Cold-gas spray (CGS) deposition of amorphous steel coatings starting from a commercial feedstock powder containing boron, tungsten, and silicon was investigated. Microstructural characterization, carried out by X-ray diffraction (XRD), transmission electron microscopy, and backscattered electron diffraction (EBSD) analysis, confirmed the amorphous nature of deposited coatings. The amorphization phenomenon is related to high-strain/strain-rate deformation with shear instability caused by very high particle kinetic energy, with a mechanism that resembles the severe plastic deformation process. The CGS coatings were heat-treated at temperatures ranging from 650 to 850 °C to induce partial recrystallization. The effect of nanocrystal nucleation and growth on the hardness of the coatings was investigated, and the hardness of heat-treated samples was found to increase with respect to as-sprayed coatings, outperforming conventional high-velocity oxy-fuel (HVOF) deposits. Hardness was found to decrease after prolonged (750 °C) exposures.

Per- and polyfluoroalkyl substances (PFAS) have found wide application in proton exchange membrane fuel cells (PEMFCs) and water electrolysers (PEMELs), thanks to their exceptional chemical and thermal stability. However, their environmental persistence and growing regulatory pressure—particularly from the European Union—have made the transition to PFAS-free components a priority. This work reviews current advancements in alternative materials that can guarantee the same performance or maybe improve it. Although several non-fluorinated materials have demonstrated initial performance close to PFAS-based benchmarks, significant challenges remain. These include limited long-term stability, difficulties for new materials to fit into existing stack architectures, and the lack of standardized testing protocols. Nevertheless, recent efforts have successfully demonstrated a PFAS-free PEM electrolyser stack at TRL 4, validating the technical feasibility of full PFAS substitution. Achieving commercial readiness will require parallel progress in materials development and industrial scalability. This review highlights the possibility that hydrogen technologies, such as fuel cells and electrolysers, which are called upon to support the energy transition towards a more sustainable future, are themselves truly environmentally friendly, thus making their use as green as possible.

Among the challenges posed by the COVID-19 pandemic, significant efforts have been undertaken to develop antimicrobial/antiviral surfaces by exploiting coating solutions. In this article, we review the actions undertaken by the EU project MIRIA, the main one being the reduction of pathogen transmission on high-traffic surfaces in public and healthcare environments. The project implements several synergies from key antimicrobial/antiviral element selection to the grafting of complex-shaped surfaces. The focus is given to one of the project’s key strategies: the adoption of sol-gel technology, known for its efficiency in creating versatile, cost-effective coatings suitable for a wide range of substrates. The project rigorously tests the coatings in simulated environments, such as operating theatres, ensuring their effectiveness and safety. This includes comprehensive durability testing against environmental, chemical, and mechanical stresses, guaranteeing the coatings’ long-term functionality. MIRIA’s validation process encompasses antibacterial, antifungal, and antiviral testing in line with international standards, confirming their broad-spectrum pathogen resistance. Along with this overview, the impact of the initiative is elucidated, extending beyond healthcare, enhancing public health, creating safer living, and working environments, and reducing economic losses due to illness. To this, the MIRIA project is expected to significantly contribute to the European research and innovation in antimicrobial coatings, addressing challenges like scalability and efficacy against various pathogens. The emphasis on sustainable synthesis, including bio-based materials which align with ecological goals, positions MIRIA as a pivotal initiative in enhancing health safety standards and resilience across Europe. Graphical Abstract