Metal Surface Research Articles

Modulating the electronic structure of Ni and Co in core-shell structured catalysts to enhance the efficiency of reductive amination of pyruvic acid

A core-shell structured catalyst 3Ni-7Co@SiO2-0.2 was created to facilitate the reductive amination of pyruvic acid into alanine and the yield of alanine is up to 99 %. The SiO2 shell played a crucial role in spatial isolation effect, preventing the direct hydrogenation of pyruvic acid and improving the selectivity of alanine. By inter-doping Ni and Co, the electronic structure and properties are adjusted, the d-band center is reduced which is beneficial to the desorption of the product and the reaction barrier is reduced. Furthermore, it is proposed that catalysts exhibit better reductive amination reaction performance when there is a smaller difference in adsorption energy between NH3 and H2 atoms on the metal surface.

Understanding the Impact of Hydroxyls on Synthesizing the Bimetallic Alloy Pt3Co on Al2O3 for CO-PROX

The anchoring effect between surface hydroxyls (–OH) and metal species has been extensively utilized to enhance catalyst stability. Nevertheless, few studies have investigated the impact of alloying process involving different types of –OH species. In this research, we discovered that the formation of the alloy particles Pt3Co was significantly influenced by the presence of distinct –OH species on Al2O3. Intriguingly, those Pt3Co alloy particles exclusively formed on α-Al2O3 owing to the weak interaction between both Pt and Co species and the triply bridging hydroxyls (µ3-OH). In contrast, Pt and Co species were found to be separately dispersed on γ-Al2O3 because of the strong anchoring effect of terminal hydroxyls (µ1-OH), especially for Co atoms. Density functional theory (DFT) calculations highlighted the difference in adsorption energies of the two metals on different hydroxyl groups, providing a theoretical rationale for the influence of hydroxyl groups on alloy formation. The presence of Pt3Co alloy resulted in a fourfold increase in the specific catalytic rate of Pt3Co/α-Al2O3 in CO-PROX compared to Pt3Co/γ-Al2O3. Arguably for the first time, this study demonstrates the association between alloy formation and –OH groups, providing a unique perspective on the design of alloy catalysts.

Ageing of commercial austenitic, martensitic and duplex stainless steel surfaces after formation of laser-induced periodic surface structures by fs-laser irradiation

The time-dependent wetting behavior was investigated for commercially available austenitic, martensitic and duplex stainless steel surfaces after femtosecond (fs) laser irradiation. For this purpose, highly regular LIPSS with almost identical geometric properties were generated on the stainless steels in an air environment by near-infrared fs-laser processing (λ = 1025 nm, τ = 300 fs, frep = 100 kHz, v = 0.67 m/s, Δx = 6 μm, F = 1.1 J/cm2) and compared to the polished initial surfaces as reference. The wetting with distilled water was evaluated as a function of aging time by contact angle measurements using the sessile drop method. The laser-induced morphological, topographical and chemical alteration of the surface was characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, glow-discharge optical emission spectroscopy as well as high-resolution imaging and scanning transmission electron microscopy. Despite an almost identical LIPSS-based topography alteration, the stainless steels revealed very different ageing behavior. For permanently used samples, it was shown that the ageing effect is less pronounced than for samples that were stored in ambient air following fs-laser irradiation until the wetting measurement. The results obtained make an important contribution to understanding and controlling the ageing effect of metal surfaces and thus facilitate the transfer of LIPSS-based functional surface engineering and design to industrial processes.

Eco-friendly modified chitosan as corrosion inhibitor for carbon steel in acidic medium: Experimental and in-depth theoretical approaches

The industrial and medical sectors have a great interest in chitosan due to its unique properties, such as abundance, renewability, non-toxicity, antibacterial activity, biodegradability, and polyfunctionality. In this work, two modified chitosan Schiff bases (ChSB-1 and ChSB-2) were made using condensation methods, and their potential as corrosion inhibitor for carbon steel in 1 M HCl was investigated using chemical and electrochemical techniques. The ChSB-1 and ChSB-2 inhibitors exhibited remarkable inhibitory performance, as evidenced by the mass loss data, which showed 89.3 % and 91.5 % efficacy at 1 mM concentration, respectively. Because of the electron-donor substituent of methoxy (–OCH3), ChSB-2's active sites have more delocalized electrons than ChSB-1's. The PDP results showed that both ChSB-1 and ChSB-2 inhibitors have anti-corrosion characteristics because heteroatoms caused a protective layer to develop that functioned as mixed-typed inhibitors. The calculated adsorption-free energy ∆Gadso for ChSB-1 and ChSB-2, respectively, was found −36.1 and − 37.1 kJ mol−1. The ChSB-1 and ChSB-2 inhibitors adsorb on carbon steel in acidic conditions through physisorption and chemisorption interactions, and their adsorption is in line with the Langmuir adsorption model. Inhibited and uninhibited metallic surfaces were subjected to surface morphological assessments using contact angle (CA), the scanning electron microscopy and the energy dispersive X-ray (SEM/EDX) analysis. The DMol3 part of Materials Studio 7.0 software was used to perform the quantum chemical calculations based on DFT to visualize the structural features. Studies from quantum chemistry suggest the possibility of surface interaction between the unoccupied orbitals of the metal surface and the inhibitors ChSB-1, ChSB-2, ChSB-1H+, and ChSB-2H+. The results clearly show that the two inhibitors work well as environmentally friendly carbon steel corrosion inhibitors in acidic medium. This could be advantageous for industrial procedures such as pickling, cleaning, acidizing oil drilling in oil wells, and using citrus to de-sediment boilers.

Microstructure and mechanical properties of wire and arc additive manufactured 2319 aluminum alloy treated by laser shock peening

The components manufactured by Wire and Arc Additive Manufacturing (WAAM) have some problems to be solved urgently, such as uneven microstructure, numerous pore defects, and residual tensile stress. Laser Shock Peening (LSP) is an innovative and advanced surface modification technology that improves mechanical characteristics by inducing significant plastic deformation and high compressive residual stress on metal surfaces. Therefore, combining LSP with WAAM is expected to solve its existing problems. In this work, LSP with different energy parameters was used to post-process the WAAM 2319 aluminum alloy. The results indicated that LSP could improve the microstructure, eliminate near-surface pores, harden the surface layer, and induce a residual compressive stress layer, and the effect was more effective with the increase of laser energy applied. The yield strength of the peened specimens significantly increased by 60.73 %, and the ultimate tensile strength also increased by 16.03 %. The hole fatigue life of the peened specimens was significantly improved, increasing by 179.8 % and 261.7 %, respectively, applying laser energies of 5 J and 10 J. Therefore, the engineering industry may benefit from a combination of LSP and WAAM technology.

Mechanism of the hydrazine hydrate electrooxidation reaction on metallic Ni electrodes in alkaline media as revealed by electrochemical methods, online DEMS and ex situ XPS

Metallic Ni surface was examined as a catalyst for the hydrazine hydrate oxidation reaction (HHOR) by cyclic voltammetry, chronoamperometry, and online differential electrochemical mass-spectrometry (DEMS). It was found that N2 is the sole gaseous product formed during the HHOR on Ni and 4 electrons are transferred in the process, which corresponds to a complete oxidation of the hydrazine molecule. The mechanism of the HHOR on the Ni surface involves OH− and adsorbed OHads intermediate, the latter improving the rate of the HHOR. Ni catalysts were found to be poisoned during the HHOR, the extent of poisoning depending on the number of surface sites, hydrazine concentration, and the α-Ni(OH)2 coverage. Ex situ X-ray photoelectron spectroscopy (XPS) measurements were performed to characterize the species poisoning Ni surface.

Hybrid Quantum Mechanical, Molecular Mechanical, and Machine Learning Potential for Computing Aqueous-Phase Adsorption Free Energies on Metal Surfaces.

Performing reliable computer simulations of elementary processes occurring at metal-water interfaces is pivotal for novel catalyst design in sustainable energy applications. Computational catalyst design hinges on the ability to reliably and efficiently compute the potential energy surface (PES) of the system. Due to the large system sizes needed for studying processes at liquid water-metal interfaces, these systems can currently not be described using density functional theory (DFT). In this work, we used a hybrid quantum mechanical, molecular mechanical, and machine learning potential for studying the adsorption behavior of phenol, atomic hydrogen, 2-butanol, and 2-butanone on the (0001) facet of Ru under reducing conditions when Ru is not oxidized. Specifically, we describe the adsorbate and the surrounding metal atoms at the DFT level of theory. Here, we also considered the electrostatic field effect of the water molecules on adsorbate-metal interactions. Next, for the water-water and water-adsorbate interactions, we used established classical force fields. Finally, for the water-Ru surface interaction, for which no reliable force fields have been published, we used Behler-Parrinello high-dimensional neural network potentials (HDNNPs). Employing this setup, we used our explicit solvation for metal surface (eSMS) approach to compute the aqueous-phase effect on the low-coverage adsorption of selected molecules and atoms on the (0001) facet of Ru. In agreement with previous experimental and computational studies of oxygenated molecules over transition metal facets, we found that liquid water destabilizes the tested adsorbates on Ru(0001). Interestingly, our findings indicate that adsorbates on Ru are less affected by the presence of an aqueous phase than on other transition metals (e.g., Pt), highlighting the necessity of experimental investigations of Ru-based catalytic systems in liquid water.

Hydrogen adsorption on fcc metal surfaces towards the rational design of electrode materials

The successful large-scale implementation of hydrogen as an energy vector requires high performance electrodes and catalysts made of abundant materials. Rational materials design strategies are the most efficient means of reaching this goal. Here we present a study on the adsorption of H-atoms onto fcc transition metal surfaces and propose descriptors for the rational design of electrodes and catalysts by means of correlations between fundamental properties of the materials and among other properties, their experimentally measured performance as hydrogen evolution electrodes (HEE). A large set of quantum mechanical modelling data at the DFT level was produced, covering the adsorption of H-atoms onto the most stable surfaces (100), (110) and (111) of: Ag, Au, Co, Cu, Ir, Ni, Pd, Pt and Rh. For each material and surface, a coverage dependent set of minimum energy structures was produced and chemical potentials for adsorption of H-atoms were obtained. Averaging procedures are here proposed to approach modelling to the experiments. Several correlations between the computed data and experimentally measured quantities are done to validate our methodology: surface plane dependent adsorption energies, chemical potentials and experimentally determined surface energies and work functions. We search for descriptors of catalytic activity by testing correlations between the DFT data obtained from our averaging procedures and experimental data on HEE performance. Our methodology allows us to obtain linear correlations between the adsorption energy of H-atoms and the exchange current density (i0) in a HEE, avoiding the volcano-like plots. We show that the chemical potential has limitations as a descriptor of i0 because it reaches an early plateau in terms of i0. Simple quantities obtained from database data such as the first stage electronegativity (χ) as devised by Mulliken has a strong linear correlation i0. With a quantity we denominate modified second-stage electronegativity (χ2m) we can reproduce the typical volcano plot in a correlation with i0. A theoretical and conceptual framework is presented. It shows that both χ and χ2m, that depend on the first ionization potential, second ionization potential and electron affinity of the elements can be used as descriptors in rational design of electrodes or of catalysts for hydrogen systems.

Friction Mechanism of Sulfur-Containing Lubricant Additives Confined between Fe(100) Substrates.

Sulfur-containing lubricant additives can chemically react with metal surfaces under extreme conditions, such as high temperature and high pressure, forming protective films on the surfaces. However, the formation mechanisms and the friction-reducing and antiwear properties of these films remain unclear. In this study, we investigated the friction process of sulfur-containing additives confined between two iron surfaces using reactive molecular dynamics simulations. Our research revealed that in systems with a higher S/C ratio, an iron sulfide layer formed on the iron surfaces with Fe-S-Fe bridging bonds at the interface, resulting in relatively smaller friction and wear even under higher loads. However, in systems with lower S/C ratios, the presence of numerous interfacial Fe-Cn-Fe bridging bonds, caused by the hydrocarbon radicals released from the additives, led to the formation of thick amorphous shearing bands at the interface between the two substrates. In this case, the distributed sulfur atoms also exhibited some effect in reducing the shear resistance of the amorphous shearing bands due to the weak strength of S-Fe bonds compared to the strength of C-Fe bonds. These atomic-level insights help understand the antiwear characteristics of sulfur-containing lubricant additives confined between iron substrates.

Assessment of Warionia saharea Essential Oil as a Green Corrosion Inhibitor for Mild Steel in HCl: Experimental and Computational Studies

The objective of this research work is the study of the inhibitory effect of Warionia saharea essential oil (WSEO) on the corrosion of mild steel (MS) in molar HCl solution, employing both experimental and theoretical methods. This inhibitory effect (IE) has been evaluated by using a combination of weight loss measurements (LW) and various electrochemical methods, such as open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) experiments. The LW results indicated that IE increased with inhibitor concentration, reaching 83.34% at 3.00 g/L. The PDP analysis suggested that WSEO functions as a mixed inhibitor, while in the EIS results the Rct values increased with inhibitor concentration to reach 165.8 Ω cm2 at 2.00 g/L, suggesting a defensive film formation by WSEO molecules over the metallic surface. The thermodynamic study demonstrated that the WSEO molecules adsorption on the MS surface followed a Langmuir isotherm, involving mixed physical and chemical (physicochemical) adsorption on the MS surface. Theoretical methods, including density functional theory (DFT) and molecular dynamics (MD) simulations, were employed to elucidate the inhibition mechanisms of the three main components of WSEO. The quantum chemical analysis, using density functional theory (DFT) and molecular dynamics (MD) simulations, showed a low ΔEgap value of 6.30 eV and a low adsorption energy (Eads) value on an Fe (110) substrate of −258 Kcal/mol for (E)-Nerolidol, indicating the significant contribution of this molecule to the overall corrosion inhibition effect of WSEO. The scanning electron microscope (SEM) analysis verified the presence of a protective film formed by the inhibitor on the MS surface. This study highlights the potential of WSEO as a sustainable and green corrosion inhibitor in acidic environments.

Flexible fabrication of core/shell nanoparticles for tailored infrared emissivity on aluminum via femtosecond laser self-deposition.

A metal surface with controllable infrared emissivity has a wide range of applications. However, a flexible and simple fabrication method is needed. Here, a controllable femtosecond laser self-deposition technology was developed to fabricate Al@AlOx core/shell micropillars (MPs) with diverse size distribution on the aluminum surface in a single-step operation under ambient conditions. By establishing a deterministic relationship between pulse-repetition frequency (PRF) and particle size distribution (PSD), we achieved continuous control of the infrared emissivity of the surface by lower PRF, ranging from low (0.31) to high (0.93). Additionally, by using higher PRF, we attained dual-band emissivity control, featuring high emissivity in the range of 10-14 µm and near-continuous change in the range of 2.5-10 µm.

Growth Mediated Disassembly of Cucurbit[8]uril Cross‐linked Static Cubic Self‐assembly of Silver Nanoparticles

AbstractStatic self‐assembly resides in thermodynamically stable global minima of the energy landscape, whereas dynamic self‐assembly occupies local minima of the energy profile and remains in the ordered state for a limited time via dissipation of energy to surroundings. This makes the spatiotemporal control over the assembly and disassembly mechanism easily controllable in the case of dynamic self‐assembly. However, due to the higher thermal stability of static self‐assembly, it is very challenging to perform reverse engineering on these types of systems. Herein we report growth reaction‐based reversal of static silver cubes obtained via cucurbit[8]uril (CB[8]) crosslinked self‐assembly of silver nanoparticles (AgNP). The AgNP building units with variable CB[8] surface coverage have been used as seeds onto which deposition of gold via growth reaction has been performed. The disassembly of supracube structure has been controlled by the formation of [AuCl4]−–CB[8] complex and successive reduction of [AuCl4]− to Au0 on the surface of the seed. The resulting monodispersed isotropic nanoparticles, formed from the CB[8] based cubic self‐assembly after growth, exhibit Au−Ag bimetallic nature. Quenching of the fluorogenic response from the hydrophobic dye coumarin‐7, added after growth, suggests direct interaction with the metallic nanoparticle surface after disassembly and thereby confirms successful growth reaction mediated reversal of self‐assembly.

A facile preparation of durable superhydrophobic PFA coatings with superior anti-icing, anti-corrosion and self-cleaning performance

The potential of superhydrophobic coatings for various applications has been widely recognized. However, preparing durable superhydrophobic coatings on metal surfaces remains a significant challenge. Perfluoroalkoxy Alkane (PFA), a fluorine-rich material, has recently emerged as a promising candidate for constructing superhydrophobic coatings. In this study, a mechanically stable superhydrophobic PFA coating was prepared using a simple combination of electrodeposition and annealing. The prepared PFA coating displays excellent water repellency, as evidenced by a water contact angle of 171 ± 0.3° and a sliding angle of 1.0 ± 0.4° The water contact angle of the coating only decreases by 0.6°after undergoing 400 tape stripping tests, indicating the remarkable stability. The PFA coating significantly prolongs the freezing time of water droplets on a cool surface at temperatures of -6 °C, -8 °C, and -10 °C, with improvements of 19.4, 72.5, and 47.8 times respectively. The corrosion current density on the coated surface is reduced by four orders of magnitude compared to bare aluminum alloy, and the PFA coating exhibits a high inhibition corrosion efficiency of 99.995 %. Furthermore, the coating possesses exceptional self-cleaning performance by repelling dirt particles and maintaining a clean surface. Consequently, the developed superhydrophobic PFA coating holds significant promise for long-lasting anti-icing, anti-corrosion and self-cleaning applications.

Effect of ion-specific water structures at metal surfaces on hydrogen production

Water structures at electrolyte/electrode interfaces play a crucial role in determining the selectivity and kinetics of electrochemical reactions. Despite extensive experimental and theoretical efforts, atomic-level details of ion-specific water structures on metal surfaces remain unclear. Here we show, using scanning tunneling microscopy and noncontact atomic force microscopy, that we can visualize water layers containing alkali metal cations on a charged Au(111) surface with atomic resolution. Our results reveal that Li+ cations are elevated from the surface, facilitating the formation of an ice-like water layer between the Li+ cations and the surface. In contrast, K+ and Cs+ cations are in direct contact with the surface. We observe that the water network structure transitions from a hexagonal arrangement with Li+ to a distorted hydrogen-bonding configuration with Cs+. These observations are consistent with surface-enhanced infrared absorption spectroscopy data and suggest that alkali metal cations significantly impact hydrogen evolution reaction kinetics and efficiency. Our findings provide insights into ion-specific water structures on metal surfaces and underscore the critical role of spectator ions in electrochemical processes.

High performance ultra-thin lithium metal anode enabled by vacuum thermal evaporation

The passivation layer that naturally forms on the lithium metal surface contributes to dendrite formation in lithium metal batteries by affecting lithium nucleation uniformity during charging. Herein, we propose using vacuum thermal evaporation to produce a high-performance ultra-thin lithium metal anode (≤25 µm) with a native layer much thinner than that of extruded lithium. The evaporated lithium metal shows significantly reduced charge-transfer resistance, resulting in uniform and dense lithium plating in both carbonate and ether electrolytes. This study reveals that the evaporated lithium metal outperforms the extruded version in ether electrolyte and with LiFePO4 cathodes, showing a 30% increase in cycle life. Additionally, when paired with LiNi0.6Mn0.2Co0.2O2 cathodes in carbonate electrolyte, the evaporated anode’s cycle life is tripled compared to the extruded lithium metal. This demonstrates that vacuum thermal evaporation is a viable method for producing ultra-thin lithium metal anodes that prevent dendrite growth due to their excellent surface condition.

CAVITATION EROSION IN FRANCIS TURBINES

The phenomenon of secondary flow is a global problem that causes cavitation erosion in hydraulic equipment. Cavitation is a phenomenon of localised corrosion of the metal surface leading to instability and highly uneven flow behaviour with a consequent excessive noise, vibration, and decreased efficiency in Francis, Kaplan, and other turbines. Both Kaplan and Francis turbines are reaction turbines. Francis turbines (FT) are used worldwide due to their relatively compact design, high efficiency, and operation underwater at heights ranging from 100 to 300 m with an efficiency ranging from 90% to 95%. The article analyses the latest relevant research conducted by various researchers on different turbine components. The analysis shows that this type of erosion depends on flow characteristics, surface, and properties of the material eroding. Tools for design optimisation, cavitation erosion, and well-conducted experiments will provide results for identifying and reducing erosion. Although some researchers conducted experimental work to study the effect of cavitation erosion, literature on computational fluid dynamics (CFD) is very scarce. Over the past two decades, experts have been applying CFD methods to detect cavitation by examining areas where the pressure is below the vapour pressure with a single-phase model. Most studies do not consider the impact of cavitation bubbles on the flow field. However, these methods cannot provide detailed information, such as the impact of cavitation on efficiency or a more accurate prediction of the cavitation bubble size. Some researchers use cavitation inducers and some of the latest visualisation methods as experimental tools to study cavitation phenomena. In the last decade, a numerical methodology has been widely used in research and experiments, yielding significant results. Studying cavitation erosion in hydroelectric turbine systems presents a complex challenge for future research. Many parameters and features still require further investigation. All the discussed studies have established that cavitation phenomena require state-of-the-art equipment for their detection and visualisation. Moreover, more work is necessary for the numerical assessment of cavitation. Keywords: hydroelectric turbine, cavitation erosion, computational fluid dynamics.

SEDIMENTATION IN HYDROELECTRIC POWER TURBINES

The primary cause of erosive wear and energy loss is friction, and reportedly, one-third of the world’s energy resources go to overcome friction by several methods. The presence of deposits in water is a common problem in mountainous regions and some Ukrainian hydroelectric power stations. Hydro turbines face serious issues related to erosion from deposits during operation. Erosive wear occurs due to the impact of solid particles against a solid surface. The current environment contains particles whose velocity is sufficient to damage metal surfaces. Various researchers have conducted numerous studies to minimise the effect of deposit erosion in multiple locations of Francis turbine components (FT). For this purpose, they performed field investigations, experimental measurements, empirical modelling, computational fluid dynamics (CFD) work, and other methods. Various empirical models have been used to describe erosive wear in terms of material and fluid properties. They established that, for ductile materials, maximum erosion occurs at an impact angle of 30°, whereas for brittle materials, it occurs in the range of 80–90°. In the literature, various experimental methods are available to quantitatively assess slurry erosion, such as the rotating disk apparatus (RDA), slurry tank testing, jet erosion testing, and rotating drum testing. Due to manufacturing technologies used in mechanical processing processes, the exposed surface has a certain absolute roughness that increases during machine operation due to abrasion or erosion. Therefore, surface texture leads to increased energy efficiency losses during operation. Technological advancements have facilitated the widespread use of computational tools to address deposit erosion issues. In recent decades, numerical methodology has been a widely used and effective tool, yielding tangible and reliable results. This study examines potential methods for detecting and reducing deposits. This type of erosion depends on flow characteristics, surface properties, and properties of the eroding material. The article provides comprehensive information on sedimentation (deposits) causing wear in hydraulic turbines. Keywords: hydroelectric turbine, sedimentation erosion, computational fluid dynamics, fluid-structure interaction.

Molecule-Supported Magnetic-Atom Dimers on Au(111): Multiple Structures and Kondo Resonances

Magnetic-atom dimers on surface provide a powerful platform to study single spin interactions and qubit controls. They have been experimented on bare and thin-insulator-covered metallic surfaces, with strong and weak couplings between atoms and surfaces, respectively. If they are embedded in single molecules on surfaces, they may allow new geometric and electronic configurations as well as different coupling levels. But such system has rarely been studied. Here we report our scanning tunneling microscopy studies for molecule-supported magnetic-atom dimers on Au(111). Through on-surface reactions, Fe-Co dimers were embedded to porphyrin molecules in three different types. We observed zero-bias resonance in our scanning tunneling spectroscopy from one type with the Kondo temperature lower than Co-porphyrin molecules. Based on our density functional theory calculation results, atomic structures of three dimer structures were reproduced, and the observed Kondo behaviors were explained. Our study shows that the molecule supported magnetic-atom dimers can be a useful platform for studying spin physics and quantum information science.

Development and performance evaluation of green superhydrophobic coating for fouling and corrosion protection

In this paper, a simple and environmentally friendly superhydrophobic stearic acid-modified zinc-nickel-cobalt composite coating (SA@ZNC) is presented. The zinc-nickel-cobalt (ZNC) coating with petal-like micro/nano-rough structure was constructed on the metal surface by combining electrodeposition and chemical substitution techniques. Subsequently, the coating was modified with low surface energy by adding stearic acid, and the SA@ZNC coating with excellent superhydrophobicity (water contact angle of 161.08 ± 0.31° and rolling angle of 3.50 ± 0.54°) was prepared. The coating is self-cleaning against a wide range of simulated contaminants and can remain superhydrophobic in air for over a year. Changes in pH do not significantly affect the superhydrophobicity and at low temperatures, the freezing time of water droplets on the coating was extended by 2.1 times compared to a blank steel sheet. Furthermore, the SA@ZNC coating demonstrated remarkable robustness, withstanding 30 minutes of water impact, a wear mass of 0.2 % after rubbing with weights over 2400 mm and retaining its superhydrophobicity after 80 tape stripping cycles. The results of the corrosion protection tests demonstrated that the SA@ZNC coating provided excellent corrosion protection for N80 steel, exhibiting a current density two orders of magnitude lower than that of the blank sample. Furthermore, the coating exhibited a corrosion inhibition rate of 95.75 ± 0.33 % and excellent charge transfer resistance. The multiple protection mechanisms and homogeneous micro/nanostructure of the coatings resulted in significantly better corrosion resistance than most of the reported zinc-nickel based coatings. The use of low-energy consumption methods and environmentally friendly modifiers positions this coating for large-scale production and potential applications in sectors like food and medicine, with promising implications for corrosion protection in various industries.

Improvement of tribological and anti-corrosive performance of MXene nanosheets by grafting polymer brush

Herein, the anti-corrosive polymer brush functionalized MXene (P-MBTS2MA@MXene) was successfully prepared via surface-initiated polymerization. First, the dopamine initiator (DA-Br) can self-assemble onto MXene nanosheets formation of initiator modified MXene (PDA-Br@MXene) via spontaneous oxidative polymerization, then the corrosion inhibitor MBT derivative MBTS2MA monomer was grafted onto MXene nanosheets through surface-initiated atom transfer radical polymerization (SI-ATRP) to obtain polymer brush P-MBTS2MA functionalized MXene (P-MBTS2MA@MXene). The prepared P-MBTS2MA@MXene served as lubricant additive, manifesting good tribological properties with a low COF of 0.098 % and 94.8 % wear-reduction, which is attributed to the shielding effect and protective film formed by P-MBTS2MA@MXene. Additionally, the grafting P-MBTS2MA endows MXene nanosheets with improved anti-corrosion property, which prevents further corrosion of the metal surface via releasing corrosion resistance molecule MBT.