Cu nanoclusters activating ultrafine Fe3N nanoparticles via the Mott-Schottky effect for rechargeable zinc-air batteries

The rational design and synthesis of cost-effective bifunctional oxygen electrocatalysts is crucial for the large-scale commercial applications of rechargeable zinc-air batteries. In this work, the CuNCs/Fe3N-NPCF catalyst was constructed by anchoring the metallic Cu/Fe3N ensembles with different sizes onto N-doped porous carbon nanosheets. The Mott-Schottky heterostructure formed by Fe3N nanoparticles and its surrounding Cu clusters enabled spontaneous electron transfer, which speeded up the electron supply from active sites to various oxygen intermediates. The electrophilic region on Cu side and the nucleophilic region on Fe3N side improved the adsorption of O2 and OH-, respectively. The CuNCs/Fe3N-NPCF exhibited onset potential of 0.98 V and low Tafel slope of 59.30 mV dec−1 in ORR, and overpotential of 282 mV at 10 mA cm−2 current density in OER. The CuNCs/Fe3N-NPCF-based zinc-air battery displayed the excellent catalytic activity and durability. These findings provided the guides in developing the efficient and stable Mott-Schottky bifunctional oxygen electrocatalysts.