - 16 Sep 2024
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The optical characteristics and electrical behavior of zinc oxide nanorods (ZnO-NRs) and silver nanoparticles (Ag-NPs) were investigated using advanced scanning probe microscopy techniques. The study revealed that the ZnO nanorods had a length of about 350 nm, while the Ag nanoparticles were spherical
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The optical characteristics and electrical behavior of zinc oxide nanorods (ZnO-NRs) and silver nanoparticles (Ag-NPs) were investigated using advanced scanning probe microscopy techniques. The study revealed that the ZnO nanorods had a length of about 350 nm, while the Ag nanoparticles were spherical with heights ranging from 5 to 14 nm. Measurements with Kelvin probe force microscopy (KPFM) showed that the work functions of ZnO nanorods were approximately 4.55 eV, higher than that of bulk ZnO, and the work function of Ag nanoparticles ranged from 4.54 to 4.56 eV. The electrical characterization of ZnO nanorods, silver nanoparticles, and their hybrid was also conducted using conductive atomic force microscopy (C-AFM) to determine the local current-voltage (I-V) characteristics, which revealed a characteristic similar to that of a Schottky diode. The current-voltage characteristic curves of ZnO nanorods and Ag nanoparticles both showed an increase in current at around 1 V, and the hybrid ZnONRs/AgNP exhibited an increase in turn-on voltage at around 2.5 volts. This suggested that the presence of Ag nanoparticles enhanced the electrical properties of ZnO nanorods, improving the charge carrier mobility and conduction mechanisms through a Schottky junction. The investigation also explored the optical properties of ZnO-NRs, AgNPs, and their hybrid, revealing absorption bands at 3.11 eV and 3.18 eV for ZnO-NRs and AgNPs, respectively. The hybrid material showed absorption at 3.13 eV, indicating enhanced absorption, and the presence of AgNP affected the optical properties of ZnO-NR, resulting in increased photoluminescence intensity and slightly changes in peak positions.
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(This article belongs to the Special Issue Recent Advances in Catalytic Surfaces and Interfaces)
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Open AccessReview
Supramolecular Chemistry of Polymer-Based Molecular Tweezers: A Minireview
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Bahareh Vafakish and Lee D. Wilson
Surfaces 2024, 7(3), 752-769; https://doi.org/10.3390/surfaces7030049 - 14 Sep 2024
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Polymer-based molecular tweezers have emerged as a prominent research area due to their enhanced ability to form host–guest complexes, driven by advancements in their design and synthesis. The impact of the spacer structure on the tweezers is predominant. They can be rigid, flexible,
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Polymer-based molecular tweezers have emerged as a prominent research area due to their enhanced ability to form host–guest complexes, driven by advancements in their design and synthesis. The impact of the spacer structure on the tweezers is predominant. They can be rigid, flexible, and stimuli-responsive. Herein, a new generation of molecular tweezers is introduced as polymer-based molecular tweezers. The integration of molecular tweezers onto biopolymers has significantly expanded their potential applications, making them promising candidates, especially in drug delivery, owing to their biocompatibility, adaptive structural features, and versatile interaction capabilities. The unique structure of polymer-based molecular tweezers, particularly when integrated with biopolymers, creates a unique nano-environment that enhances their interaction with guest molecules. This minireview focuses on the synthesis and applications of polymer-based molecular tweezers and examines how the incorporation of various spacers affects their binding affinity and specificity. These features highlight the advancement of these polymer-based systems, emphasizing their potential applications, particularly in drug delivery, water treatment technology, and future research opportunities.
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(This article belongs to the Collection Featured Articles for Surfaces)
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Effect of High-Current Pulsed Electron Beam on Microstructure and Surface Properties of Ag-10La0.7Sr0.3CoO3 Composites
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Huanfeng Zhang, Bo Gao, Lei Wang, Wenhuan Shen, Pengshan Lin, Xin Lan and He Liu
Surfaces 2024, 7(3), 739-751; https://doi.org/10.3390/surfaces7030048 - 12 Sep 2024
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This paper investigates the enhancement of the microstructure and properties of Ag-10La0.7Sr0.3CoO3 composites, prepared by powder metallurgy, through the application of high-current pulsed electron beam (HCPEB) irradiation. The X-ray diffraction results showed that the irradiated samples exhibited selective
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This paper investigates the enhancement of the microstructure and properties of Ag-10La0.7Sr0.3CoO3 composites, prepared by powder metallurgy, through the application of high-current pulsed electron beam (HCPEB) irradiation. The X-ray diffraction results showed that the irradiated samples exhibited selective orientations on the surface of their (200) and (311) crystal planes. Microstructural observations revealed a dense remelted layer on the samples’ surface after HCPEB irradiation. The surface hardness of the samples increased after 15 treatments, showing an improvement of 36.76%. This is primarily attributed to fine-grain strengthening, surface remelting, and recrystallization. Further, the electrical conductivity of the samples treated 15 times increased by 74.8% compared to that of the original samples. Electrochemical test results showed that the samples treated 15 times showed the lowest corrosion current density in a 3.5 wt.% NaCl solution. This improved corrosion resistance is attributable to the refinement of the surface’s microstructure and the introduction of residual compressive stress. This study demonstrates the significant impact of HCPEB irradiation on the regulation of the properties of Ag-10La0.7Sr0.3CoO3 composites.
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Open AccessFeature PaperArticle
One-Step Spark Plasma Erosion Processing of Carbon-Coated Sn-Si Nanoparticles for Lithium-Ion Battery Anodes
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Emma Marie Hamilton White, Lisa M. Rueschhoff, Takeshi Kobayashi, Jonathan Z. Bloh, Steve W. Martin and Iver E. Anderson
Surfaces 2024, 7(3), 725-738; https://doi.org/10.3390/surfaces7030047 - 10 Sep 2024
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High density portable energy storage is desirable owing to the energy requirements of portable electronics and electric vehicles. The Li-ion battery’s high energy density could be even further improved through the utilization of alternative materials (instead of carbon) for the anode, such as
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High density portable energy storage is desirable owing to the energy requirements of portable electronics and electric vehicles. The Li-ion battery’s high energy density could be even further improved through the utilization of alternative materials (instead of carbon) for the anode, such as Sn or Si. Nonetheless, the large volume expansion upon lithiation, up to ~300% for Li22Si5, causes pulverization and rapid capacity degradation during cycling. Sn also forms a Li22Sn5 compound with the equivalent stoichiometric Li capacity but with enhanced ductility. Nano-sized Si and Sn have demonstrated distinctive nanoscale properties, facilitating the retention of higher capacities, particularly when coated with carbon, which improves mechanical stability. To date, the methods of synthesizing coated Si, Sn, or Si-Sn alloyed nanoparticles are complicated, costly, and not readily scalable to meet the demands of cost-effective manufacturing. Spark plasma erosion in a hydrocarbon dielectric has been explored as a one-step process to produce Sn-Si alloy nanoparticles coated with a thin carbon film, offering a scalable and cost-effective processing route. The resulting Sn-Si particles exhibited a bi-modal size distribution at ~5 nm and ~500 nm and were carbon-coated, as intended, from the hydrocarbon dielectric breakdown. The spark-eroded nanoparticles were thoroughly characterized using TEM/EDS, XPS, AES, SSNMR, and TGA, and their improved electrochemical performance was assessed through half-cell experiments.
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(This article belongs to the Special Issue Surface Modification and Coating to Improve Properties of Various Materials)
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Open AccessArticle
Wear and Abrasion Resistance of Nitride Coatings on Ceramic Substrates Processed with Fast Argon Atoms
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Sergey N. Grigoriev, Alexander S. Metel, Marina A. Volosova, Enver S. Mustafaev and Yury A. Melnik
Surfaces 2024, 7(3), 714-724; https://doi.org/10.3390/surfaces7030046 - 4 Sep 2024
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The surfaces of ceramic products are replete with numerous defects, such as those that appear during the diamond grinding of sintered SiAlON ceramics. The defective surface layer is the reason for the low effectiveness of TiZrN coatings under abrasive and fretting wear. An
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The surfaces of ceramic products are replete with numerous defects, such as those that appear during the diamond grinding of sintered SiAlON ceramics. The defective surface layer is the reason for the low effectiveness of TiZrN coatings under abrasive and fretting wear. An obvious solution is the removal of an up to 4-µm-thick surface layer containing the defects. It was proposed in the present study to etch the layer with fast argon atoms. At the atom energy of 5 keV and a 0.5 mA/cm2 current density, the ions were converted into fast atoms and the sputtering rate for the SiAlON samples reached 20 μm/h. No defects were observed in the microstructures of coatings deposited after beam treatment for half an hour. The treatment reduced the volumetric abrasive wear by five times. The fretting wear was reduced by three to four times.
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(This article belongs to the Special Issue Surface Modification and Coating to Improve Properties of Various Materials)
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Open AccessArticle
Exploring Bismuth Oxide Supported Kaolinite for Photocatalytic Application
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Punyanuch Thammaacheep, Pornpraphatson Phetthai, Suthitra Suchai, Panatda Jannoey and Duangdao Channei
Surfaces 2024, 7(3), 698-713; https://doi.org/10.3390/surfaces7030045 - 3 Sep 2024
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Bismuth oxide (Bi2O3) and Bi2O3–supported Kaolin were synthesized using household microwave–assisted methods (350 W, 5 min), with catalyst characteristics analyzed. XRD patterns confirmed the monoclinic structure of Bi2O3. Incorporating 20%w
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Bismuth oxide (Bi2O3) and Bi2O3–supported Kaolin were synthesized using household microwave–assisted methods (350 W, 5 min), with catalyst characteristics analyzed. XRD patterns confirmed the monoclinic structure of Bi2O3. Incorporating 20%w/w Kaolin increased the specific surface area of Bi2O3 from 6.2879 to 16.1345 m2/g, observed in FESEM images showing a hierarchical flower-like morphology resembling French fries alongside Kaolin plates. XRF analysis identified elements in Kaolin contributing to self–doping in band structure of Bi2O3, reducing its band gap and PL intensity. Kaolin/Bi2O3 composites demonstrated enhanced photocatalytic degradation of tetracycline (TC) under visible light, attributed to Bi2O3-generated radicals and increased surface area. The composite photocatalyst can be recycled up to three times. This research not only enhances the photocatalytic activity of Bi2O3 but also increases the value of a local waste material, Kaolin clay. Such enhancements could potentially extend to other metal oxides and abundant waste materials within the country.
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(This article belongs to the Special Issue Porous Materials for Photocatalysis)
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Open AccessReview
State of the Art Synthesis of Ag-ZnO-Based Nanomaterials by Atmospheric Pressure Microplasma Techniques
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Ayesha Khalid, Muhammad Naeem, Omar Atrooz, M. R. Mozafari, Fatemeh Anari, Elham Taghavi, Umair Rashid and Bushra Aziz
Surfaces 2024, 7(3), 680-697; https://doi.org/10.3390/surfaces7030044 - 2 Sep 2024
Cited by 1
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Atmospheric pressure microplasma is a simple, cost-effective, efficient, and eco-friendly procedure, which is superior to the traditional nanomaterials synthesis techniques. It generates high yields and allows for a controlled growth rate and morphology of nanomaterials. The silver (Ag) nanomaterials, with their unique physical
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Atmospheric pressure microplasma is a simple, cost-effective, efficient, and eco-friendly procedure, which is superior to the traditional nanomaterials synthesis techniques. It generates high yields and allows for a controlled growth rate and morphology of nanomaterials. The silver (Ag) nanomaterials, with their unique physical and chemical properties, exhibit outstanding antibacterial and antifungal properties. Similarly, zinc oxide (ZnO) nanomaterials, known for their low toxicity and relatively lower cost, find wide applications in wound repair, bone healing, and antibacterial and anticancer applications. The use of core–shell nanomaterials in certain situations where some nanoparticles can cause serious harm to host tissues or organs is a testament to their potential. A benign material is coated over the core to reduce toxicity in these cases. This review compares the numerous configurations of microplasma systems used for synthesizing nanomaterials and their use in producing Ag, ZnO, and their core–shell (Ag-ZnO) nanomaterials for biomedical applications. The summary also includes the effect of control parameters, including cathode diameter, gas flow rate, precursor concentration, voltage, and current, on the nanomaterial’s characteristics and applications. In addition, it provides a research gap in the synthesis of Ag, ZnO, and core–shell nanomaterials by this technique, as well as the development and limitations of this technique and the use of these nanoparticles for biomedical applications.
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Open AccessArticle
Surface Migration of Fatty Acid to Improve Sliding Properties of Hypromellose-Based Coatings
by
Maurice Brogly, Sophie Bistac and Armand Fahs
Surfaces 2024, 7(3), 666-679; https://doi.org/10.3390/surfaces7030043 - 2 Sep 2024
Abstract
Hypromellose (HM) is a cellulose-derived polymer of pharmaceutical grade that forms easily from thin films and coatings. As few studies concern HM-formulated systems, this study focuses on the formulation of HM films by incorporating a fatty acid additive, making it possible to control
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Hypromellose (HM) is a cellulose-derived polymer of pharmaceutical grade that forms easily from thin films and coatings. As few studies concern HM-formulated systems, this study focuses on the formulation of HM films by incorporating a fatty acid additive, making it possible to control surface properties such as wetting and slip behavior for pharmaceutical or medical applications. The results show that the addition of a very small amount (from 0.1 to 1% w/w) of fatty acid additive reduces HM film affinity for water and water vapor transmission rate, while film appearance and gloss are rather preserved. Surface properties were probed using wettability measurements, Tapping Mode AFM, ATR-FTIR spectrometry, and friction measurements. Tapping Mode AFM images show that the surface roughness reduces by up to 65%. Wettability results show that the surface energy decreases from 43 to 31 mJ.m−2, whereas surface FTIR spectrometry measurements demonstrate that fatty acid molecules migrate on the surface of the formulated films, the driving force being the microphase separation between the polar HM macromolecules and the hydrophobic additive, leading to the formation of a weak boundary layer with poor cohesion. As a consequence, the surface coefficient of friction significantly reduces from 0.38 to 0.08, and fatty acid molecules thus act as a lubricant, improving the sliding properties of HM-based coatings.
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(This article belongs to the Special Issue Surface Modification and Coating to Improve Properties of Various Materials)
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Open AccessArticle
Is the Interfacial Electrochemical Behavior of Quercetin the Same as That of Catechol Plus Resorcinol?
by
Vincent Ball
Surfaces 2024, 7(3), 653-665; https://doi.org/10.3390/surfaces7030042 - 25 Aug 2024
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Background: Electrodeposition of functional films from polyphenol-containing solutions has emerged as a new field of surface functionalization from bio-sourced molecules. There is, however, almost no knowledge about the chemical structure of such complex films. It is the aim of this research to use
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Background: Electrodeposition of functional films from polyphenol-containing solutions has emerged as a new field of surface functionalization from bio-sourced molecules. There is, however, almost no knowledge about the chemical structure of such complex films. It is the aim of this research to use the known electrodeposition of films made from catechol and resorcinol, two isomers of dihydroxybenzene, to understand the electrodeposition of a more complex polyphenol, quercetin, which is constituted from a fused catechol and resorcinol moiety. The aim of this article is hence to introduce some methodology in the interpretation of the electrochemical behavior of complex polyphenols starting from their building blocks. Methods: Cyclic voltammetry (CV) is used to deposit films from quercetin and from equimolar blends of catechol and resorcinol on amorphous carbon and gold working electrodes. The main experimental parameter was the potential sweep rate used during the CVs. Results: The CV of quercetin is not the exact sum of the CV of the catechol + resorcinol blends, but the major features are conserved, namely the presence of two main oxidation peaks affiliated to those of catechol and resorcinol but shifted to less anodic potentials. In addition, the anodic electron transfer coefficients of the two oxidation waves of quercetin are higher than those measured in the catechol resorcinol blend. However, film deposition ability is reduced with quercetin compared to catechol + resorcinol blend in probable relationship to steric hindrance occurring during the non-electrochemical crosslinking of the deposit. The quercetin-based films deposited at 10 mV·s−1 on gold electrodes are conformal and display some antioxidant activity.
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Open AccessArticle
Fish-Mimicking Hydrophilic and Hygroscopic Transparent Films with Long-Lasting Anti-Oil Adhesion and Its Application to PET Bottles
by
Jerred Wassgren, Hiroshi Kakiuchida, Tomoya Sato and Atsushi Hozumi
Surfaces 2024, 7(3), 643-652; https://doi.org/10.3390/surfaces7030041 - 20 Aug 2024
Abstract
With the recent ban on the production and use of long-chain perfluorinated compounds, the development of alternative approaches to prepare liquid-repellent surfaces that avoids the use of such compounds has become an urgent issue. We have succeeded in the development of fish-mimicking hydrophilic
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With the recent ban on the production and use of long-chain perfluorinated compounds, the development of alternative approaches to prepare liquid-repellent surfaces that avoids the use of such compounds has become an urgent issue. We have succeeded in the development of fish-mimicking hydrophilic transparent hydrogel-based films with long-lasting anti-oil adhesion properties. Such films could be prepared by simply mixing poly(vinylpyrrolidone) (PVP), nanoclay particles (NCPs), and a waterborne aminosilane (AOS) using an integral blend (IB) method. When submerged in water, these films displayed underwater superoleophobicity (advancing and receding contact angles (CAs) of diiodomethane were ~171°/~163°) with low CA hysteresis (less than 8°), because the hydrophilic nature of the films promoted the formation of a thin layer of adsorbed water on the topmost film surfaces, similar to fish scales. Furthermore, when our films were coated onto the inside of poly(ethylene terephthalate) (PET) bottles and pre-wetted using 80 °C hot water vapors, these film surfaces could effectively repel various oils and were able to maintain their oil-repellent properties for more than 5 weeks. These water-driven, non-perfluorinated transparent hydrogel-based films are expected to increase recycling of PET bottles for oils that are generally incinerated or landfilled.
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(This article belongs to the Special Issue Surface Modification and Coating to Improve Properties of Various Materials)
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Open AccessFeature PaperReview
Analysis, Assessment, and Mitigation of Stress Corrosion Cracking in Austenitic Stainless Steels in the Oil and Gas Sector: A Review
by
Mohammadtaghi Vakili, Petr Koutník, Jan Kohout and Zahra Gholami
Surfaces 2024, 7(3), 589-642; https://doi.org/10.3390/surfaces7030040 - 16 Aug 2024
Abstract
This comprehensive review examines the phenomena of stress corrosion cracking (SCC) and chloride-induced stress corrosion cracking (Cl-SCC) in materials commonly used in the oil and gas industry, with a focus on austenitic stainless steels. The study reveals that SCC initiation can occur at
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This comprehensive review examines the phenomena of stress corrosion cracking (SCC) and chloride-induced stress corrosion cracking (Cl-SCC) in materials commonly used in the oil and gas industry, with a focus on austenitic stainless steels. The study reveals that SCC initiation can occur at temperatures as low as 20 °C, while Cl-SCC propagation rates significantly increase above 60 °C, reaching up to 0.1 mm/day in environments with high chloride concentrations. Experimental methods such as Slow Strain Rate Tests (SSRTs), Small Punch Tests (SPTs), and Constant-Load Tests (CLTs) were employed to quantify the impacts of temperature, chloride concentration, and pH on SCC susceptibility. The results highlight the critical role of these factors in determining the susceptibility of materials to SCC. The review emphasizes the importance of implementing various mitigation strategies to prevent SCC, including the use of corrosion-resistant alloys, protective coatings, cathodic protection, and corrosion inhibitors. Additionally, regular monitoring using advanced sensor technologies capable of detecting early signs of SCC is crucial for preventing the onset of SCC. The study concludes with practical recommendations for enhancing infrastructure resilience through meticulous material selection, comprehensive environmental monitoring, and proactive maintenance strategies, aimed at safeguarding operational integrity and ensuring environmental compliance. The review underscores the significance of considering the interplay between mechanical stresses and corrosive environments in the selection and application of materials in the oil and gas industry. Low pH levels and high temperatures facilitate the rapid progression of SCC, with experimental results indicating that stainless steel forms passive films with more defects under these conditions, reducing corrosion resistance. This interplay highlights the need for a comprehensive understanding of the complex interactions between materials, environments, and mechanical stresses to ensure the long-term integrity of critical infrastructure.
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(This article belongs to the Special Issue Surface Modification and Coating to Improve Properties of Various Materials)
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Open AccessArticle
Study on the Lubrication Performance of Graphene-Based Polyphosphate Lubricants in High-Temperature Steel–Steel Friction Pair
by
Kaifu Mi, Qingqing Ding, Xiangru Xu, Yu Lei, Juncheng Wang and Ning Kong
Surfaces 2024, 7(3), 571-588; https://doi.org/10.3390/surfaces7030039 - 11 Aug 2024
Abstract
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In the study, a hybrid lubricant was prepared by introducing graphene into a polyphosphate lubricant. In the tribological test of a steel/steel friction pair at the high temperature of 800 °C, the addition of a small proportion of graphene significantly enhances the lubrication
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In the study, a hybrid lubricant was prepared by introducing graphene into a polyphosphate lubricant. In the tribological test of a steel/steel friction pair at the high temperature of 800 °C, the addition of a small proportion of graphene significantly enhances the lubrication performance of polyphosphate at elevated temperatures. The coefficient of friction and the wear were obviously held down while the surface quality of the high-temperature friction pair was enhanced effectively with the graphene-strengthened polyphosphate lubricant, compared with the dry sliding condition. Through scanning electron microscopy and Raman spectroscopy analysis, the formation mechanism of tribofilm and the antiwear performance of the hybrid lubricant are further explained. This lubricant effectively combines the advantages of both; the combination of polyphosphate melted at elevated temperature with graphene and metal surfaces ensures the self-sealing of the friction contact area and brings better high-temperature oxidation resistance. At the same time, the presence of graphene provides excellent strength to the friction film and ensures the anti-wear and wear-resistant performance of the lubricant at high temperatures.
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Open AccessArticle
Evaluation of Photocatalytic Hydrogen Evolution in Zr-Doped TiO2 Thin Films
by
Luis F. Garay-Rodríguez, M. R. Alfaro Cruz, Julio González-Ibarra, Leticia M. Torres-Martínez and Jin Hyeok Kim
Surfaces 2024, 7(3), 560-570; https://doi.org/10.3390/surfaces7030038 - 9 Aug 2024
Abstract
Doping titanium dioxide has become a strategy for enhancing its properties and reducing its recombination issues, with the aim of increasing its efficiency in photocatalytic processes. In this context, this work studied its deposition over glass substrates using a sol–gel dip coating methodology.
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Doping titanium dioxide has become a strategy for enhancing its properties and reducing its recombination issues, with the aim of increasing its efficiency in photocatalytic processes. In this context, this work studied its deposition over glass substrates using a sol–gel dip coating methodology. The effect of doping TiO2 with Zirconium cations in low molar concentrations (0.01, 0.05, 0.1%) in terms of its structural and optical properties was evaluated. The structural characterization confirmed the formation of amorphous thin films with Zr introduced into the TiO2 cell (confirmed by XPS characterization), in addition to increasing and defining the formed particles and their size slightly. These changes resulted in a decrease in the transmittance percentage and their energy band gap. Otherwise, their photocatalytic properties were evaluated in hydrogen production using ethanol as a sacrificial agent and UV irradiation. The hydrogen evolution increased as a function of the Zr doping, the sample with the largest Zr concentration (0.1% mol) being the most efficient, evolving 38.6 mmolcm−2 of this gas. Zr doping favored the formation of defects in TiO2, being responsible for this enhancement in photoactivity.
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(This article belongs to the Special Issue Recent Advances in Catalytic Surfaces and Interfaces)
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