We evidence the structure-directing role of the PW12O403− polyoxometalate in porphyrinic MOF synthesis whereby it promotes the formation of the kinetic topology. Its immobilization into the MOF is successfully achieved at a high temperature yielding the kinetic MOF-525/PCN-224 phases, while prohibiting the formation of the thermodynamic MOF-545 product. A combined experimental/theoretical approach uses differential PDF and DFT calculations along with solid-state NMR to show the structural integrity of the POM and its location next to the Zr-based nodes.
Monitoring the dynamic chemical and thermal state of a cell during operation is crucial to making meaningful advancements in battery technology as safety and reliability cannot be compromised. Here we demonstrate the feasibility of incorporating optical fibre Bragg grating sensors into commercial 18650 cells. By adjusting fibre morphologies, wavelength changes associated with both temperature and pressure are decoupled with high accuracy, which allows tracking of chemical events such as solid electrolyte interphase formation and structural evolution. We also demonstrate how multiple sensors are used to determine the heat generated by the cell without resorting to microcalorimetry. Unlike with conventional isothermal calorimetry, the cell’s heat capacity contribution is readily assessed, allowing for full parametrization of the thermal model. Collectively, these findings offer a scalable solution for screening electrolyte additives, rapidly identifying the best formation processes of commercial cells and designing battery thermal management systems with enhanced safety.
Operando decoding of chemical and thermal events in commercial Na(Li)-ion cells via optical sensors, Nature Energy volume 5, pages 674–683 (2020)
This paper studies the evolution of the pore size distribution of a fresh unconsolidated geopolymer paste between one day and a week, using thermoporometry. This was made possible by following a careful protocol for sample preparation and for analysis by differential scanning calorimetry. In contrast with nitrogen gas adsorption, this method quantifies directly the amount of water in pores. It also does not require heat and vacuum drying, thus maintaining the fragile pore structure of the unconsolidated paste. Moreover, it was found that, in a typical metakaolin‐based sodium geopolymer with a 10 to 20 hours workability period, the porosity gradually refines during the first week while the mesoporous volume is cut in half. This is probably due to the fact that the geopolymer network was still actively condensing from the activation solution. Part of the pore water never froze and, from mass balance, this residual water was attributed to the water bound in the hydration shell of the sodium counter ions. Only a minor occurrence of covalently bound protons as silanol groups was observed. The results presented here usefully complement data obtained by conventional techniques at later ages on consolidated geopolymers. It supports the growing body of literature on the structural evolution of geopolymers with time.
Evolution of the microstructure of unconsolidated geopolymers by thermoporometry, Journal of the American Ceramic Society, 2020.
Isophthalic acid (IPA) has been considered to build metal-organic frameworks (MOFs), owing to its facile availability, unique connection angle-mode, and a wide range of functional groups attached. Constructing titanium-IPA frameworks that possess photoresponse properties is an alluring characteristic with respect to the challenge of synthesizing new titanium-based MOFs (Ti-MOFs). Here, we report the first Ti-IPA MOF (MIP-208) that efficiently combines the use of preformed Ti8 oxoclusters and in situ acetylation of the 5-NH2-IPA linker. The mixed solid-solution linkers strategy was successfully applied, resulting in a series of multivariate MIP-208 structures with tunable chemical environments and sizable porosity. MIP-208 shows the best result among the pureMOF catalysts for the photocatalytic methanation of carbon dioxide. To improve the photocatalytic performance, ruthenium oxide nanoparticles were photo-deposited on MIP-208, forming a highly active and selective composite catalyst, MIP-208@RuOx, which features a notable visible-light.
In this paper, we study the drying of water-saturated porous polydimethylsiloxane (PDMS) elastomers with closed porosity in which the evaporation of water is possible only via the diffusion across PDMS. Starting from water/PDMS emulsions, we fabricate soft macroporous samples with different pore diameter distributions and average diameters ranging from 10 to 300 mm. In these materials, the drying may lead to either a collapsed state with low porosity or the cavitation and reopening of a fraction of the pores. Using optical microscopy and porosity measurements, we showed the influence of the pore diameters and interactions on the result of drying.
Collapse and cavitation during the drying of water-saturated PDMS sponges with closed porosity, Royal Society of Chemistry, 2020.
Mesoporous silica nanoparticles (MSNs) have seen a fast development as drug delivery carriers thanks to their tunable porosity and high loading capacity. The employ of MSNs in biomedical applications requires a good understanding of their degradation behavior both to control drug release and to assess possible toxicity issues on human health. In this work, we study mesoporous silica degradation in biologically relevant conditions through in situ ellipsometry on model mesoporous nanoparticle or continuous thin films, in buffer solution and in media containing proteins.
Following in Situ the Degradation of Mesoporous Silica in Biorelevant Conditions: At Last, a Good Comprehension of the Structure Influence, Journal of the American Chemical Society 2020