Self-Template Synthesis of Atomically Dispersed Fe/N-Codoped Nanocarbon as Efficient Bifunctional Alkaline Oxygen Electrocatalyst

High performance and durable bifunctional oxygen electrocatalysts are of great importance for the commercial application of environmentally friendly and sustainable energy through electrochemical devices such as rechargeable Zn–air batteries and fuel cells. Highly distributed catalysts with maximum atomic utilization are considered to be a promising alternative for current noble-metal-based catalysts. Herein, a self-template synthesis and polypyrrole encapsulated method is used to prepare atomically dispersed Fe/N-codoped double-shelled hollow carbon nanospheres (denoted as AD-Fe/N-C-900). Compared with nanoparticle dispersed Fe/N-codoped nanocarbon (NP-Fe/N-C-900) and N-doped nanocarbon (N-C-900), as-prepared AD-Fe/N-C-900 with mesoporous structure and high density of Fe–Nx active sites exhibits high ORR activity (E1/2 = 0.927 V vs RHE) and high OER performance (Ej=10 = 1.582 V vs RHE) in 0.1 M NaOH solution. The potential gap (ΔE = Ej=10 – E1/2) is 0.655 V, which is better than that of most highly active bifunctional electrocatalysts for oxygen electrode reported so far. The remarkable electrocatalytic performance of AD-Fe/N-C-900 might be attributed to the high content of mesopores, high density of Fe–Nx active sites, and robust double-shelled hollow structure, indicating its feasibility and potential in practical applications.