Synthesis of Pd nanonetworks with abundant defects for oxygen reduction electrocatalysis

Abstract

The Pd-based nanocatalysts have blossomed into a promising substitute for Pt-based nanocatalylsts due to its similar electronic structure, rather low price, and superior catalytic performance to that of Pt. Constructing abundant surface defects on the surface of Pd nanocatalysts will boost the activity and utilization efficiency of Pd. However, it remains a big challenge to construct surface defects on the surface of Pd nanocatalysts. Here we report a remarkably facile method for the preparation of three dimensional Pd nanonetworks with abundant defects, such as twin boundaries, distorted atoms and disordered atoms. These abundant defects on the surface of Pd nanonetworks are caused by the connection process among Pd nanoparticles. Compared with commercial Pd/C catalysts, the as-prepared Pd nanonetworks exhibit enhanced catalytic activity and stability toward the oxygen reduction reaction. It shows a mass activity of 0.152 A mg_Pd⁻¹ at 0.85 V versus the reversible hydrogen electrode, which is 4.0 times larger than that of the commercial Pd/C catalyst (0.038 A mg_Pd⁻¹). Meanwhile, these Pd nanonetworks also exhibit a specific activity of 0.449 mA cm⁻² at 0.85 V, 2.2 times larger than that of the commercial Pd/C catalyst (0.204 mA cm⁻²). This work suggests that the surface defects and three dimensional structure of Pd nanocatalysts can promote the catalytic activity and durability effectively for the oxygen reduction reaction.