Fe-single-atom-coupled Fe3C multifunctional catalysts on P-, F-, N-doped carbon nanotubes for stable Zn–air batteries with ultra-high power densities

Abstract

It is a challenge to develop low-cost, efficient, and stable multi-functional electrocatalysts for the oxygen evolution reaction (OER), overall water splitting (OWS), oxygen reduction reaction (ORR), and zinc–air batteries (ZABs). To address such issues, for the first time, we rationally design and facilely construct iron-single-atom-coupled Fe₃C on P-, F-, N-triply doped carbon nanotubes (Fe_SAs-PFN-CNTs). Herein, the modulation of the Fe atom coordination environment, low loading of Fe₃C nanoparticles, and inclusion of heteroatom-doped CNTs facilitated ample proton-feeding and charge-transfer processes. As a result, the Fe_SAs-PFN-CNT catalyst delivers fast electrokinetics, exhibiting efficient OER (an overpotential (η₁₀) of 310 mV with 24 h stability), admirable OWS anode (325 mV (η₁₀) with 10 h stability), excellent ORR (an half-wave potential (E_1/2) of 0.88 V with 6 h stability), and outstanding ZAB (an open-circuit voltage of 1.49 V, high specific capacity of 781 mA h g_Zn⁻¹ (93.5% of the theoretical capacity of 835 mA h g_Zn⁻¹), and ultrahigh power density of 241 mW cm⁻²) performances, which is superior to those of benchmark electrocatalysts. In this regard, this work provides an excellent scalable multifunctional catalyst for the commercialization of low-cost, efficient, and stable electrocatalysts for application in oxygen catalysis and Zn–air batteries.