Revealing the interfacial electron modulation effect of CoFe alloys with CoC encapsulated in N-doped CNTs for superior oxygen reduction

Abstract

Rationally designing and developing robust and durable electrocatalytic materials for oxygen reduction/evolution are essential for metal−air batteries. Herein, an effective approach is proposed to fabricate high-performance electrocatalysts based on CoFe alloy and CoC X nanoparticles sandwiched in nitrogen-doped carbon nanotubes. The preparation of CoFe−CoC X @NCNT is achieved by the calcination of CoFe 2 O 4 spinel and dicyandiamide under reducing atmosphere. The CoFe−CoC X @NCNT catalyst exhibits remarkable oxygen reduction reaction (ORR) performance with the onset and half-wave potential of 1.01 ​V and 0.89 ​V, respectively, exceeding the commercial Pt/C catalyst. Furthermore, the Zn−air battery using CoFe−CoC X @NCNT as air cathode shows a power density of 175 ​mW ​cm −2 , which is also higher than that of the industrial Pt/C ​+ ​RuO 2 . The super electrocatalytic performance is attributed to the multiple heterointerface and strong coupling effect among CoFe, CoC X , and NCNT, which can regulate conductivity and electron structure of the catalyst. This study supplies a practical strategy to exploit active and low-cost catalytic material for Zn−air batteries, and presents an in-depth insight into the designing of efficient green energy storage devices. Herein, the CoFe-CoC X @NCNT exhibits an outstanding ORR performance with onset potential of 1.01 ​V and half-wave potential of 0.89 ​V, exceeding the commercial Pt/C catalyst. Furthermore, the Zn-air battery performance assembled by CoFe-CoC X @NCNT shows the power density of 175 ​mW ​cm −2 is also better than that of the commercial Pt/C ​+ ​RuO 2 . The excellent performance is attributed to the multiple heterogeneous interfaces and strong coupling between CoFe alloy, CoC X , and NCNT, which are helpful to drive fast reaction kinetics and regulate local coordination environment and electronic structure. This work provides a new approach to design excellent active and low-cost catalysts for Zn-air batteries, which presents an in-depth insight into the development of efficient green energy storage devices.