Enhancement mechanism of P dopant on atomically distributed FeN4P-C electrocatalyst over a wide pH range

Abstract

Heteroatom doping plays an essential role in improving the catalytic performance of electrocatalysts for oxygen reduction reaction (ORR). However, how to regulate heteroatom doping remains a significant challenge. This paper develops an efficient strategy by using a novel versatile chelating ligand to enhance P loading and expose more metal single Fe atom active sites of FeN4P-C catalyst. The electron distribution of active center is considerably changed by P doping, which significantly influences the catalytic ORR performance. The dopant P in the FeN4P-C catalyst induces a small number of d-electrons from t2g-orbitals around the Fermi level, making the interaction between Fe active site and O2 slightly more robust than in the FeN4C catalyst, as studied by DFT calculations. The as-prepared FeN4P-C catalyst exhibits excellent catalytic ORR activity in both acidic (with a half-wave potential of 0.760 V vs. RHE) and basic (with a half-wave potential of 0.885 V vs. RHE) conditions, which are superior to those of the commercial Pt/C (20 wt%) catalyst. Furthermore, this catalyst also demonstrates outstanding stability and good hydrogen peroxide and methanol tolerance. A Zinc-air battery(ZAB) assembled using the cathode catalyst has validated the high performance of this catalyst. This study provides an efficient method for generating well-defined single-atom active sites to improve catalytic performance and paves the way to identify coordinated single metal atom sites for electrocatalysis applications.