Sub-15 nm Pd@PtCu concave octahedron with enriched atomic steps as enhanced oxygen reduction electrocatalyst

Catalyst nanoparticles with enriched atomic steps structure can offer higher catalytic performance. Nevertheless, the reported sizes of PtCu nanoparticles with enriched atomic steps surface are usually larger than 30 nm or even hundreds of nanometres, which need great reduction for further improved catalytic performance. In this work, Pd nanocubes are used as seeds for mediating growth of 13.7 nm Pd@PtCu concave octahedrons with enriched atomic steps surface. Towards oxygen reduction reaction , the specific activity at 0.9 V for the Pd@PtCu concave octahedral catalyst is 3.36 mA cm-2 Pt, which is 2.6 and 11.4 times higher than that of Pd@PtCu octahedron (1.31 mA cm-2 Pt) and commercial Pt/C (0.29 mA cm-2 Pt) catalyst, respectively. The dramatic performance enhancement can be ascribed to the reduced particle sizes for increased electrochemically active surface area (ECSA), a high density of atomic steps and a large number of concave sites as highly active catalytic reaction centers to break O–O bonds. This work demonstrates a new approach to synthesize a superior electroactive catalyst, holding a great promise for practical applications in high-performance and low-temperature fuel cells.