A general and scalable approach to produce nanoporous alloy nanowires with rugged ligaments for enhanced electrocatalysis

Abstract

Nanoporous metal nanowires with large surface areas, and a high density of defect sites play an important role in catalysis. Here, a general and scalable one-step dealloying strategy is developed to prepare nanoporous alloy nanowires with controllable compositions by manipulating the grain size, structure and composition of bulk Cu-based precursor alloys. We prepared PtCuAu nanoporous nanowires with a diameter of 200–500 nm and tunable composition by dealloying a diluted Pt₁Au_0.5Cu_98.5 single-phase alloy with nanoscale column-like-structured grains. Material characterization suggests that the formation of separated nanowires is due to the large-scale shrinkage of the column-structured grains during dealloying of Cu, which also generates ultrafine nanopores and rugged alloy ligaments with a high density of defect sites in the nanowires. When used as a cathodic catalyst for the oxygen reduction reaction (ORR), the PtCuAu nanoporous nanowires exhibit a composition-dependent catalytic performance. The 8.0 M HNO₃ dealloyed sample exhibits a specific activity of 4.12 mA cm⁻² at 0.9 V, which is more than 14 times that of commercial Pt/C. With the advantages of being easy to scale up, highly reproducible and controllable, the fabrication strategy holds great promise to prepare nanocatalysts for fuel cells.