XPS Surface Analysis Research Articles

The use of amines as steel corrosion inhibitors in butanol-gasoline blends

Butanol is an interesting component used for blending gasoline fuels. However, the polar nature of butanol allows the solubility of water and ionic compounds in butanol-gasoline blends (BGBs) making them aggressive to mild steel. Amines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentaamine, morpholine, piperazine, and hexamethylenediamine, were tested as corrosion inhibitors for mild steel in BGBs. Additionally, the influence of the acetic acid and sodium chloride concentrations on the inhibition efficiency was examined. Electrochemical impedance spectroscopy andpotentiodynamic polarization were employed for the measurements, complemented by static immersion testing and an XPS surface analysis. The highest inhibition efficiency was demonstrated for diethylenetriamine, triethylenetetramine, andhexamethylenediamine, achieving a value of 95 % or more at aconcentration of 100 mg/L. The formation of ionic pairs involving protonated amines andchlorides was also confirmed. The XPS analysis revealed a very thin passive layer of iron oxides, which may form in the presence of amines, protecting mild steel in BGBs.

Ternary photocatalyst of Fe3O4/Ag-SnO2 with Parkia speciosa extract improves visible-light-driven photocatalytic degradation of dye

SnO2 is a highly utilized and cost-effective photocatalyst in various industries, including industrial polishes, glass and ceramic coatings, building materials, and gas sensor systems. However, the light emission process has limitations due to the rapid recombination of electrons and holes. In order to overcome this issue, an innovative study was conducted in which a cheap and non-toxic plant extract precursor with phytochemicals was used as a capping agent. Fe3O4/Ag-dopedSnO2 nanocomposites with varied Ag and SnCl2 ratios were synthesized, and the samples were characterized using FTIR, UV–visible, XRD, SEM, TEM, XPS, and BET surface analyses. Adding Ag to the nanocomposites slowed down the recombination of charge carriers. This made Fe3O4/Agx-SnyO2 (x:y = 1:1, 1:3, 3:1) a better photocatalyst than Fe3O4 or SnO2 alone. Rhodamine B, a model pollution dye, was decomposed under 50 W LED light to test the efficiency of the as-synthesized nanocomposite photodecomposition. When illuminated with LED light, the Fe3O4/Agx-SnyO2 (FAS3) (x:y=3:1) nanocomposite displayed increased photocatalytic activity. These results showed that excited charge electrons from SnO2 could move to the Ag conductive band to speed up charge pair separation. This would make the photocatalysis of Ag-doped SnO2 more effective at breaking down dye.

Novel Electrolyte Development for In Situ Formed Li-Metal Batteries Using Amplified Solid Electrolyte Interphase and Plating Investigations

Li-metal anodes can provide high energy density battery configurations, but their practical use is hindered by safety concerns and poor efficiencies due to non-ideal lithium plating. In utilizing ultra-low areal plating capacities (0.08 mAh cm−2, LCP) within Li-metal half-cells, it was found that the initial formation efficiency of the SEI can be amplified and correlated with initial losses and capacity fade over time under higher areal plating capacities (2.5 mAh cm−2, 4.0 mAh cm−2, and 6.5 mAh cm−2) within an in-situ formed anodeless LCO configuration. Herein, these techniques have been utilized to introduce and optimize novel fluoroganosiyl (FOS) based dual salt electrolytes for use in in-situ formed Li-metal batteries, achieving initial cycling loss of <3% (at 4.0 mAh cm−2). Further characterization of the functional benefit of this electrolyte was elucidated using XPS surface analysis, revealing unique Li-C-N, Li3N, Si, and B-N chemistries that likely contribute to the formation of a robust SEI.

Structural, electronic, and magnetic study on hematite nanorods: Effect of carbon coating and annealing temperature

In this work, spindle shape α-Fe2O3 nanorods and carbon-coated α-Fe2O3@C nanorods were synthesized using a simple hydrothermal method followed by calcination at a temperature of 600 °C. Morphology, structural, surface, and magnetic properties of the synthesized samples were studied before and after calcination. XRD results prove the formation of a single corundum phase α-Fe2O3 after hydrothermal preparation at 180 °C. The crystallite size of α-Fe2O3 decreases by calcination in contrast with α-Fe2O3@C. Through calcination, meso-size pores were formed as investigated by TEM. These pores are more in α-Fe2O3 nanorods. Using XPS surface analysis, more O-H bonds were found in α-Fe2O3 nanorods. TEM, XPS, and FTIR techniques were used to prove the formation of the Carbon layer on α-Fe2O3@C nanorods. Intensive characterization and the magnetic properties of α-Fe2O3 and α-Fe2O3@C nanorods were also carried out and reported. VSM measurements show an increase in magnetic moment with smaller coercivity and remanence via C-coating and calcination. The Morin transition as investigated using VSM and Mossbauer measurements, appears for pure hematite nanorods after calcination under atmospheric pressure. This transition is suppressed as shown for nanosize particles with c/a of ≥ 2.74 which was also applicable for samples made by other workers.

Surface Engineering of GaN Photoelectrode by NH3 Treatment for Solar Water Oxidation

&lt;p&gt;Photoelectrochemical (PEC) water splitting is a vital source of clean and sustainable hydrogen energy. Moreover, the largescale H&lt;sub&gt;2&lt;/sub&gt; production is currently necessary, while long-term stability and high PEC activity still remain important issues. In this study, a GaN-based photoelectrode was modified by an additional NH&lt;sub&gt;3&lt;/sub&gt; treatment (900°C for 10 min) and its PEC behavior was monitored. The bare GaN exhibited a highly crystalline wurtzite structure with the (002) plane and the optical bandgap was approximately 3.2 eV. In comparison, the NH&lt;sub&gt;3&lt;/sub&gt;-treated GaN film exhibited slightly reduced crystallinity and a small improvement in light absorption, resulting from the lattice stress or cracks induced by the excessive N supply. The minor surface nanotexturing created more surface area, providing electroactive reacting sites. From the surface XPS analysis, the formation of an N-Ga-O phase on the surface region of the GaN film was confirmed, which suppressed the charge recombination process and the positive shift of E&lt;sub&gt;FB&lt;/sub&gt;. Therefore, these effects boosted the PEC activity of the NH&lt;sub&gt;3&lt;/sub&gt;-treated GaN film, with &lt;italic&gt;J&lt;/italic&gt; values of approximately 0.35 and 0.78 mA·cm&lt;sup&gt;−2&lt;/sup&gt; at 0.0 and 1.23 V&lt;sub&gt;RHE&lt;/sub&gt;, respectively, and an onset potential (V&lt;sub&gt;on&lt;/sub&gt;) of −0.24 V&lt;sub&gt;RHE&lt;/sub&gt;. In addition, there was an approximate 50% improvement in the &lt;italic&gt;J&lt;/italic&gt; value within the highly applied potential region with a positive shift of V&lt;sub&gt;on&lt;/sub&gt;. This result could be explained by the increased nanotexturing on the surface structure, the newly formed defect/trap states correlated to the positive V&lt;sub&gt;on&lt;/sub&gt; shift, and the formation of a GaO&lt;sub&gt;x&lt;/sub&gt;N&lt;sub&gt;1-x&lt;/sub&gt; phase, which partially blocked the charge recombination reaction.&lt;/p&gt;

Assessment of Microstructural, Mechanical and Electrochemical Properties of Ti-42Nb Alloy Manufactured by Electron Beam Melting.

The β-type Ti-42Nb alloy has been successfully manufactured from pre-alloyed powder using the E-PBF method for the first time. This study presents thorough microstructural investigations employing diverse methodologies such as EDS, XRD, TEM, and EBSD, while mechanical properties are assessed using UPT, nanoindentation, and compression tests. Microstructural analysis reveals that Ti-42Nb alloy primarily consisted of the β phase with the presence of a small amount of nano-sized α″-martensite formed upon fast cooling. The bimodal-grained microstructure of Ti-42Nb alloy comprising epitaxially grown fine equiaxed and elongated equiaxed β-grains with an average grain size of 40 ± 28 µm exhibited a weak texture. The study shows that the obtained microstructure leads to improved mechanical properties. Young's modulus of 78.69 GPa is significantly lower than that of cp-Ti and Ti-6Al-4V alloys. The yield strength (379 MPa) and hardness (3.2 ± 0.5 GPa) also meet the criteria and closely approximate the values typical of cortical bone. UPT offers a reliable opportunity to study the nature of the ductility of the Ti-42Nb alloy by calculating its elastic constants. XPS surface analysis and electrochemical experiments demonstrate that the better corrosion resistance of the alloy in SBF is maintained by the dominant presence of TiO2 and Nb2O5. The results provide valuable insights into the development of novel low-modulus Ti-Nb alloys, which are interesting materials for additive-manufactured implants with the desired properties required for their biomedical applications.

Construction of Pd-Co-doped CdS heterojunctions as efficient platforms in photocatalysis.

In this work, we present the structural, optical and photocatalytic properties of CdS semiconducting nanostructures, doped with palladium- and cobalt-based species. XRD analysis, corroborated by Raman and XPS, demonstrated the growth of CdS crystallites in the hexagonal structure, whereas solvothermal conversion of neat precursor metal salts resulted in the formation of metallic Pd and cobalt oxide, respectively. Scanning electron microscopy imaging certified the dendritic structure of hybrids, especially in the case where CdS was grown in the presence of either palladium- or cobalt-based nanoparticles. XPS surface analysis revealed that a major fraction of metallic Pd nanoparticles was converted to PdO during the in situ growth of CdS nanoparticles. The oxidation of Pd nanoparticles could be ascribed to chemisorption of oxygen phases onto the metal surface. The presence of cocatalyst nanoparticles resulted in an appreciable shift of the absorption edge of the ternary hybrids by about 50 nm. The optimized hybrid was found to photodegrade Orange G dye almost quantitatively within 2 h, by simulated solar light irradiation. Scavenging experiments revealed that hydroxy radicals were the main transient intermediate, leading to the oxidative degradation of the dye.

Synthesis of a siloxane oligomer containing methyl acryloxy group for promoting the adhesion of addition-type silicone rubber to copper plate

An adhesion promoter containing methyl acryloxy group was synthesized according to a non-hydrolysis sol-gel method with methyl phenyl silicone oil containing hydroxyl terminal group, methyl vinyl dimethoxy silane, and γ–methyl acryloxy propyl methyl dimethoxy silane (KH572) as raw materials and then applied in an addition-type silicone rubber. The structure of the product was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectrum (1H NMR). In addition, scanning electron microscope (SEM), mechanical testing machine and video-based optical contact angle measuring instrument were used to test its performance. We found that the adhesion promoter largely improved the bonding performance of the addition-type silicone rubber and showed the better compatibility with liquid silicone resins. When the amount of the adhesion promoter was 2.0 phr, the shear strength between silicone rubber and copper plate reached 1.33 MPa. The optical performance test results indicated that the light transmittance of silicone rubber was slightly changed when the addition amount of the adhesion promoter was no more than 2.0 phr, and this met the encapsulation requirements of electronic packaging adhesives. The contact angle test results indicated that the adhesion promoter reduced the static contact angle between the liquid silicone rubber and copper plate surface and improved the wettability. In addition, oxidation experiments, thermal resistance experiments, SEM tests and XPS surface analysis preliminarily proved that the adhesion promoter could significantly enhance the adhesion via chemical bonds formed with both the cured silicone rubber and the surface of copper plate substrate.

Corrosion Behavior of High-Strength C71500 Copper-Nickel Alloy in Simulated Seawater with High Concentration of Sulfide

The corrosion behavior of high-strength C71500 copper-nickel alloy in high concentrations of sulfide-polluted seawater was studied by potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS), immersion testing, and combined with SEM, EDS, XPS, and XRD surface analysis methods. The results showed that the C71500 alloy shows activation polarization during the entire corrosion process, the corrosion rate is much higher (0.15 mm/a) at the initial stage of immersion, and the appearance of diffusion limitation by corrosion product formation was in line with the appearance of a Warburg element in the EIS fitting after 24 h of immersion. As the corrosion process progressed, the formed dark-brown corrosion product film had a certain protective effect preventing the alloy from corrosion, and the corrosion rate gradually decreased. After 168 h of immersion, the corrosion rate stabilized at about 0.09 mm/a. The alloy was uniformly corroded, and the corrosion products were mainly composed of Cu2S, CuS, Cu2(OH)3Cl, Mn2O3, Mn2O, MnS2, FeO(OH), etc. The content of Cu2S gradually increased with the extension of immersion time. The addition of S2- caused a large amount of dissolution of Fe and Ni, and prevented the simultaneous formation of a more protective Cu2O film, which promoted the corrosion process to some extent.

XPS Surface analysis augmented using correlative spectroscopy and microscopy

XPS Surface analysis augmented using correlative spectroscopy and microscopy

Micro Raman and XPS surface analysis to understand the electrochemical behaviour of AZ31 and AZ91 magnesium alloys as temporary implant materials.

Degradable metals and alloys have a potential use for surgical orthopedic applications. In this work, surface oxide/hydroxides formed by degradation, are evaluated in two commercial magnesium alloys (AZ31 and AZ91 alloys) by Raman, electrochemical and X-ray spectroscopic techniques. Electrochemical and surface/composition characterization of the AZ31 and AZ91 alloys are developed in contact with Hanks‘ Buffered Salts Solution (HBSS) at 37 °C. AZ31 alloy shows lower corrosion resistance than AZ91 in HBSS at 37 °C, both for short (24 h) and long (17 days) periods of immersion. The surface analysis demonstrate that on both alloys there are abundant corrosion products and the presence of compounds related to apatite. These results show that layers of magnesium oxide and hydroxide can be formed on the alloys surfaces, which gives them a certain degree of protection. The simulated body fluids contain different amounts of Ca2+ ions, carbonates / bicarbonates and phosphates, in addition to the Mg2+ ions (and other cations such as Al3+ and Zn2+) coming from the biomaterial corrosion environment. Thus, specific surface conditions can vary, such as the local pH value, and different corrosion products can precipitate which have different substrate protection properties. These corrosion products can slow down the degradation and influence the adsorption of proteins and cellular adhesion to the Mg surface by changing its chemistry and topography. The use of compositional (Raman and X-ray spectroscopies) and electrochemical (EIS and polarization curves) techniques, allows to do generate advances in the surface and degradation knowledge of typical Magnesium alloys like AZ31 and AZ91, for possible use as temporary implants. Even the analysis was carried out under static conditions, the systematic approach done is complete to picture the degradation mechanism of these alloys. Flow laboratory experiments are consider important to include as future work.

Aluminum anodizing with simultaneous silanization for increased hydrophobicity and corrosion protection

Anodizing and deposition of hydrophobic films are processes used separately to improve the atmospheric corrosion resistance and hydrophobicity of Al alloys used for heat exchangers. In the present work, we assessed the effect of various additives on the sulfuric acid anodizing (SAA) electrolyte, namely ethanol, trifluoroethanol, hexadecyltrimethoxysilane (HDTMS), and perfluorooctyltriethoxysilane (PFOTES). By tailoring the anodizing process, simultaneous growth of a protective porous layer and hydrophobicity increase of AA1100 were achieved in one step. Cell potential transients and XPS surface analysis confirm that silane incorporation into the oxide structure during anodizing enhances the hydrophobic properties of samples anodized in SAA-ethanolic PFOTES electrolytes. When HDTMS is added, a uniform hydrophobic protective coating is produced, but the electrolyte is unstable. The time required for nucleation of pitting corrosion in potentiostatic tests in NaCl increases when ethanol, HDTMS, or PFOTES are incorporated in the anodization bath.

Reactivity passivation of red phosphorus with thin plasma-deposited carbon coating

Red phosphorus, when exposed to humid environments in air, breaks down into toxic phosphine gas and acidic phosphorus species, presenting a challenge for many applications, such as flame retardants or pyrotechnic obscurants. We have developed and characterized a method of plasma-deposited carbon to form a nanometer-thick, chemically stable carbon layer on red phosphorus particles to suppress phosphine and acidic phosphorus production. Using a combination of XPS surface analysis and a novel IR headspace analysis method, we developed and quantified an understanding of the reaction of red phosphorus with water vapor and the suppression of decomposition products using plasma-deposited carbon coatings. Phosphine production, quantified by IR, was accompanied by the formation of surface POx species produced as the particles react with water vapor. Increasing plasma deposition time increased thickness and uniformity of graphitic carbon coating, corresponding to a marked decrease in phosphine generation and formation of surface POx species.

Effect of nitrogen content on structural and mechanical properties of AlTiZrTaHf(-N) high entropy films deposited by reactive magnetron sputtering

There is a growing interest in the design of high entropy alloys due to their remarkable properties and applications in various fields such as aerospace, medical and automotive. AlTiTaZrHf(-N) high entropy metal-sublattice nitrides were deposited in various argon‑nitrogen gas mixtures on glass and silicon substrates. X-ray diffraction analyses reveal a transition from amorphous to an FCC single phase by increasing the nitrogen content. The films have compact or columnar morphology depending on the nitrogen flow rate. Energy dispersive spectroscopy analysis shows a decreasing of the matals content as the nitrogen flow rates ratio R N2 = N 2 /Ar + N 2 increases. XPS surface analysis reveal the formation of nitrides when the nitrogen is introduced. Evolution of hardness and Young's modulus are discussed and the maximum values are obtained for a flow rates ratio R N2 of 10% at 27.67 GPa and 205.56 GPa respectively. The same film reveals good tribological properties compared to other films. This work conclusively demonstrates that high entropy metal-sublattice nitrides can be generated in an efficient way with tunable properties. • Multicomponent AlTiTaZrHf(-N) deposited by reactive magnetron sputtering • Effect of nitrogen content on microstructure, mechanical properties and tribological performance studied • H and E are monitored by controlling the stoichiometric of N/Me.

Copper-Based Alloys as Anti-Viral High-Touch Surfaces: An Investigation of Kill Efficiency and Mechanism in a Simulated Hospital Environment

The route of transmission of SARS-CoV-2 remains a key concern during the COVID-19 pandemic. One highly important route of transmission is from infected host to fomite surface to a novel host. The purpose of this work is to assess the performance of copper-based alloys as anti-viral materials for high-touch surfaces in terms of virus survivability when exposed to a simulated hospital environment. Upon exposure of such a surface to an electrolyte, such as human perspiration, copper ions and reactive oxygen species are produced via electrochemical reactions, and each are thought to play a role in virus mitigation. The reactions involved, and the fate of copper, depend on alloy composition and the details of surface structure, morphology and the nature of the passive oxide surface film. The oxide film can be severely affected by the environmental conditions to which it is exposed, for example, regular treatment with cleaning products, particularly those containing chlorides. The current work aims to elucidate the mechanism by which the oxide film impacts the efficacy of virus mitigation, though utilization of electrochemical corrosion testing and surface analysis techniques.The current study presents data for the anti-viral performance of Pure Cu and a Cu-30Ni alloy against Human-Coronavirus HuCoV-OC43, a representative strain of a prototypical coronavirus. The study was conducted as a function of periodic exposure to two common cleaning products, namely: (1) bleach and (2) a glutaraldehyde-based solution, for a four-week period. These are compared to surfaces where no cleaning solution was applied. Kill tests were performed by applying a droplet of assay media, carrying the HuCoV-OC43 virus, to the relevant surfaces. Droplet exposure times were systematically increased, up to a maximum of 1 hour, for a kill-rate to be established for each surface. Electrochemical experiments and xps surface analysis, conducted after immersion in artificial perspiration for either 10 minutes or three days, provide information regarding the corrosion rate and kinetics and the nature of the surface oxide film, respectively, for specimens exposed to each of the conditions described.This work will be vital for the immediate selection of specific copper alloys for deployment as high-touch surfaces, and enable future development of alloys further optimized for this function. The presented work will provide an understanding of the corrosion behavior of copper-based alloys in human touch environments, rooted in an understanding of surface chemistry and oxides as well as their potential for mitigating virus transmission. Furthermore, the work aims to demonstrate the application of such metallic coatings for protection against transmission of COVID-19 and future viral diseases as well as revealing the details of copper alloy corrosion mechanisms in a human environment.

Problems in XPS Surface Analysis Community Worldwide

Problems in XPS Surface Analysis Community Worldwide

The effects of support morphology on the performance of Pt/CeO2 catalysts for the low temperature steam reforming of ethanol

A series of Pt/CeO2 catalysts with different support morphologies was studied for the low temperature ethanol steam reforming. Different ceria nanostructures (nanocube_NC, nanorod_NR and flower-like_FL) were prepared by the hydrothermal method and are compared with CeO2 obtained by precipitation. Support morphology was found to influence certain reaction routes, even though the reaction scheme was the same regardless of the support. Concerning catalyst stability at 573 K, Pt/CeO2- PPT exhibited rapid deactivation, whereas Pt/CeO2- NR remained rather stable. XPS surface analysis before and after reaction at 573 K revealed significant degree of Pt reduction on CeO2 nanorods, directly related to the reduction of Ce4+ into Ce3+. DRIFTS experiments under reaction conditions for 5 h, revealed an accumulation of acetates on the Pt/CeO2- PPT catalyst, likely due to the imbalance between the rate of acetate species decomposition to CHx (not facilitated over Ptδ+ of the catalyst with the lower Pt dispersion), and their desorption as CH4.

Pulse potential method-assisted construction and regulation of a trivalent chromium conversion coating on hot-dip coated steel sheet

A pulse potential method (PPM) was used to regulate the formation of Cr(III) conversion coating (TCC) on hot-dip Zn-55 % Al-1.6 % Si. The micromorphology analysis and the contact angel measurement showed that the application of PPM changed the micro-features and hydrophobicity on the surface of TCC. Surface XPS analysis indicated that PPM increased the proportion of hydroxides and greatly reduced the content of Cr(VI) on TCC. Better corrosion resistance of the TCC was measured using multiple electrochemical methods when the pulse square-wave potential Ep = −0.10 V. The results corroborated the positive role of PPM in improving the temporary corrosion resistance of hot-dip coating.

XPS and AES surface analysis of WC‐Co‐(Cr) cemented carbide after immersion in neutral solution

The binder phase Co in WC‐Co cemented carbide is dissolved easily in corrosive media (even in neutral solution), which has limited its application in a wider range. In this paper, the influence of Cr on corrosion resistance of WC‐Co immersed in neutral solution was studied, with a focus on the surface chemistry of the corrosion product. The results show that in neutral solution, the corrosion is mainly caused by the selective dissolution of Co and the dominant surface corrosion product after immersion is Co (OH)2. The corrosion resistance of WC‐Co cemented carbide can be improved by the addition of Cr. This can be explained by the formation of more protective chromium containing oxide on the binder phase of WC‐Co‐Cr alloy, leading to reduced corrosion rate.

Materials studies of copper oxides obtained by low temperature oxidation of copper sheets

Inexpensive and stable solar cells based on oxide materials are currently strongly investigated. The surest candidates are copper oxides, which unlike to other metal oxides display strong absorption across the visible range. Although, copper oxides thin film can be deposited by the number of methods, cost effective techniques applicable for large scale production are necessary. Therefore, the main focus of this paper was turned to the simple and time effective thermal oxidation of copper sheets using relatively low temperatures 200–400 °C. The surface pretreatment was selected in order to support homogeneous growth conditions. The basic material research presented here included the morphological, compositional and microstructural aspects of grown copper oxides. The surface roughness of manufactured layers for investigated temperature range was described either by AFM microscopy where Ra was assessed between 8.9 and 67.6 nm and also by the optical method where calculated haze factor ranged from 34 to 79.3%. Microstructure and phase composition studies were performed by means of TEM and XRD supplemented by XPS surface analysis confirming the dominating phase of copper (I) oxide capped with thin surface CuO layer. Finally, the optical properties were described allowing to determine the sample absorptivity and band gap energy varying in the range 2.43–1.93 eV.