Effect of functionalization degree of graphene oxide on Pd dispersion of Pd/PEAN-functionalized GO

Surface functionalization of graphene oxide(GO) represents a direct and highly effective approach to improve the dispersion and particle size distribution of palladium nanoparticles on the surface of the GO. Pd/4-ethynylaniline-functionalized GO(Pd/PGO) with highly dispersed Pd was prepared by using 4-ethynylaniline (PEAN) as a modifier, which would strengthen the metal-support interaction (MSI) between Pd and GO. Characterizations confirm that PEAN is successfully grafted onto GO via epoxy ring-opening and amidation reaction. Transmission electron microscopy (TEM) and inductively coupled plasma (ICP) results confirm that the average particle size of Pd nanoparticles on the reduced graphene oxide (RGO) surface is 23.0 nm, with a loading rate of 6.23%. As the degree of functionalization increases, the average particle size of Pd nanoparticles loaded on the PGO7 surface decreases to 5.2 nm, while the loading rate rises to 8.73%. Therefore, it can be concluded that a high degree of PEAN functionalization enhances the loading rate of Pd nanoparticles on the GO surface while improving dispersion and particle size distribution. This study provides a direct and effective approach for designing metal catalysts with high dispersion and narrow particle size distribution. Moreover, the π-π conjugated skeleton of PEAN overlaps with the sp2 carbon network of GO, which facilitates electron transfer between GO and Pd.