摘要
Surface tailoring as well as inner structure design at the atomic scale are of primary importance for the activity and durability of nanocatalysts (NCs) in electrochemical applications. In this study, a novel structural candidate containing a Cu core and Pt cluster decorated Pd shell with a balance struck between the performance and cost considerations for the oxygen reduction reaction (ORR) is proposed. The carbon nanotube supported NCs are synthesized using a wet chemical reduction method with different ratios of Pt from 5 to 14 wt%. Our results demonstrate a robust assessment for programming the ORR performance by Pt loading control in the NCs. For the optimum case (∼5.0 wt% of Pt), the mass activity (M.A.) is ∼639 mA mg . This value is improved by 9-folds compared to that of commercial Pt NC (J.M.-Pt/C) at 0.85 V vs. RHE and can be attributed to the formation of a high density of surface truncations in the NC surface. When the Pt loading is ∼9 wt%, the NC forms multi-faceted twin particles with low surface defects and thus has the highest stability (+/- 0.5% of current vibration) in an accelerated degradation test (ADT) among the experimental samples. Further increasing Pt to 14 wt%, restructures the NC into a local ordered crystal with certain amounts of Pt island clusters in the surface. Such a phenomenon results in a vibration of the current density by surface restructure upon oxidation and reduction of Pt oxides in a ADT test and possesses a residual current density of 92% compared to its original value after 40 k cycles. Most importantly, our observations bring fundamental and practical insights into the role of surface defects in electrocatalysis and present a new strategy to surmount a dilemma between the reliability and activity of ORR NCs.