Activity promotion of bifunctional catalysis by Se-doping and the application in rechargeable zinc-air batteries.

• Catalyst of Se-doped FeNiP nanoparticle embedded in a carbon matrix was synthesized. • The Se atoms doped in lattice of FeNiP crystal and modulated the surface OER sites. • The Se atoms also doped in the carbon matrix and improved the ORR performance. • Se elements acting as medium elements contribute to forming a compact composite. • The assembled solid-state zinc-air batteries were integrated as a 3 × 3 module. Efficient bifunctional catalysts capable of catalyzing both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are required for the air electrode. Herein, the Se-doped FeNiP nanoparticles/N, P dual-doped carbon composite catalysts (FeNiP/SeNPC-2) were developed. The Se elements combine with various elements to form a compact heterogeneous material. At the same time, the Se-doping have modulated the crystal and surface structures, which have improved the catalytic activities of ORR and OER. The overpotential of OER was significantly negatively shifted, accompanied by a significant positive shift of the onset potential of ORR. FeNiP/SeNPC-2 has displayed an overpotential of 269 mV at the current density of 10 mA cm−2 for OER, and with a high half-wave potential (0.86 V) of ORR. The liquid zinc-air battery assembled using FeNiP/SeNPC-2 exhibited a power density of 171 mW cm−2 and stably charge-discharge cycled for 150 h. The solid-state zinc-air battery exhibited a power density of 88 mW cm−2 and stably charge-discharge cycled for 42 h. Subsequently, the solid-state zinc-air batteries of cylindrical hollow design are integrated as modules for driving devices. [Display omitted] [ABSTRACT FROM AUTHOR]