N-doped carbon confined ternary Pt2NiCo intermetallics for efficient oxygen reduction reaction

Abstract

Developing high performance electrocatalysts for the cathodic oxygen reduction reaction (ORR) is essential for the widespread application of fuel cells. Herein, a promising Pt₂NiCo atomic ordered ternary intermetallic compound with N-doped carbon layer coating (o-Pt₂NiCo@NC) has been synthesized via a facile method and applied in acidic ORR. The confinement effect provided by the carbon layer not only inhibits the agglomeration and sintering of intermetallic nanoparticles during high temperature process but also provides adequate protection for the nanoparticles, mitigating the aggregation, detachment and poisoning of nanoparticles during the electrochemical process. As a result, the o-Pt₂NiCo@NC demonstrates a mass activity (MA) and specific activity (SA) of 0.65 A/mg_Pt and 1.41 mA/cm_Pt² in 0.1 mol/L HClO₄, respectively. In addition, after 30,000 potential cycles from 0.6 V to 1.0 V, the MA of o-Pt₂NiCo@NC shows much lower decrease than the disordered Pt₂NiCo alloy and Pt/C. Even cycling at high potential cycles of 1.5 V for 10,000 cycles, the MA still retains ∼70 %, demonstrating superior long-term durability. Furthermore, the o-Pt₂NiCo@NC also exhibits strong tolerance to CO, SO_x, and PO_x molecules in toxicity tolerance tests. The strategy in this work provides a novel insight for the development of ORR catalysts with high catalytic activity, durability and toxicity tolerance.