The presence of adventitious carbon on samples analysed by X-ray photoelectron spectroscopy can complicate data interpretation. Because adventitious carbon can contain a significant amount of oxygen-containing functional groups, accounting for its contribution is essential when analysing oxygen. For example, accurately determining the oxygen concentration-free from adventitious carbon contributions-is often crucial for some data interpretation. Additionally, when modelling high-resolution oxygen 1s spectra, the organic oxygen must be considered to ensure accurate interpretation. Although these aspects of data interpretation should ideally be guided by stoichiometry, the process can be tedious and challenging, particularly for novice users. This Insight Note introduces a method for accounting for organic oxygen associated with adventitious carbon. It provides background information, outlines key assumptions and includes an easy-to-use Excel calculator to support this analysis, making the approach more accessible, especially for novice users.

Magnesium-copper alloys offer antimicrobial properties and improved mechanical performance due to Cu addition, which is advantageous in making anastomoses and anastomotic nails. For such applications, a controllable degradation of Mg-Cu alloys inside the human body is desired. This study investigates the surface morphology and chemistry of Mg-xCu alloys with varying Cu loadings x% (with x = 0.2, 0.6, 1.0 and 1.5) after immersion in aerated Hank's balanced salt solution at 37 degrees C, which simulates a physiological environment. Profilometry and time-of-flight secondary ion mass spectrometry analyses reveal that Mg-0.2Cu forms a corrosion-preventing layer of calcium phosphate and calcium hydroxide, while higher Cu loadings result in increased surface roughness and void, suggesting increased corrosion rates. Despite morphological differences among Mg-0.6Cu, Mg-1.0Cu and Mg-1.5Cu, their surface chemistry is characteristic of magnesium hydroxide. Electrochemical impedance spectroscopy confirms the corrosion resistance of Mg-0.2Cu and higher corrosion rates for other alloys. These findings suggest that Cu loading regulates the corrosion rates of Mg-Cu alloys, providing insights into controlling their biodegradation for medical applications.

Metal powders are crucial precursors for manufacturing surfaces through thermal spraying, cold spraying, and 3D printing methods. However, surface oxidation of these precursors poses a challenge to the coherence of the metallic materials during manufacturing processes. Herein, we introduce a method for surface modification of copper powder with N-heterocyclic carbenes (NHCs) using mechanochemistry to mitigate surface oxidation. A resonant acoustic mixer was used to deposit five different carbenes on copper powders using benzimidazolium hydrogen carbonate precursors and a trace amount of solvent. Significant oxide reduction was observed by X-ray photoelectron spectroscopy (XPS), and the immobilization of NHCs on the powder was confirmed by mass spectrometry and XPS. The consistent morphology of the modified copper powder minimizes any potential impact on subsequent manufacturing processes. Moreover, a life cycle assessment indicates the potential environmental hotspots, leading to recommendations to develop lower-footprint processes. Overall, the mechanochemical method to produce NHC-modified metal powders with a higher metallic content provides great prospects for powder precursors to produce coatings from thermal spray, cold spray, and additive manufacturing processes.

The effect of chloride on the corrosion mechanism of copper in deaerated, 0.1 M HNO3 was studied by electrochemistry, atomic force microscopy, and scanning electron microscopy. Nitrate reduction, the first cathodic step in the corrosion pathway, was completely inhibited in the presence of ppm levels of chloride, thereby shutting down the corrosion sequence of the system involving solution reactions by copper ions and the subsequent reduction of NO2-. Nitrite reduction was minimally affected, suggesting that the two reduction steps differ substantially in their sensitivity to the surface state during corrosion. Our results support the proposal that the key step responsible for the inhibitive effect of chloride is the adsorption of chloride to form an adlayer on the surface. Nitrate reduction on copper appears to be inhibited by chloride in the presence of corrosion accelerators, NO2 - and Cu+/Cu2+, which suggests that the chloride adlayer remains intact under more aggressive conditions and lowers the rate of corrosion from nitrate reduction in the presence of other oxidants.

X-ray photoelectron spectroscopy (XPS) is a frequently employed technique for surface characterization, particularly useful in studying self-assembled monolayers (SAMs). Herein, we examine precursors and SAMs of N-heterocyclic carbenes (NHCs) on gold. We establish a reliable and reproducible XPS peak-fitting model for 1,3-diisopropyl-1H-benzo[d]imidazol-3-ium hydrogen carbonate and its CF3-tagged derivative to enable accurate detection, quantification, and chemical analysis of NHCs by XPS. The effects of molecular architecture variations on the N 1s peak were investigated and found to be insignificant across a wide range of derivatives. The characteristics of the N 1s peak after deposition on a gold surface were examined. All samples show a symmetric N 1s peak centered around 400.5 eV, with a FWHM ranging from 1.2 to 1.6 eV, which is a 0.6 eV shift compared to the starting hydrogen carbonate precursors, or other salts, which appear at 401.1 eV. Examination of hydrogen carbonate salts during extended irradiation under ultrahigh vacuum illustrates that dehydration and eventually decarboxylation likely take place during the process of measuring the XP spectra. More substantial degradation of the precursors can be observed after 4 h of exposure to the conditions of measurement for simple NHC precursors, with the CF3-tagged NHC salts degrading more rapidly within 2 h due to C-F bond cleavage. Common impurities that may result from synthetic conditions and can complicate the N 1s spectra are also presented.

Achieving high capacity, long-term stability, and fast charge-discharge capability remains a central challenge in the development of advanced anode materials for lithium-ion batteries. In this work, we present nickel vanadium oxyphosphide (NVOP) nanosheets synthesized via controlled thermal phosphorization of NiV-layered double hydroxide (NiV-LDH). The resulting multiphase structure, composed of conductive Ni2P and redox-active vanadium oxides, delivers an initial discharge capacity of 1345 mAh/g and retains 442 mAh/g after 200 cycles at 0.1 A/g, with Coulombic efficiency stabilizing near 99.5%. NVOP also demonstrates excellent rate performance, maintaining 359 mAh/g at a high current density of 1.0 A/g. Electrochemical and structural characterization suggest that the improved cycling stability and rate capability may stem from the multiphase architecture, which integrates conductive and redox-active components within a porous nanosheet framework. These findings underscore the potential of direct phosphorization of mixed-metal layered hydroxide precursors as an effective strategy for constructing high-performance, durable anode materials for next-generation lithium-ion batteries.

Copper powder is essential in the thermal spray industry for its excellent thermal and electrical conductivity. However, uncontrolled surface oxide on Cu powder degrades coating performance by weakening inter-particle bonding. This study introduces a novel method using N-heterocyclic carbene (NHC) chemistry to remove surface oxides from Cu powder via a one-pot immersion process. NHC functionalization not only eliminates surface oxides but also acts as a capping agent, enhancing the corrosion resistance of the sprayed coatings. Detailed investigations using scanning electron microscopy, X-ray photoelectron spectroscopy, and laser desorption/ionization spectroscopy confirmed the successful NHC treatment. The process was scaled up from gram to kilogram scale, demonstrating its industrial feasibility. Mechanical and corrosion tests show that NHC-treated Cu powder thermal sprayed coatings have superior inter-particle bonding compared to those from untreated-Cu powder. This approach shows great promise for improving the quality of metal powder coatings by effectively removing surface oxides.

Numerous industries such as aerospace, automotive, and additive manufacturing use metallic powders such as copper, titanium, aluminum, etc. to produce thermal spray coatings with enhanced surface properties. The performance of sprayed coatings is compromised by uncontrolled surface oxide on metal powder surfaces which weakens inter-particle bonding. Previous methods for removing surface oxides require ultra-high vacuum conditions or lack a capping agent to prevent re-oxidation. The goal of this study is to explore an innovative one-pot immersion methodology to modify metallic surfaces with N-heterocyclic carbenes (NHCs), to remove surface oxide and cap the metal surfaces to prevent re-oxidation. The confirmation of NHC on the metal powders surface will be done using X-ray photoelectron spectroscopy, and laser desorption/ionization mass spectrometry. The optimized protocol will be scaled up from gram to kilogram scale for an extensive coating build-up process. This approach shows great promise in generating corrosion-resistant surfaces by effectively removing surface oxides and increasing inter-particle bonding.

X-ray photoelectron spectroscopy (XPS) is widely employed across various research fields due to its surface and chemical sensitivity. However, accurate interpretation poses a challenge due to the lack of comprehensive reference data in the literature, leading to misinterpretation, especially among novice users. Analyzing the chemical state of indium and indium-containing compounds is particularly challenging due to subtle shifts in the binding energies of the commonly used 3d core line. This paper presents and discusses a collection of reference data, including the In 3d, In 3p, In 4d, In MNN, and relevant counter ion signals. Additionally, it explores other useful information such as the modified Auger parameter and Wagner (or chemical state) plots. The utility of X-ray-induced Auger electrons is demonstrated in the speciation of mixed systems.

In an interview in 1982, which was 1 year after he shared the Nobel Prize, Kai Siegbahn was asked about his opinion regarding the name of the technique he had developed. Siegbahn had named it "electron spectroscopy for chemical analysis" (ESCA), but the community was choosing to call it "X-ray photoelectron spectroscopy" (XPS). Now, more than 40 years later, 20 XPS experts have given their opinions on Siegbahn's response and the name of the technique. Some of these participants have been doing XPS for many years and have provided a historical perspective on this issue. While there is no call in these comments for the community to return to "ESCA"-"XPS" is regarded as a more than an adequate name, and insisting on a name change at this point in time would probably only create confusion. However, some of the participants of this study still consider "ESCA" to be an acceptable way to refer to the technique, especially when it is used in a chemical context.

The reversible electrodeposition of iron metal in aqueous electrolytes is a promising strategy for enabling cost-effective, large-scale aqueous rechargeable batteries. However, its practical viability is hindered by parasitic side reactions, particularly the hydrogen evolution reaction (HER), which lowers coulombic efficiency, and by the instability of deposited iron, leading to corrosion, capacity loss, and reduced cycle life. This study investigates the impact of three distinct ferrous-based electrolytes-sulfate (FeSO4), chloride (FeCl2), and trifluoromethane sulfonate (Fe(OTf)2)-on the reversible deposition behavior and passivation dynamics of iron metal anodes. Surface analysis reveals that electrolyte composition critically influences passivation layer formation, directly affecting stability and efficiency. FeSO4 and Fe(OTf)2 generate compact, iron-oxide/hydroxide-rich films that suppress hydrogen evolution, resist corrosion, and deliver high coulombic efficiencies during cycling. Notably, Fe(OTf)2 is especially effective at stabilizing the electrodeposited iron metal during long-term storage, exhibiting minimal self-discharge behavior. Conversely, FeCl2 leads to inadequate passivation, resulting in lower efficiency of electrodeposition and rapid loss of plated iron due to self-discharge. While increasing current density and electrolyte concentration can reduce water activity and improve deposition efficiency through kinetic regulation, we show that a stable, hydrated solid-electrolyte interphase is crucial for long-term corrosion protection and the durability of iron anodes in aqueous batteries.

In this paper, a review of the analysis of Fe 2p3/2 peak and other transition metals in the austenitic stainless steel literature is presented. It reveals the significant shortcomings of the most widely used approaches, based on the principle of “chemistry fitting,” where single symmetric peaks are used to represent either individual oxidation states or specific compounds. No meaningful conclusions can be drawn from these commonly employed two- or three-component peak fitting (2C and 3C) approaches; the implication being that a large portion of the literature that relies on this approach is flawed. As a significantly more accurate and reliable alternative to “chemistry fitting,” we also assess “envelope fitting” (using empirical multiplet structures) and examine its limitations when applying the approach to austenitic stainless steel data. A detailed comparison of these two fitting approaches is described in Part I. For other elements such as Cr 2p, the problems associated with using single components to represent oxidation states or compounds are not as severe. It was found that it does not impact binding energy measurements, but does influence relative intensities, which will have a flow-on effect for oxide thickness calculations and obtaining a correct understanding of the surface more broadly.

The chemical nature of adventitious carbon (AdC), a thin layer of carbonaceous material that deposits on the surface of most air-exposed samples and is widely used for charge correction of insulating materials in X-ray photoelectron spectroscopy (XPS), has been investigated by XPS and time-of-flight secondary ion mass spectrometry (ToF-SIMS) on a variety of air-exposed samples from various material classes. The results from this case study show that on average AdC is aliphatic in nature with similar to 25 % of carbon species having bonds to oxygen. Dparameter and ToF-SIMS results show that AdC is not graphitic in nature, as had been suggested in earlier studies. Using assumptions about volatile organic compounds (VOC) in air that contribute to AdC accumulation, a peak-fitting model for the C 1 s XPS spectrum of AdC including beta shifted carbon peaks was developed. This model is shown to increase accuracy of the positioning of the aliphatic peak. Using this model and data from 117 samples an AdC C 1 s aliphatic peak binding energy of 284.81 eV (+/-0.25 eV) was found. Average XPS and ToFSIMS AdC spectra are presented. The average AdC XPS spectrum has been utilized to model the C 1 s spectrum of complex organic compounds with AdC present.

Although the functionalization of noble metals with N-heterocyclic carbenes (NHCs) is well-known, the interactions of these versatile ligands with common alloys are not. Herein, we present an immersion-deposition approach that enables the modification of mild steel (MiS) with diisopropylbenzimidazolium hydrogen carbonate ( iPr NHCH 2 CO 3 ). The NHC-modified surface was characterized by X-ray photoelectron spectroscopy, angle-resolved X-ray photoelectron spectroscopy, atomic force microscopy-based infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. These experimental methods provide support for the functionalization of mild steel with iPr NHC and for the reduction of surface oxide by the carbene. Electrochemical analyses and salt immersion tests were also performed and they showed that the NHC coating increases the corrosion resistance of MiS. This study demonstrates that immersion deposition is a viable method for the modification of mild steel surfaces with N-heterocyclic carbenes and shows the potential for mitigating corrosion.

Analyzing transition metal XPS peaks is widely used to determine surface composition and chemistry. However, these peaks have a complex structure, which is still the subject of investigation. Fe 2p analysis is a case in point where the multiplet structure and many-electron-effects lead to peak shapes that cannot be analyzed using standard approaches. Examination of the literature reveals that one of the most widely used approaches to data reduction when processing Fe 2p3/2 spectra involves using symmetric two- or three-component peak fitting with each peak effectively acting to capture a single chemical species (chemistry fit) in the complex spectra. Herein, this approach is compared to an envelope fit approach using Biesinger multiplet components of known iron oxides to determine how effective these methods are in reproducing iron oxide composition. Mixed oxide and metal XPS Fe 2p spectra were synthesized using reference spectra collected experimentally. For the first time, the accuracy and differences between the two approaches are reported. It is demonstrated that no meaningful conclusions can be drawn using single symmetric peaks to analyze complex Fe 2p3/2 spectra, implying that a large portion of the literature is flawed. The envelope fit approach, however, is shown to provide useful information regarding oxide ratios in mixed iron oxide materials, though limitations do exist. A methodology for evaluating the quality of XPS analysis of Fe 2p3/2 spectra is proposed for benchmarking new submissions so that reviewers, authors, and editors can assess these submissions.

This study considers how poor x-ray photoelectron spectroscopy (XPS) peak fitting in the scientific literature is both affected by previous precedent and affects future published work. It focuses on a highly cited paper (the "Subject" paper) from a respected journal that contains incorrect S 2p peak fits. This paper was studied in a genealogical fashion vis-a-vis the XPS peak fitting in its "child," "parent," "grandparent," and "great-grandparent" papers. Interestingly, precedents were not followed to a high degree between parent and child papers. However, in many cases, even when the authors of a study did not follow the incorrect precedent that they cited, they still incorrectly fit their data. Thus, not necessarily for good reasons, the effects of poor XPS peak fits on future generations of papers may be less than some experts had expected or feared. In many cases, older papers appear to contain better XPS peak fitting than newer ones.

Abstract The pitting corrosion, passive film morphology, and surface composition of copper were studied in chloride-containing bicarbonate buffer solutions using multielectrode arrays and single electrodes. Cu was shown to be susceptible to pitting in 0.01 and 0.1 M Cl¯, but to experience active dissolution in 1 M Cl¯. The passive film morphology and composition were investigated using the single-electrode setup. Surface analyses showed the presence of pits in both 0.01 and 0.1 M Cl¯ buffer solutions. The results indicated the dependency of passive film morphology and composition on both charge density and applied potential.

The used fuel container (UFC) is a key engineered barrier to permanently contain and isolate used nuclear fuels underground in deep geological repositories (DGR) to be implemented in Canada, Sweden and Finland.1,2 Copper is used for corrosion protection in the current design of the UFC. Within a DGR, radiolysis of humid air will result in the formation of nitric acid.3 Recent studies showed that copper corrodes faster in nitric acid when oxygen is present, which will be the case for a short period after the UFC’s emplacement.4 When the oxygen becomes depleted in a DGR, the corrosion of copper will be minimal but can be affected by corrosion products such as Cu+, Cu2+, NO2 - and NO. Previous results suggest that the presence of copper ions in the solution surrounding the copper can activate nitrate as a cathodic reagent.5 A possible mechanism is that Cu+ reacts with nitrate through its oxidation to Cu2+, which then reacts with metallic copper through its comproportionation reaction, accelerating the corrosion process.5 Yet, a precise mechanistic understanding of the role of Cu+, such as the degree to which oxidation of Cu+ occurs in solution, or if Cu+ simply acts as a catalyst for nitrate reduction or decomposition, is missing. As a result, an improved understanding of the influence of solution parameters on the corrosion mechanisms of copper in nitric acid is needed, including the presence of oxidants and Cu+-chelating species such as chloride. Herein, the interplay between the dissolved redox couples, Cu+/Cu2+ and NO3 -/NO2 - and Cl- is explored, and their effect on the corrosion of copper is studied by linear sweep voltammetry and polarization resistance and Tafel analysis. The interpretation of linear polarization resistance measurements in the presence of multivalent ions and the role of corrosion products are discussed. 1 P. G. Keech, P. Vo, S. Ramamurthy, J. Chen, R. Jacklin and D. W. Shoesmith, Corrosion Engineering, Science and Technology, 49, 2014, 425-430. 2 F. King, L. Ahonen, C. Taxen, U. Vuorinen and L. Werme, Copper corrosion under expected conditions in a deep geologic repository (SKB-TR--01-23), 2001. Sweden. 3 R. P. Morco, J. M. Joseph, D. S. Hall, C. Medri, D. W. Shoesmith and J. C. Wren, Corrosion Engineering, Science and Technology, 52, 2017, 141-147. 4 J. Turnbull, R. Szukalo, M. Behazin, D. Hall, D. Zagidulin, S. Ramamurthy, J. Wren and D. Shoesmith, Corrosion, 74, 2017, 326-336. 5 J. Turnbull, R. Szukalo, D. Zagidulin, M. Biesinger and D. W. Shoesmith, Materials and Corrosion, 72, 2021, 348–360.

Copper (Cu) and stainless steel 316 L are widely used for biomedical applications, such as intrauterine devices and orthopedic/dental implants. Amino acids are abundantly present in biological environments. We investigated the influence of select amino acids on the corrosion of Cu under naturally aerated and deaerated conditions using a phosphate-free buffer. Amino acids increased the corrosion of Cu under both aeration conditions at pH 7.4. Cu release was also significantly (up to 18-fold) increased in the presence of amino acids, investigated at pH 7.4 and 37 °C for 24 h under naturally aerated conditions. Speciation modelling predicted a generally increased solubility of Cu in the presence of amino acids at pH 7.4. 316 L, investigated for metal release under similar conditions for comparison, released about 1,000-fold lower amounts of metals than did Cu and remained passive with no change in surface oxide composition or thickness. However, amino acids also increased the chromium release (up to 52-fold), significantly for lysine, and the iron release for cysteine, while nickel and molybdenum release remained unaffected. This was not predicted by solution speciation modelling. The surface analysis confirmed the adsorption of amino acids on 316 L and, to a lower extent, Cu coupons.