F Doping-Induced Multicomponent Synergistic Active Site Construction toward High-Efficiency Bifunctional Oxygen Electrocatalysis for Rechargeable Zn-Air Batteries.

Abstract

The commercialization of rechargeable Zn-air batteries (ZABs) relies on the material innovation to accelerate the sluggish oxygen electrocatalysis kinetics. Due to the differentiated mechanisms of reverse processes, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), rationally integrating dual sites for bifunctional oxygen electrocatalysis is prerequisite yet remains challenging. Herein, multicomponent synergistic active sites within highly graphitic carbon substrate are exquisitely constructed, which is accomplished by fluorine (F) modulation strategy. The incorporation of F dopants facilitates pyridinic N formation for anchoring single metal sites, thus guaranteeing the coexistence of sufficient M-Nx sites and metal nanoparticles toward bifunctional oxygen electrocatalysis. As a result, the optimal catalyst, denoted as F NH2-FeNi-800, outperforms commercial Pt/C+RuO2 with smaller gap between Ej = 10 and E1/2 (ΔE) of 0.63V (vs 0.7V for Pt/C+RuO2), demonstrating its superior bifunctionality. Beyond that, its superiority is validated in homemade rechargeable ZABs. ZABs assembled using F NH2-FeNi-800 as the air cathode delivers higher peak power density (123.8mW cm-2) and long-cycle lifetime (over 660 cycles) in comparison with Pt/C@RuO2 (68.8mW cm-2; 300 cycles). The finding not only affords a highly promising oxygen electrocatalyst, but also opens an avenue to constructing multifunctional active sites for heterogeneous catalysts.