Confined N-CoSe2 active sites boost bifunctional oxygen electrocatalysis for rechargeable Zn–air batteries

Abstract

Designing highly active electrocatalysts that are inexpensive, highly efficient, and durable for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc–air batteries (ZABs) is vital. A peapod-like CoSe2@NC bifunctional electrocatalyst is successfully fabricated herein by confining CoSe2 nanoparticles (NPs) to one-dimensional (1D) N-doped carbon (NC) nanorods based on a polyaniline encapsulation strategy. The electronic coupling role between NC and CoSe2 is revealed via X-ray photoelectron spectroscopy and synchrotron radiation X-ray absorption spectroscopy. In situ Raman spectroscopy is conducted to examine the structure of CoSe2@NC under the OER in an alkaline electrolyte. The peapod-like CoSe2@NC nanorods exhibit superior activity towards the ORR (E1/2 = 0.83 V) and OER (η = 340 mV @10 mA cm−2) in a 0.1 mol L−1 KOH solution. The as-assembled rechargeable ZAB achieves a large peak power density of 137.1 mW cm−2 and outstanding stability for 500 cycles at 10 mA cm−2. The encapsulation of CoSe2 NPs in the NC shells impedes their aggregation and corrosion during the ORR and OER processes. Experimental and DFT-based computational analyses assist in ascribing the outstanding bifunctional catalytic performance to the formation of N-CoSe2 active sites. These results provide a facile pathway for the development of efficient bifunctional electrocatalysts for high-performance rechargeable metal–air batteries.