The development of earth-abundant, non-precious catalysts is essential to the deployment of proton exchange membrane fuel cells and electrolyzers, which are essential components for decarbonizing the production and utilization of chemicals and fuels, including hydrogen and ammonia. Among the electrocatalysts for such applications, transition metal nitrides have emerged as promising and cost-effective materials. However, metal nitrides are affected by dissolution in acid resulting in material degradation, hindering their use in applications. In this study, by combining experimental characterizations and DFT calculations we elucidate the fundamental properties of transition metal nitrides governing their stability in acid and provide a key mechanistic understanding for metal nitrides dissolution and resulting ammonia formation. More importantly, these results provide guiding principles for designing and optimizing novel nitride chemistries for clean energy applications.

Jiayu Peng, Juan J. Giner-Sanz, Livia Giordano, William P. Mounfield III, Graham M. Leverick, Yang Yu, Yuriy Román-Leshkov, Yang Shao-Horn, Design principles for transition metal nitride stability and ammonia generation in acid, JOULE 7, 150-157 (2023).

Natural and anthropogenic gas radionuclides such as radon, xenon, hydrogen and krypton isotopes must
be monitored to be managed as pathogenic agents, radioactive diagnostic agents or nuclear activity indicators. State-of-the-art detectors based on liquid scintillators suffer from laborious preparation and
limited solubility for gases, which affect the accuracy of the measurements. The actual challenge is to find
solid scintillating materials simultaneously capable of concentrating radioactive gases and efficiently producing visible light revealed with high sensitivity. The high porosity, combined with the use of scintillating
building blocks in metal–organic frameworks (MOFs), offers the possibility to satisfy these requisites. We
demonstrate the capability of a hafnium-based MOF incorporating dicarboxy-9,10-diphenylanthracene as a scintillating conjugated ligand to detect gas radionuclides. Metal–organic frameworks show fast scintillation, a fluorescence yield of ∼40%, and accessible porosity suitable for hosting noble gas atoms and ions. Adsorption and detection of ⁸⁵Kr, ²²²Rn and ³H radionuclides are explored through a newly developed device that is based on a time coincidence technique. Metal–organic framework crystalline powder demonstrated an improved sensitivity, showing a linear response down to a radioactivity value below 1 kBq m⁻³ for ⁸⁵Kr, which outperforms commercial devices. These results support the possible use of scintillating porous MOFs to fabricate sensitive detectors of natural and anthropogenic radionuclides.

Matteo Orfano, Jacopo Perego, Francesca Cova, Charl X. Bezuidenhout, Sergio Piva, Christophe Dujardin, Benoit Sabot, Sylvie Pierre, Pavlo Mai, Christophe Daniel, Silvia Bracco, Anna Vedda, Angiolina Comotti, Angelo Monguzzi, Efficient radioactive gas detection by scintillating porous metal–organic frameworks, NATURE PHOTONICS 17, 672–678 (2023). 

In the last 20 years, direct alcohol fuel cells (DAFCs) have been the subject of tremendous research efforts
for the potential application as on-demand power sources. Two leading technologies respectively based
on proton exchange membranes (PEMs) and anion exchange membranes (AEMs) have emerged: the first
one operating in an acidic environment and conducting protons; the second one operating in alkaline electrolytes and conducting hydroxyl ions. In this review, we present an analysis of the state-of-the-art acidic and
alkaline DAFCs fed with methanol and ethanol with the purpose to support a comparative analysis of acidic
and alkaline systems, which is missing in the current literature. A special focus is placed on the effect of the
reaction stoichiometry in acidic and alkaline systems. Particularly, we point out that, in alkaline systems,
OH− participates stoichiometrically to reactions, and that alcohol oxidation products are anions. This aspect
must be considered when designing the fuel and when making an energy evaluation from a whole system
perspective.

Enrico Berretti, Luigi Osmieri, Vincenzo Baglio, Hamish A. Miller, Jonathan Filippi, Francesco Vizza, Monica Santamaria, Stefania Specchia, Carlo Santoro, Alessandro Lavacchi, Direct alcohol fuel cells: a comparative review of acidic and alkaline systems, ELECTROCHEM. ENERGY REV. 6, 30 (2023).

Due to their superior mechanical properties, 2D materials have gained interest as active layers in flexible devices co-integrating electronic, photonic, and straintronic functions altogether. To this end, 2D bendable membranes compatible with the technological process standards and endowed with large-scale uniformity are highly desired. Here, it is reported on the realization of bendable membranes based on silicene layers (the 2D form of silicon) by means of a process in which the layers are fully detached from the native substrate and transferred onto arbitrary flexible substrates. The application of macroscopic mechanical deformations induces a strain-responsive behavior in the Raman spectrum of silicene. It is also shown that the membranes under elastic tension relaxation are prone to form microscale wrinkles displaying a local generation of strain in the silicene layer consistent with that observed under macroscopic mechanical deformation. Optothermal Raman spectroscopy measurements reveal a curvature-dependent heat dispersion in silicene wrinkles. Finally, as compelling evidence of the technological potential of the silicene membranes, it is demonstrated that they can be readily introduced into a lithographic process flow resulting in the definition of flexible device-ready architectures, a piezoresistor, and thus paving the way to a viable advance in a fully silicon-compatible technology framework.

Christian Martella, Chiara Massetti, Daya Sagar Dhungana, Emiliano Bonera, Carlo Grazianetti, Alessandro Molle, Bendable silicene membranes, ADVANCED MATERIALS 35, 2211419 (2023).

Electronic structure calculations represent an essential complement of experiments to characterize single-atom catalysts (SACs), consisting of isolated metal atoms stabilized on a support, but also to predict new catalysts. However, simulating SACs with quantum chemistry approaches is not as simple as often assumed. In this work, the essential factors that characterize a reliable simulation of SACs activity are examined. The Perspective focuses on the importance of precise atomistic characterization of the active site, since even small changes in the metal atom's surroundings can result in large changes in reactivity. The dynamical behavior and stability of SACs under working conditions, as well as the importance of adopting appropriate methods to solve the Schrödinger equation for a quantitative evaluation of reaction energies are addressed.

The Perspective also focuses on the relevance of the model adopted. For electrocatalysis this must include the effects of the solvent, the presence of electrolytes, the pH, and the external potential. Finally, it is discussed how the similarities between SACs and coordination compounds may result in reaction intermediates that usually are not observed on metal electrodes. When these aspects are not adequately considered, the predictive power of electronic structure calculations is quite limited.

Giovanni Di Liberto, Gianfranco Pacchioni, Modeling single-atom catalysis, ADVANCED MATERIALS 35, 2307150 (2023).