Self-catalyzed hydrogenation and dihydrogen adsorption on titanium carbide nanoparticles

The adsorptions of H2 on metallocarbohedrene Ti8C12, and nanocrystal Ti14C13 are studied using first-principles calculations. The Ti atoms serve as catalyst to mediate the dissociation of H2 to form carbon hydrides, which otherwise would not form. Ti atoms on the surface of the nanocarbides are capable of coordinating with multiple dihydrogen ligands. High hydrogen capacities, 6.1 wt% for Ti8C12 and 7.7 wt% for Ti14C13, were obtained with more than 80% of the H bound in the energy range between 0.17 and 0.89 eV/H2. Once the nanoparticles form a macroscopic material, the amount of chemisorbed hydrogen decreases, but additional hydrogen molecules is then up-taken through physisorption. Our study suggests that TiC nanoparticles have potential for H storage at near ambient conditions.