Enhanced catalytic activity of monodispersed AgPd alloy nanoparticles assembled on mesoporous graphitic carbon nitride for the hydrolytic dehydrogenation of ammonia borane under sunlight

Abstract

We address the composition-controlled synthesis of monodispersed AgPd alloy nanoparticles (NPs), their assembly for the first time on mesoporous graphitic carbon nitride (mpg-C3N4), and the unprecedented catalysis of mpg-C3N4@AgPd in the hydrolytic dehydrogenation of ammonia borane (AB) at room temperature. Monodispersed AgPd alloy NPs were synthesized using a high-temperature organic-phase surfactant-assisted protocol comprising the co-reduction of silver(I) acetate and palladium(II) acetylacetonate in the presence of oleylamine, oleic acid, and 1-octadecene. This protocol allowed the synthesis of four different compositions of AgPd alloy NPs. The AgPd alloy NPs were then assembled on mpg-C3N4, reduced graphene oxide, and Ketjenblack using a liquid-phase self-assembly method. Among the three supports tested, the mpg-C3N4@AgPd catalysts provided the best activity because of the Mott–Schottky effect, which was driven by the favorable work function difference between mpg-C3N4 and the metal NPs. Moreover, the activity of the mpg-C3N4@AgPd catalyst was further enhanced by an acetic acid treatment (AAt), and a record initial turnover frequency of 94.1 mol(hydrogen)·mol (catalyst) −1 ·min−1 was obtained. Furthermore, the mpg-C3N4@Ag42Pd58-AAt catalyst also showed moderate durability for the hydrolysis of AB. This study also includes a wealth of kinetic data for the mpg-C3N4@AgPd-catalyzed hydrolysis of AB.