Marco Faustini

Jeudi 10 avril à 13h30 - From Nanostructured Oxides to Porous High Entropy Alloys: Bridging Sol-Gel Processing and Metallurgy

Marco FAUSTINI

Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP)

Résumé :

The sol-gel process is traditionally used to shape oxides; it offers a versatile and well-established route to synthesize nanostructured materials from solutions with controlled composition, porosity, and morphology. Our research aims to push the boundaries of sol-gel processing beyond oxides, extending its applicability to the shaping of metallic materials, which presents additional challenges related to reduction processes, phase control, and structural integrity. To introduce this chemistry, we will start by discussing the case of noble metal oxides, particularly porous Ir-based and mixed oxides, which are key materials for the oxygen evolution reaction in proton exchange membrane water electrolyzers. In particular, we unveil that the spontaneous formation of hollow structures can be achieved thanks to the pseudo-Kirkendall process on metallic salts. Building on this foundation, we then tackle the more complex and challenging case of metallic high entropy alloys (HEAs), a class of materials composed of five or more homogeneously mixed elements in nearly equimolar ratios. HEAs have rapidly gained importance in the field of catalysis and electrocatalysis, due to their high chemical and thermal stability and to the virtually unlimited types of active sites accessible, stemming from the high configurational entropy. [1] However, fabrication of these materials usually requires harsh conditions. By using the brute force of spray-drying, we developed a low temperature sol-gel approach to shape HEA nanoparticles into macro- and mesoporous architectures. [2] Porous, fully reduced HEA-based particles are obtained by annealing the hybrid particles at temperatures as low as 350°C under inert atmosphere by carbothermal treatment showed a good catalytic activity towards the CO oxidation reaction and stability up to 800°C. A multi-technique in situ analysis was performed to understand the solid-state carboreduction process at the hybrid organic/inorganic interface and the atomic mixing. Moreover, we extended the sol-gel approach to shape metallic material as films and patterns by combining this chemistry with Nanoimprint Lithography or Deep X-Ray Lithography [3,4]. In conclusion, this work shows a versatile approach for the exploration of architectured metallic materials with important implications in optics, catalysis and electrocatalysis.

[1] Y. Xin, S. Li, Y. Qian, W. Zhu, H. Yuan, P. Jiang, R. Guo, L. Wang, ACS Catal. 10, 11280−11306 (2020).

[2] M. L. De Marco, W. Baaziz, S. Sharna, F. Devred, C. Poleunis, A. Chevillot-Biraud, S. Nowak, R. Haddad, M. Odziomek, C. Boissiere, ̀D. P. Debecker, O. Ersen, J. Peron, M. Faustini, ACS Nano, 16, 15837-15849 (2022)

[3] M. Gayrard; J. Voronkoff; C. Boissière; D. Montero; L. Rozes; A. Cattoni; J. Peron; M. Faustini , Nano Letters, 21, 5, 2310-2317, (2021)

[4] M. Gayrard; F. Chancerel; M. L. De Marco, D. Naumenko, C. Boissière; L. Rozes; H. Amenitsch; J. Peron; A. Cattoni; M. Faustini, Small, 18, 2104204, (2022)

Lien zoom : https://univ-nantes-fr.zoom.us/s/87866932617
ID de réunion : 878 6693 2617
Code secret : 872176

Contact : Stéphane Jobic (MIOPS)