Surface Modification Of Metals Research Articles

Organic-Inorganic Biocompatible Coatings for Temporary and Permanent Metal Implants.

The general trend of increasing life expectancy will consistently drive the demand for orthopedic prostheses. In addition to the elderly, the younger population is also in urgent need of orthopedic devices, as bone fractures are a relatively common injury type; it is important to treat the patient quickly, painlessly, and eliminate further health complications. In the field of traumatology and orthopedics, metals and their alloys are currently the most commonly used materials. In this context, numerous scientists are engaged in the search for new implant materials and coatings. Among the various coating techniques, plasma electrolytic oxidation (PEO) (or micro-arc oxidation-MAO) occupy a distinct position. This method offers a cost-effective and environmentally friendly approach to modification of metal surfaces. PEO can effectively form porous, corrosion-resistant, and bioactive coatings on light alloys. The porous oxide surface structure welcomes organic molecules that can significantly enhance the corrosion resistance of the implant and improve the biological response of the body. The review considers the most crucial aspects of new combined PEO-organic coatings on metal implants, in terms of their potential for implantation, corrosion resistance, and biological activity in vitro and in vivo.

Surface treatment of metal by combined particle beam

This work is related to modeling of metal surface modification process by combined particles beam. On the basis of thermodynamics of irreversible processes, including equations of state in differential form, a nonlinear model is formulated. The model takes into account the interaction of thermal, diffusion and mechanical waves and finiteness of relaxation times of thermal and diffusion processes. For the combined particle flow such model is proposed for the first time. The numerical algorithm is based on implicit difference schemes. The study of the interaction of waves of different nature is carried out on the example of a copper target treated with nickel and gold particles. It is shown that deformations take the maximal value at the left boundary, which is directly related to the presence of impurity concentration gradients. Depending on the pulse duration, the difference between the extrema on the elastic wave becomes less significant. With increasing temperature, obviously, the diffusion process accelerates. The propagation velocities of the interacting waves are different. The character of distributions of concentrations of introduced particles directly depends on the value of parameters proportional to relaxation times.

Iron Oxide Nanoparticles as Promising Antibacterial Agents of New Generation.

Antimicrobial resistance (AMR) is growing into a major public health crisis worldwide. The reducing alternatives to conventional agents starve for novel antimicrobial agents. Due to their unique magnetic properties and excellent biocompatibility, iron oxide nanoparticles (IONPs) are the most preferable nanomaterials in biomedicine, including antibacterial therapy, primarily through reactive oxygen species (ROS) production. IONP characteristics, including their size, shape, surface charge, and superparamagnetism, influence their biodistribution and antibacterial activity. External magnetic fields, foreign metal doping, and surface, size, and shape modification improve the antibacterial effect of IONPs. Despite a few disadvantages, IONPs are expected to be promising antibacterial agents of a new generation.

Helicenes on Surfaces: Stereospecific On-Surface Chemistry, Single Enantiomorphism, and Electron Spin Selectivity.

Helicenes represent an important class of chiral organic material with promising optoelectronic properties. Hence, functionalization of surfaces with helicenes is a key step towards new organic material devices. This review presents different aspects of adsorption and modification of metal surfaces with different helicene species. Topics addressed are chiral crystallization, that is, 2D conglomerate versus racemate crystallization, breaking of mirror-symmetry in racemates, chirality-induced spin selectivity, and stereoselective on-surface chemistry.

Electrical and Dielectric Properties of Polymer-Metal Hybrid Nanocomposites - A Short Review

Polymer-metal hybrid nanocomposites have garnered significant attention in recent years due to their exceptional electrical and dielectric properties, which find applications in a wide range of industries, including electronics, energy storage, and advanced materials. This review article provides a comprehensive overview of the current state-of-the-art in the field of polymer-metal hybrid nanocomposites, with a particular focus on their electrical and dielectric properties. The first section of the review delves into the synthesis and fabrication techniques employed to create these nanocomposites, highlighting the importance of controlling the dispersion and distribution of metal nanoparticles within the polymer matrix. Various approaches, such as in-situ polymerization, melt mixing, and electrospinning, are discussed in detail, along with their respective advantages and limitations.The subsequent sections explore the influence of metal nanoparticles on the electrical conductivity and dielectric constant of the nanocomposites. The role of factors such as nanoparticle size, shape, and concentration in determining these properties is thoroughly examined. Moreover, the impact of metal surface modifications and the choice of polymer matrix on enhancing electrical and dielectric performance are also addressed. In addition to discussing fundamental aspects, this review highlights practical applications of polymer-metal hybrid nanocomposites in the development of high-performance capacitors, sensors, electromagnetic shielding materials, and flexible electronics. The potential for these materials to revolutionize various technological sectors is discussed, emphasizing their role in advancing miniaturization, energy efficiency, and durability. Furthermore, the review outlines current challenges and future prospects in the field, including the need for a deeper understanding of the underlying mechanisms governing electrical and dielectric behavior in these nanocomposites. Emerging trends such as the incorporation of 2D materials and the development of multifunctional hybrid systems are also explored, hinting at exciting avenues for further research and innovation. In conclusion, polymer-metal hybrid nanocomposites offer a promising platform for tailoring electrical and dielectric properties to meet the demands of modern technology. This review serves as a valuable resource for researchers, engineers, and scientists seeking to explore the potential of these materials and drive advancements in the field of electrical and dielectric engineering.

Synergistic Bulk and Surface Engineering for Expeditious and Durable Reversible Protonic Ceramic Electrochemical Cells Air Electrode.

Reversible protonic ceramic electrochemical cells (R-PCECs) offer the potential for high-efficiency power generation and green hydrogen production at intermediate temperatures. However, the commercial viability of R-PCECs is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within conventional air electrodes operating at reduced temperatures. To address this challenge, this work introduces a novel approach based on the simultaneous optimization of bulk-phase metal-oxygen bonds and in-situ formation of a metal oxide nano-catalyst surface modification. This strategy is designed to expedite the ORR/OER electrocatalytic activity of air electrodes exhibiting triple (O2-, H+, e-) conductivity. Specifically, this engineered air electrode nanocomposite-Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95Ni0.05F0.1O2.9-δ demonstrates remarkable ORR/OER catalytic activity and exceptional durability in R-PCECs. This is evidenced by significantly improved peak power density from 626 to 996mW cm-2 and highly stable reversibility over a 100-h cycling period. This research offers a rational design strategy to achieve high-performance R-PCEC air electrodes with superior operational activity and stability for efficient and sustainable energy conversion and storage.

Seedless and electroless plating of silver on silica particles by using microreactor

Synthesis of silver nanoshells is still a challenge especially in the absence of surface modification of core particles and/or metal seed decoration on core surfaces. In this study, we applied a microrector to seedless and electroless plating of silver on bare silica particles, and investigated the effects of reaction temperatures and silver ion concentrations on the morphology and surface coverage of silver on the core particle surface. Our experiments demonstrated that the use of the microreactor enabled the one-step direct deposition of silver with a morphology close to complete shells and that silver ion concentrations from 0.2 to 0.5 mM at a moderate temperature of 50 °C produced high coverage and yield. Besides, the mixing sequence of NH3 and HCHO in the synthesis procedure was found to be a key factor to achieve the high silver coverage. In addition, we demonstrated that the addition of polyvinylpyrrolidone (PVP) after the silver shell growth reaction increases the stability without decreasing the reaction rate.

Cysteamine Chemisorption at Mercury-Solution Interfaces in the Context of Redox and Microdissociation Equilibria.

The redox behavior and chemisorption of cysteamine (CA) at a charged mercury surface are described, with an emphasis on its acid-base properties supported by molecular dynamics and quantum mechanical calculations. It was found that CA forms chemisorbed layers on the surface of the mercury electrode. The formation of Hg-CA complexes is connected to mercury disproportionation, as reflected in peaks SII and SI at potentials higher than the electrode potential of zero charge (p.z.c.). Both the process of chemisorption of CA and its consequent redox transformation are proton-dependent. Also, depending on the protonation of CA, the formation of typical populations of chemisorbed conformers can be observed. In addition, cystamine (CA disulfide dimer) can be reduced on the mercury surface. Between the potentials of this reduction and peak SI, the p.z.c. of the electrode used can be found. Furthermore, CA can serve as an LMW catalyst for hydrogen evolution. The mechanistic insights presented here can be used for follow-up research on CA chemisorption and targeted modification of other metallic surfaces.

PKa as a Predictive Descriptor for Electrochemical Anion Adsorption

AbstractThe adsorption of anions onto metal surfaces is important in many applications including effective (electro)catalyst design, metal surface modification, and contaminant removal in wastewater treatment. In electrocatalysis, anions can be both reactive intermediates or site‐blocking spectators, where their adsorption strength therefore dictates the rate of reaction. In this work, we have measured the adsorption energy of a series of carboxylic acids on a Pt (111) single‐crystal electrode surface from aqueous solution. We find that the adsorption strength of the carboxylate anion is linearly correlated with its acid‐dissociation constant (pKa) and therefore the heterolytic O−H bond dissociation strength in solution. Using density functional theory modeling, we split the anion adsorption energy into a sum of the adsorption energy and electron affinity of a neutral (carboxyl) radical. Surprisingly, the adsorption energy of the carboxyl radicals are similar and therefore the large difference in electron affinity is what dictates anion adsorption strength; the greater the cost in energy to remove the electron from the anion upon adsorption, the weaker its binding. Therefore, at least within a class of anions with similar structure and surface binding atoms, both electron affinity and acidity are predictive descriptors of adsorption strength.

PKa as a Predictive Descriptor for Electrochemical Anion Adsorption.

The adsorption of anions onto metal surfaces is important in many applications including effective (electro)catalyst design, metal surface modification, and contaminant removal in wastewater treatment. In electrocatalysis, anions can be both reactive intermediates or site-blocking spectators, where their adsorption strength therefore dictates the rate of reaction. In this work, we have measured the adsorption energy of a series of carboxylic acids on a Pt (111) single-crystal electrode surface from aqueous solution. We find that the adsorption strength of the carboxylate anion is linearly correlated with its acid-dissociation constant (pKa) and therefore the heterolytic O-H bond dissociation strength in solution. Using density functional theory modeling, we split the anion adsorption energy into a sum of the adsorption energy and electron affinity of a neutral (carboxyl) radical. Surprisingly, the adsorption energy of the carboxyl radicals are similar and therefore the large difference in electron affinity is what dictates anion adsorption strength; the greater the cost in energy to remove the electron from the anion upon adsorption, the weaker its binding. Therefore, at least within a class of anions with similar structure and surface binding atoms, both electron affinity and acidity are predictive descriptors of adsorption strength.

Surface modification of transition metals (TM: Mn, Fe, Co) decorated Pt-doped carbon quantum dots (Pt@CQDs) nanostructure as nonenzymatic sensors for nitrotyrosine (a biomarker for Alzheimer): Perspective from density functional theory

To develop a method for the detection of nitrotyrosine (NTS), transition metals: cobalt (Co), Iron (Fe), and Manganese (Mn) decorated Platinum-doped carbon quantum dot (Pt@CQDs) nanomaterial surfaces were computationally investigated. This study employed density functional theory (DFT) at the d3bj-B3LYP/def2SVP level of theory to gain in-depth knowledge of the adsorption, selectivity, reactivity, and trapping efficacy of nitrotyrosine (NTS) as a biomarker for Alzheimer disease. Results of the adsorption energy of the systems increased as −46.661 kcal/mol, −45.308 kcal/mol, −666.673 kcal/mol, and −12.507 kcal/mol which correspond to NTS_Co_Pt@CQDs, NTS_Fe_Pt@CQDs, NTS_Mn_Pt@CQDs, and NTS_Pt@CQDs. NTS_Mn_Pt@QDs system demonstrated the chemisorption as it has the highest adsorption energy. HOMO-LUMO analysis shows that cobalt decorated surface had the least energy gap of 1.586 eV while interaction with nitrotyrosine a decrease in the energy gap was observed particularly NTS_Pt@CQDs and NTS_Fe_Pt@CQDs exhibiting values of 1.850 eV and 1.665 eV respectively, whereas, Co_Pt@CQDs and Mn_Pt@CQDs systems showed drastic increase in the energy gap to 2.404 eV and 2.719 eV. This collective finding of this study is significant enough to present these systems as potential models for the detection and trapping of nitrotyrosine biomarkers for the diagnosis of Alzheimer's disease.

The decisive role of Au in CO diffusion on Pt surfaces: a DFT study.

The modification of metallic surfaces with adsorbed atoms of a second metal is presented as an ideal method for producing electrocatalysts. In this work, we examined the role of Au...

Advancements and Challenges in the Application of Metal-Organic Framework (MOF) Nanocomposites for Tumor Diagnosis and Treatment.

Nanoscale metal-organic frameworks (MOFs) offer high biocompatibility, nanomaterial permeability, substantial specific surface area, and well-defined pores. These properties make MOFs valuable in biomedical applications, including biological targeting and drug delivery. They also play a critical role in tumor diagnosis and treatment, including tumor cell targeting, identification, imaging, and therapeutic methods such as drug delivery, photothermal effects, photodynamic therapy, and immunogenic cell death. The diversity of MOFs with different metal centers, organics, and surface modifications underscores their multifaceted contributions to tumor research and treatment. This review is a summary of these roles and mechanisms. The final section of this review summarizes the current state of the field and discusses prospects that may bring MOFs closer to pharmaceutical applications.

Construction of superhydrophobic surfaces with different water adhesion on the low-temperature steels by picosecond laser processing

Manufacturing superhydrophobic metallic surfaces with desired water adhesion for intended applications such as anti-icing and microdroplets transportation remains a grand challenge. Herein, we demonstrated the fabrication of the superhydrophobic surfaces with different water adhesion on the low-temperature steels including DH36, EH40 and FH36 steels via combined strategies of picosecond laser processing and room-temperature vacuum processing. The laser processing could regulate the dimension of the micro/nanostructures on the low-temperature steel surfaces and the vacuum processing controlled the surface chemical compositions of the laser-processed surfaces, leading to the transition of wetting behaviors from the superhydrophilic states, then to the superhydrophobic Wenzel's states with strong water adhesion and finally to the superhydrophobic Cassie-Baxter's states with weak water adhesion. The superhydrophobic surfaces with the Wenzel's states showed great potential in non-destructive and selective transportation of water droplets, while those with the Cassie-Baxter's states exhibited promising anti-icing performance as well as desirable corrosion, impact, and erosion resistance. This work provides an effective, pollution-free, and stable route for controlling the superwettability of the low-temperature steel surfaces and could find promising applications in surface modifications of metals and alloys.

Uniform Zinc Plating Enabled By Polyimide Nanofiber Network for Long-Life Aqueous Zinc Metal Batteries

The rapid development of portable electronics and emerging electric vehicles has created a pressing need for electrical energy storage systems. Among these systems, zinc metal batteries (ZMBs) have shown great potential due to their high theoretical capacity density, low reduction potential, and low-cost anodes. However, the large-scale application of rechargeable ZMBs has been limited by the well-known issues of dendrite growth and adverse side reactions in zinc metal electrodes[1].Various strategies have been proposed to overcome the challenges associated with zinc dendrite growth, including substrate structure optimization, surface modification of zinc metal, and design of novel electrolytes. Among these approaches, constructing a protective layer on the zinc anode surface is a promising strategy due to its simplicity and cost-effectiveness. A dense polyamide coating layer, prepared by the doctor blading method, has been developed to regulate the aqueous Zn deposition behavior by elevating the nucleation barrier and restricting the 2D diffusion of Zn2+ ions [2]. Additionally, an Al2O3 coating layer has been developed using atomic layer deposition to improve the rechargeability of Zn anodes for zinc-ion batteries (ZIBs)[3]. However, these dense layers face a significant challenge to ionic conductivity due to the high energy barrier that hinders the diffusion of Zn2+ ions, leading to poor battery performance, especially under high current densities.Herein, we report utilizing an electrospun polyimide network (noted as PI-Zn hereafter) to resolve this dilemma. The polyimide (PI) chain has numerous carbonyl oxygen atoms that function as electron donors, supported by theoretical calculations (Fig.1). These atoms can establish stable bonds with Zn ions, thereby reducing the activation energy for de-solvation and enhancing the kinetics of Zn ion deposition. Unlike traditional coating methods, our electrospinning polymers form a fiber-like network structure that provides ion channels, thereby enhancing ion transportation. From the Nyquist plots of symmetrical batteries (Fig. 2), the PI-Zn electrode exhibits smaller charge transfer resistance and lower activation energy compared to the bare Zn electrode. The Transmission X-Ray Microscope results (Fig.3) reveal that the deposition on the bare Zn is heterogeneous and dendritic. In contrast, the PI-Zn electrode presented a smooth surface and dendrite-free morphology. The result demonstrates that the charge transfer ability, de-solvation, and deposition kinetics have been improved by PI-Zn, which further increases the plating uniformity.The stability of the Zn anode was evaluated by long-term galvanostatic cycling of a symmetrical Zn cell (Fig. 4). The cell with bare Zn failed after cycling for 100 h at a current density of 1 mA cm-2 resulting from the short circuit. In comparison, the cell with PI-Zn exhibits a stable polarization voltage and an ultralong cycling life of over 1200 hours, indicating the extremely reversible plating/stripping enabled by the PI network. Further interrogation of the PI-Zn was carried out by stringent deep-discharge tests in symmetrical Zn cells under extremely high current density and capacity of 20 mA cm-2 and 10 mA h cm-2. The result shows that the cell with PI-Zn can cycle for more than 200 hours, two times longer than that with bare Zn, proving the advantages of the unique fiber-like network structure, which provides fast and homogeneous Zn ion transportation. Moreover, the fiber network effectively suppresses the hydrogen evolution reaction, verified by the corrosion test, despite the existence of numerous ion channels.Full prototype cells were assembled to prove the practical applications of our strategy. Two promising cathodes for aqueous ZIBs, MnVOH and MnO2, in two different electrolyte systems (Zn(OTf)2 and ZnSO4) were coupled with bare Zn or PI-Zn. For both systems, the capacity retention and Coulombic efficiency are both significantly improved with the help of PI network. The results are consistent with the lifespan difference of symmetrical Zn cells, as expected due to the same plating and stripping processes on Zn. These findings demonstrate that the strategy presented here stands to both dramatically extend battery cycle life and boost battery performance, a promising approach to solve the anode issues in advanced Zn batteries. Cao, Z., et al., Advanced Energy Materials, 2020. 10(30): p. 2001599. Zhao, Z., et al., Energy & Environmental Science, 2019. 12(6): p. 1938-1949. He, H., et al., Journal of materials chemistry A, 2020. 8(16): p. 7836-7846. Figure 1

High Rate Performance of Li Metal Anode in Na-Containing so2-Based Inorganic Electrolyte

Lithium metal anode is one of the best candidates for the next generation energy storage systems due to the lowest electrochemical potential (- 3.04 V vs. standard hydrogen electrode) and the highest theoretical capacity (3860 mAh g-1). However, lithium metal anode have critical problems including dendritic growth of Li deposits during cycling, poor stability of solid electrolyte interface (SEI) on lithium metal anode and severe chemical reaction between Li metal and the electrolyte. Recently, stable artificial interface layers on the Li metal anode have been proposed to solve these problems. In this work, surface modification of Li metal with a Na-containing SO2-based inorganic electrolyte was investigated as an effective way to prevent lithium dendritic growth during cell operation. The surface-modified lithium metal anode effectively prevented the dendritic deposits of Li deposits even at high current density (3 mA cm-2). More detailed reaction chemistry of Li metal with Na-containing inorganic electrolyte will be discussed in the presentation.

Revisiting a Cu-rich layer on the aluminum surface after twin-jet electropolishing

Twin-jet electropolishing (TJE) is a well-known method to prepare Cu-containing Al alloys for transmission electron microscopy (TEM) observation. Previous studies have reported a Cu-rich layer usually formed between Al matrix and outermost alumina layer at the electropolished Al surface. However, characteristics and formation mechanisms of the Cu-rich layer remain largely unexplored. Herein, configurations, formation process and property of the Cu-rich layer formed during TJE of Al alloys are revealed detailly employing aberration-corrected scanning TEM (STEM), STEM image simulations and first-principles calculations. The results reveal a new orientation relationship between the Cu-rich layer (θ’-Al2Cu) and Al matrix, which produces a low interfacial Al strain field. Formations of ∼2-nm-thick θ’ layer and its beneath ∼6-nm-thick Cu diffusion zone at the electropolished Cu-containing Al surface are mainly associated with traces of Cu in the electrolyte and anodization. Selective oxidation of elements, Cu-emitting alumina layer and spontaneous solute Cu segregation at the Al surface are also responsible for formations of the θ’ layer and Cu diffusion zone. Further study reveals that the θ’ layer behaves a strong self-healing ability after damaged by high-energy electron beam. The obtained results provide a potential insight into the surface modification of metals and alloys using electrochemical method.

Rational surface modification of zirconium-based metal–organic framework nanomaterials for the adsorption and recovery of coloured drugs and proteins from aqueous solutions

Coloured drugs and proteins in pharmaceutical wastewater cause environmental pollution. Metal–organic frameworks (MOFs) can be used for the adsorption and recovery of pollutants from wastewater, however selective adsorption and desorption on MOFs are challenging. Herein, UiO-66 and various polyethylene glycol (PEG)-modified MOFs (UiO-66 @mPEG-PO3 and UiO-66 @DSPE) were synthesised to selectively adsorb and separate model drugs [curcumin (CUR) and myricetin (MYR)] and proteins [Bovine serum albumin (BSA) and ovalbumin (OVA)]. Results show that UiO-66 adsorption efficiency for CUR and MYR in aqueous solution reached 93% and 98%, respectively. Additionally, CUR and MYR adsorbed on the UiO-66 surface exhibit good antioxidant activity during the recycling process. X-ray photoelectron spectroscopy and Hirshfeld surface analysis indicate that the adsorption mechanisms of both CUR and MYR by UiO-66 are belonging to the intermolecular interactions. The UiO-66 @mPEG-PO3 significantly reduces the surface area of UiO-66 (216 m2/g) but does not alter the adsorption behaviour of drugs. In the process of desorption and separation of CUR and MYR, the UiO-66 @PEG-PO3 exhibits a higher desorption rate than UiO-66. By contrast, the UiO-66 @DSPE MOFs exhibits optimal protein adsorption and selectively enhances the desorption of OVA rather than BSA in a 40% acetonitrile solution. This method can be used to capture and detect OVA proteins in cell lysates. Rational surface modification is an effective way to improve the adsorption selectivity and recovery efficiency of zirconium-based MOFs, providing an effective way to use MOFs in treating novel water pollutants.

Characteristics of plasma electrolytic oxide coating on magnesium-hydroxyapatite composites

Plasma electrolytic oxidation (PEO) is a surface modification of metals to grow a ceramic-like oxide coating with remarkably enhanced corrosion resistance. This work studies the characteristics of the PEO coating formed on magnesium-hydroxyapatite (Mg-HA) composites with HA concentrations of 0, 10, 20, and 30 wt% prepared by spark plasma sintering (SPS). Thin PEO coatings of 1–3 μm were successfully formed on all specimens in 0.5 M Na3PO4 electrolyte for 5 min. The plasma became finer, reducing the pore size and thickness, with increasing HA concentration. Agglomeration of HA particles in Mg-20HA and Mg-30HA inhibited coating coverage. EDS and XRD analyses confirmed the similar composition of Mg3(PO4)2 in all the coatings. The coating improved surface wettability and showed high apatite-forming ability in simulated body fluid. The optimum coating performance was obtained for Mg-10HA.

An examination and prospect of stabilizing Li metal anode in lithium–sulfur batteries: A review of latest progress

AbstractThe Li metal anode emerges as a formidable competitor among anode materials for lithium–sulfur (Li‐S) batteries; nevertheless, safety issues pose a significant hurdle in its path toward commercial viability. This review enumerates three historical challenges inherent to the Li metal anode: unavoidable volume expansion, multifunctional solid electrolyte interface formation, and uncontrollable lithium dendrite growth. In particular, when paired with a sulfur cathode, the Li anode presents an additional unique hurdle: the shuttle effect. To address these issues, this article offers a thorough examination of the latest innovations aimed at stabilizing the Li metal anode within Li‐S batteries. We categorize these approaches into five classifications: liquid electrolyte optimization, enhancement of non‐liquid‐state electrolytes, Li metal surface modification, Li anode architecture design, and Li alloy improvement. For several noteworthy results within these categories, we have compiled their electrochemical performance into tables, facilitating direct comparison. This detailed analysis illuminates feasible strategies and suggests directions warranting further exploration for optimizing the capability and safety of Li metal anodes in Li‐S batteries.