Andrea Frazzica

Atmospheric water harvesting (AWH) has emerged as a promising strategy for decentralised freshwater production in regions where conventional water infrastructure is limited. Among the various approaches, sorption-based systems employing metal–organic frameworks (MOFs) are particularly attractive due to their high surface area and tunable pore chemistry. In this work, we report the development of structured photothermal composite beads based on Ca²⁺-crosslinked sodium alginate (SA) incorporating MIL-101(Cr) and MIL-100(Fe) MOFs together with graphene oxide (GO) as a solar absorber. The resulting MOF–alginate–GO beads combine high water adsorption capacity with efficient photothermal regeneration and good mechanical robustness. The Ca²⁺-crosslinked alginate network acts as a water-permeable hydrogel scaffold, enabling repeated swelling–drying cycles while integrating MOF sorption capacity and GO-mediated light-to-heat conversion. Dynamic vapour sorption measurements reveal characteristic cooperative adsorption behaviour, with MIL-101(Cr) beads exhibiting an earlier adsorption step at ~30–40% RH, while MIL-100(Fe) beads activate at ~45–55% RH. Under simulated solar irradiation (1 sun), the incorporation of GO enhances solar-to-thermal conversion, increasing the fraction of desorbed water by approximately 22%, 12%, and 8% relative to the corresponding GO-free SA, Fe/SA, and Cr/SA formulations, respectively. These results highlight the potential of MOF–alginate photothermal composites as scalable sorbents for solar-driven atmospheric water harvesting, particularly in moderate-humidity environments.

This study explores novel silica gel/sulfonated polymer composite coatings for enhanced thermal management in electric vehicles via sorption technology. Leveraging the cost-effectiveness of silica gel as a filler and a readily available, water vapor-permeable sulfonated polymer as the matrix, we developed and characterized these materials. Mechanical assessments revealed varied performance: coatings with lower silica gel content (80 and 85 wt%) demonstrated suitable scratch resistance (damage width ~1100 µm at 1300 g load) and superior impact resistance (damage diameter ~2.4 mm). Pull-off adhesion strengths for these batches were 1.26 MPa and 1.36 MPa, respectively, though higher filler loading (90 and 95 wt%) led to a ~30% reduction and a shift to cohesive failure for high-filler-content batches. Thermogravimetric analysis confirmed thermal stability up to 280 °C. Adsorption studies revealed that the composite coating with 95 wt% of silica gel achieved the highest water uptake (just under 30 wt%), with all batches exhibiting capacities comparable to commercial adsorbents. This comprehensive characterization confirms that these composites offer a compelling balance of mechanical robustness, reliable adhesion, and high adsorption efficiency, positioning them as promising, cost-effective solutions for EV thermal management.

Combining different materials into binary salts can significantly enhance the efficiency and stability of Thermochemical Energy Storage (TCES) systems. This study aimed to develop and characterise novel salt hydrate composite materials for TCES, focusing on a mixture of magnesium chloride (MgCl₂) and calcium chloride (CaCl₂) impregnated into a mesoporous silica gel (SG) sphere matrix. Three different MgCl₂/CaCl₂ salt ratios were investigated to find the optimal balance between sorption capacity and stability against deliquescence in humid environments. Prepared samples underwent comprehensive characterisation, including structural and morphological analysis, water vapour sorption and heat capacity measurements. The hybrid CaCl15/MgCl15/SG sample exhibited intermediate behavior between the pure CaCl30/SG and MgCl30/SG samples, with significantly improved stability in a humid environment due to the addition MgCl₂. Characterisation revealed the effective confinement of the salt mix in the matrix. The optimised CaCl15/MgCl15/SG sample demonstrated highly promising gravimetric and volumetric energy storage capacities of 1092 J/g and 2.3 MJ/m³, respectively, comparable to recently reported composites. The material sorption dynamics were ultimately tested in a whole adsorbent unit under near-real-world operating conditions, pushing the research to the reactor and system level, and demonstrating that the presence of MgCl₂ in the composite does not adversely affect the adsorption kinetics compared to the pure CaCl₂-based composite.

The continuous increasing of renewable-based energy systems, both for heating and power generation, at building level requires the development of innovative compact hybrid energy storages. These technologies are able to support the flexible operation of such complex systems, increasing the exploitability of renewables and the overall system efficiency. In this chapter, a brief overview of different storage technologies, such as thermal, electric and hybrid, at building level is provided, mostly focusing on their integration with onsite renewable generation and smart grids. The analysis highlights the relevant role of flexible energy storages at building level as well as the lack of innovative components able to provide multiple services (e.g. heating, cooling, domestic hot water and power) to buildings. In such a background, the experience carried out in the framework of the EU-funded HYBUILD project is described. The overall concept, integrating electric batteries, latent, and thermochemical storages, with highly efficient reversible heat pumps is described, showing the different options developed for continental and mediterranean climates. The fully integrated Mediterranean system, validated both at lab-scale and in a demo building, demonstrated the ability of increasing the share of renewables in buildings, maximizing the self-consumption and increasing the overall energy efficiency of the system.

The global scarcity of freshwater, driven by population growth and the unequal distribution of water resources, has intensified the need for alternative water supply technologies. Among the most promising solutions, adsorption-based atmospheric water harvesting (AWH) systems offer the ability to extract water vapor directly from ambient air, even under low-humidity conditions. This review presents a comprehensive overview of the thermodynamic principles and material characteristics governing these systems, with particular emphasis on adsorption isotherms and their role in predicting and optimizing system performance. A generalized theoretical framework is proposed to assess the energy efficiency of thermally driven AWH devices, based on key material parameters. Recent developments in sorbent materials, especially metal–organic frameworks (MOFs) and advanced zeolites, are examined for their high-water uptake, regeneration efficiency, and potential for operation under real climatic conditions. The Dubinin–Astakhov and modified Langmuir isotherm models are reviewed for their effectiveness in describing nonlinear sorption behaviors critical to performance modeling. In addition, component-level design strategies for adsorption-based AWH systems are discussed. The integration of solar energy is also discussed, highlighting recent prototypes and design strategies that have achieved water yields ranging from 0.1 to 2.5 L m⁻²/day and specific productivities up to 2.8 L kg⁻¹ using MOF-801 at 20% RH. Despite notable progress, challenges remain, including limited productivity in non-optimized setups, thermal losses, long-term material stability, and scalability. This review concludes by identifying future directions for material development, system integration, and modeling approaches to advance the practical deployment of efficient and scalable AWH technologies.