Three-dimensional graphene aerogel supported Ir nanocomposite as a highly efficient catalyst for chemoselective cinnamaldehyde hydrogenation

Abstract

A three-dimensional graphene aerogel-supported Ir (Ir/GA) nanocomposite with interconnected porous framework and high dispersion of Ir nanoparticles is synthesized via a simple yet effective “co-reduction self-assembly” strategy, in which the chemical co-reduction of graphene oxide and H2IrCl6 occurs in the presence of glycerol and Ir is directly incorporated onto the reduced graphene oxide nanosheets. The Ir/GA possesses rich hierarchical porosity, a low amount of oxygen-containing functional groups, and a certain amount of Irδ- species, which notably improve the accessibility to both sides of the resulting reduced graphene oxide nanosheets, number of active Ir sites, electron transfer ability, and affinity of active Ir with CO band. As a catalyst in chemoselective cinnamaldehyde (CMA) hydrogenation towards cinnamyl alcohol (CMO), the Ir/GA shows satisfactory CMA conversion of 85.8% and CMO selectivity of 83.2% with a high TOF activity of yielding CMO up to 17.5 h−1 at reaction time of 1 h. Moreover, the Ir/GA delivers good catalytic durability even after seven successive cycles without pronounced activity deterioration. This study highlights the exciting possibility to synthesize highly efficient graphene-supported precious metal catalysts with multiscale control by overall consideration in mass transportation, metal dispersion, metal-support interactions, and electronic density of active sites for chemoselective CMA hydrogenation.