TEMPLATED SYNTHESIS OF POROUS HEA-BASED MATERIALS

De Marco, Maria Letizia Baaziz, Walid Sharna, Sahrmin Devred, François [UCL] Poleunis, Claude [UCL] Chevillot-Biraud, Alexandre Nowak, Sophie Haddad, Ryma Odziomek, Mateusz Boissière, Cédric Debecker, Damien P. [UCL] Ersen, Ovidiu Peron, Jennifer Faustini, Marco et al.[show all]

A templated aerosol approach, inspired to the sol-gel synthesis of porous oxides has been applied for the fabrication of HEA-based porous materials. The process consists on spray-drying an aqueous suspension containing the metal salts (PtCl4, PdCl2, IrCl3, RhCl3 and RuCl3) in nearly equimolar concentrations, mixed with polymer latex particles, using a B-290 mini spray-dryer whose nozzle is heated at 150⁰C. This generates an aerosol of droplets containing the dissolved metal salts and latex particles. Water evaporation induces latex particles self-assembly (EISA), yielding spherical super-structures of latex particles embedded in a matrix of metal salt (see figure 1). In this first step, homogeneous and random precursors mixing, required for the formation of a HEA, is achieved. Thermal annealing under inert atmosphere produces porous particles with a single fcc crystalline structure. The advantage of this approach is that the size of the pores can be tuned by choosing the size of the latex template particles. In this work, we produced both mesoporous particles and hierarchical macro- and mesoporous particles, with specific surface area of 150 m2/g and 103 m2/g respectively. These values are the highest obtained so far in the field of HEAs. STEM-EDX revealed that these porous structures are actually built of tiny nanocrystals (about 4-5 nm) with a fcc crystalline structure. Time of flight secondary ion mass spectroscopy confirmed the intimate and random alloying of the five elements at the atomic scale within the nanocrystals.