Hydrogen generation and hydrogenation reactions efficiently mediated by a thin film of reduced graphene oxide-grafted with carboxymethyl chitosan and Ag nanoparticles

Abstract

In this work, we have investigated the use of a heterogeneous catalyst based on reduced graphene oxide-grafted with carboxymethyl chitosan (rGO-CMCHT) and silver nanoparticles (AgNPs) for hydrogen generation through straightforward borohydride decomposition reaction. Thus, an rGO-CMCHT thin film containing AgNPs was successfully prepared by using a dip-coating technique. Characterization analysis indicated that rGO-CMCHT enhances the catalytic activity of AgNPs due to its intrinsic electric capacity (i.e., low electron-mobility resistivity). The experimental results showed that the prepared thin film has a remarkable catalytic activity that boosts hydrogen generation (maximum rate 180 × 102 mL min−1 g−1), achieving TOF values (480 min−1) that exceed the previously reported data. High TOF values were also obtained in aqueous and non-aqueous media using low amounts of catalyst, confirming its versatility. Reuse experiments demonstrated that thin film could be recycled and reused for at least ten consecutive reactions without losing catalytic efficiency. Spectroscopic analyses showed that AgNPs were not leached in the reaction medium after the reuse cycles, indicating that rGO-CMCHT stabilizes the nanoparticles efficiently. Finally, the prepared thin film also showed excellent catalytic performance catalytic towards the reduction of nitroaromatic compounds in aqueous and non-aqueous media, confirming its versatility for hydrogen production and hydrogenation reactions.