Anisotropic growth of PtFe nanoclusters induced by lattice-mismatch: Efficient catalysts for oxidation of biopolyols to carboxylic acid derivatives

Abstract

By exploiting the large difference in lattice constants between Pt and Fe metals, anisotropic growth of bimetallic PtFe clusters with high index numbers has been prepared to investigate their catalytic performance in oxidation of biopolyols. Surface characterization using transmission electron microscopy shows that etching effects caused by Fe3+ and anisotropic growth induced by lattice mismatch contributed to the final nanocrystal geometry. The bimetallic PtFe heterocluster is shown to exhibit an unprecedented sixfold enhanced catalytic activity and threefold higher selectivity compared to monometallic Pt catalyst, in oxidation of biomass-derived polyols to dicarboxylic acids. A detailed study on structure-dependent kinetics of oxidation of glycerol, based on concentration–time profiles on Pt and PtFe catalysts, reveals that the presence of Fe in Pt catalysts significantly enhances the rate of oxidation and decreases the activation barriers for primary and secondary oxidation steps leading to enhanced catalytic activity and selectivity. The lattice mismatch methodology employed in this work provides an unique tool for designing high index catalytically active materials for various other industrial applications.