Toward the Long-Term Stability of Cobalt Benzoate Confined Highly Dispersed PtCo Alloy Supported on a Nitrogen-Doped Carbon Nanosheet/Fe3C Nanoparticle Hybrid as a Multifunctional Catalyst for Zinc-Air Batteries.

Abstract

This work reports a new type of platinum-based heterostructural electrode catalyst that highly dispersed PtCo alloy nanoparticles (NPs) confined in cobalt benzoate (Co-BA) nanowires are supported on a nitrogen-doped ultra-thin carbon nanosheet/Fe3C hybrid (PtCo@Co-BA-Fe3C/NC) to show high electrochemical activity and long-term stability. One-dimensional Co-BA nanowires could alleviate the shedding and agglomeration of PtCo alloy NPs during the reaction so as to achieve satisfactory long-term durability. Moreover, the synergistic effect at the interface optimizes the surface electronic structure and prominently accelerates the electrochemical kinetics. The oxygen reduction reaction half-wave potential is 0.923 V, and the oxygen evolution reaction under the condition of 10 mA•cm-2 is 1.48 V. Higher power density (263.12 mW•cm-2), narrowed voltage gap (0.49 V), and specific capacity (808.5 mAh•g-1) for PtCo@Co-BA-Fe3C/NC in Zn-air batteries are achieved with long-term cycling measurements over 776 h, which is obviously better than the Pt/C + RuO2 catalyst. The interfacial electronic interaction of PtCo@Co-BA-Fe3C/NC is investigated, which can accelerate electron transfer from Fe to Pt. Density functional theory calculations also indicate that the interfacial potential regulates the binding energies of the intermediates to achieve the best performance.