Polymetal-Chelated Fabrication of Bimetallic Nanophosphides as Electrocatalysts for Zinc-Air Batteries.

ABSTRACT

Bimetallic phosphides are considered as promising electrocatalysts for zinc-air batteries toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). To address the semi-conductor inherent low electronic conductivity and catalytic activity, a polymetal-chelated strategy is employed to in situ fabricate bimetallic nanophosphides within carbon matrix anchoring by chemical bonding. The employment of biomolecule polydopamine (PDA) efficiently anchors various transition metal ions due to its strong chelating capability via inherent functional groups. Furthermore, the chelation of multi-metal ion is proved to promote the formation of graphitic nitrogen. The bimetallic FexCoyP phosphides nanoparticles are intimately encapsulated in carbon matrix through in situ carbonization and phosphatization processes. When utilized in Zinc-air batteries, Fe0.20Co0.80P anchored within N, P co-doped sub-microsphere (Fe0.20Co0.80P /PNC) exhibit a maximum power density of 167 mW cm-2 and cycle life up to 270 cycles, with a round-trip voltage of 0.955 V. The mechanisms for catalytic activity passivation are ascribed to the etching of nitrogen and oxidation of phosphorus in carbon matrix, as well as the oxidation of the surface phosphide on the sub-microspheres. This study presents a promising candidate for advancing the further development of energy conversation catalysis.