Effect of doping ofnanoporous adsorbent with nanodispersed metals or semi-metals on their hydrogen strorage properties ; Effets du dopage d'adsorbants nanoporeux par des métaux ou des semi-métaux nanodispersés sur leurs performances en stockage d'hydrogène par sorption

In this PhD work, microporous carbonaceous materials decorated with metallic nanoparticles were developed in order to study the effect of nanodispersed metals on hydrogen sorption properties. Bio-sourced precursors such as sucrose, mimosa tannins or even rice straw have been used in order to promote eco-friendly, sustainable and innovating ways of synthesis. The use of hydrothermal pretreatment on tannins or sucrose allowed obtaining hydrochars that have been chemically or physically activated. Depending on synthesis parameters, these syntheses allowed to produce materials with controlled porosity. Then, the hydrogen adsorption properties of these materials were evaluated at ambient temperature as well as their textural properties. The main interest of this work was to propose a coupling between hydrogen sorption properties, from low to high pressure, and the textural properties. The textural properties were modelized using theoretical tools such as the DFT (Density Functionnal Theory). The use the different precursors and of decoration steps using supercritical carbon dioxide or hydrothermal synthesis, during which ones metallic or nitrogen containing precursors were used, allowed to obtain nickel, nitrogen or silicon doped materials without using harmful organic solvents. Finally, the decorrelation of the different adsorption contributions gave the possibility to detect and quantify the hydrogen fractions engaged in different processes such as physisorption, chemisorption and spillover. Polarized or enhanced physisorption was also detected using the same methods ; Dans cette thèse, des matériaux microporeux carbonés et décorés par des nanoparticules métalliques ont été synthétisés afin d’étudier l’effet de la décoration par les nanoparticules métalliques sur leurs propriétés d’adsorption d’hydrogène. L’utilisation de saccharose, de tannins de mimosa ou encore de paille de riz était en parfaite cohérence avec une démarche de respect de l’environnement et de développement durable. Le saccharose ainsi que les ...