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MXenes have gained significant attention, particularly Ti3C2Tz, as materials with favorable properties for energy storage and conversion applications. The overwhelming majority of electrochemical durability studies are based on durability in the hydrogen evolution window, well below the reversible hydrogen electrode where degradation via electrochemical oxidation is less relevant. Consequently, few strategies have been put forward to protect Ti3C2Tz at higher potentials and widen their applicability to electrochemical systems. Here, the electrochemical degradation of pristine Ti3C2Tz and tantalum (Ta)‐substituted (Ti0.95Ta0.05)3C2Tz is reported. X‐ray photoelectron spectroscopy and electron microscopy revealed that pristine and Ta‐doped MXene went through entirely different degradation mechanisms, and that these mechanisms are driven by electrochemical, rather than chemical effects. Density functional theory is used to explain the role of Ta doping with respect to the binding of oxygen and the formation of metal oxide phases. The influence of the degradation mechanism is observed by accelerated stress tests and anode reversal tests on a polymer electrolyte membrane fuel cell. Therefore, the substitution of titanium (Ti) with other oxyphilic metals in Ti3C2Tz may be an effective route to improve the durability of the otherwise fragile MXene phase. [ABSTRACT FROM AUTHOR]

As hydrogen is touted as a key player in the decarbonization of modern society, it is critical to enable quantitative hydrogen (H) analysis at high spatial resolution and, if possible, at the atomic scale. H has a known deleterious impact on the mechanical properties (strength, ductility, toughness) of most materials that can hinder their use as part of the infrastructure of a hydrogen-based economy. Enabling H mapping including local hydrogen concentration analyses at specific microstructural features is essential for understanding the multiple ways that H affect the properties of materials including embrittlement mechanisms and their synergies. In addition, spatial mapping and quantification of hydrogen isotopes is essential to accurately predict tritium inventory of future fusion power plants thus ensuring their safe and efficient operation. Atom probe tomography (APT) has the intrinsic capability to detect H and deuterium (D), and in principle the capacity for performing quantitative mapping of H within a material's microstructure. Yet, the accuracy and precision of H analysis by APT remain affected by complex field evaporation behavior and the influence of residual hydrogen from the ultrahigh vacuum chamber that can obscure the signal of H from within the material. The present article reports a summary of discussions at a focused workshop held at the Max-Planck Institute for Sustainable Materials in April 2024. The workshop was organized to pave the way to establishing best practices in reporting APT data for the analysis of H. We first summarize the key aspects of the intricacies of H analysis by APT and then propose a path for better reporting of the relevant data to support interpretation of APT-based H analysis in materials., Competing Interests: Conflict of Interest The authors declare that they have no competing interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Microscopy Society of America.)

2D materials are emerging as promising nanomaterials for applications in energy storage and catalysis. In the wet chemical synthesis of MXenes, these 2D transition metal carbides and nitrides are terminated with a variety of functional groups, and cations such as Li+ are often used to intercalate into the structure to obtain exfoliated nanosheets. Given the various elements involved in their synthesis, it is crucial to determine the detailed chemical composition of the final product, in order to better assess and understand the relationships between composition and properties of these materials. To facilitate atom probe tomography analysis of these materials, a revised specimen preparation method is presented in this study. A colloidal Ti3C2Tz MXene solution was processed into an additive-free free-standing film and specimens were prepared using a dual beam scanning electron microscope/focused ion beam. To mechanically stabilize the fragile specimens, they were coated using an in situ sputtering technique. As various 2D material inks can be processed into such free-standing films, the presented approach is pivotal for enabling atom probe analysis of other 2D materials., Competing Interests: Conflict of Interest. The authors declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Microscopy Society of America.)

MXenes are a family of 2D transition metal carbides and nitrides with remarkable properties, bearing great potential for energy storage and catalysis applications. However, their oxidation behavior is not yet fully understood, and there are still open questions regarding the spatial distribution and precise quantification of surface terminations, intercalated ions, and possible uncontrolled impurities incorporated during synthesis and processing. Here, atom probe tomography (APT) analysis of as-synthesized Ti 3 C 2 T x MXenes reveals the presence of alkali (Li, Na) and halogen (Cl, F) elements as well as unetched Al. Following oxidation of the colloidal solution of MXenes, it is observed that the alkalis are enriched in TiO 2 nanowires. Although these elements are tolerated through the incorporation by wet chemical synthesis, they are often overlooked when the activity of these materials is considered, particularly during catalytic testing. This work demonstrates how the capability of APT to image these elements in 3D at the near-atomic scale can help to better understand the activity and degradation of MXenes, in order to guide their synthesis for superior functional properties., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Objectives: To formally establish the relationship between oxycodone dissolution, in vitro, from a prolonged-release, oral, combination of oxycodone and naloxone (OXN PR) tablets with in vivo absorption, by developing a validated Level A in vitro/in vivo correlation (IVIVC) and subsequently ascertaining the temporal absorption of oxycodone during gastrointestinal transit., Methods: In vitro dissolution data from formulations of OXN PR (20/10 mg) tablets with slow, medium and fast dissolution rates were generated using United States Pharmacopeia I apparatus 2 (paddle at 50 rpm) in simulated gastric fluid, pH 1.2. These batches were administered to healthy volunteers and plasma concentration data were collected during a randomised, open-label, cross-over study. A Level A correlation was established for oxycodone through the determination of in vivo absorption profiles obtained by deconvolution of plasma concentrations with in vitro dissolution data. The IVIVC model was validated using the internal predictability assessment., Results: A Level A correlation between the in vitro and in vivo release data was established. The polynomial function describing the IVIVC produced a goodness of fit (R(2)) of 0.99., Conclusions: The rate of absorption of oxycodone from OXN PR tablets correlated well with the in vitro release rates, demonstrating that a Level A IVIVC with internal predictability has been successfully developed for OXN PR tablets. In conjunction with a previous gastrointestinal transit study, this report demonstrates that the majority of oxycodone enters the circulation before reaching the colon, thus it is important that naloxone counteracts opioid-induced bowel dysfunction throughout the entire gut.