Precursor-templated synthesis of thermodynamically unfavored platinum nanoplates for the oxygen reduction reaction

Abstract

Controlling the shape of Pt-based nanomaterials is a major strategy to enhance the electrocatalytic performance towards the oxygen reduction reaction (ORR). Since the Pt (111) facet exhibits desirable electrochemical properties, Pt nanoplates enclosed by {111} facets are promising candidates. However, plate-shaped Pt crystals have thermodynamically unfavored structures, making syntheses challenging. Here we report a novel precursor-templated route to synthesize Pt nanoplates. Specifically, precipitated (NH₄)₂PtCl₆ prepared in aqueous solution is used as the Pt precursor followed by the addition of NaBH₄ as a reducing agent. With domain matching epitaxy, Pt nanoplates grow on the surface of the precipitated precursor, selectively exposing the {111} facets. Compared to those of commercial Pt/C at 0.90 and 0.85 V, the ORR properties of Pt nanoplates display a 1.5- and 5.2-fold enhancement in the mass activity, and a 3.3- and 11.6-fold enhancement in the specific activity, respectively. The superior ORR activities and the unique shape of Pt nanoplates are maintained for at least 5000 potential cycles.