Single-Atom to Single-Atom Grafting of Pt-1 onto Fe-N-4 Center: Pt-1@Fe-N-C Multifunctional Electrocatalyst with Significantly Enhanced Properties

摘要

Nonprecious metal catalysts (NPMCs) Fe-N-C are promising alternatives to noble metal Pt as the oxygen reduction reaction (ORR) catalysts for proton-exchange-membrane fuel cells. Herein, a new modulation strategy is reported to the active moiety FeN4 via a precise "single-atom to single-atom" grafting of a Pt atom onto the Fe center through a bridging oxygen molecule, creating a new active moiety of Pt-1-O-2-Fe-1-N-4. The modulated Fe-N-C exhibits remarkably improved ORR stabilities in acidic media. Moreover, it shows unexpectedly high catalytic activities toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with overpotentials of 310 mV for OER in alkaline solution and 60 mV for HER in acidic media at a current density of 10 mA cm(-2), outperforming the benchmark RuO2 and comparable with Pt/C(20%), respectively. The enhanced multifunctional electrocatalytic properties are associated with the newly constructed active moiety Pt-1-O-2-Fe-1-N-4, which protects Fe sites from harmful species. Density functional theory calculations reveal the synergy in the new active moiety, which promotes the proton adsorption and reduction kinetics. In addition, the grafted Pt-1-O-2- dangling bonds may boost the OER activity. This study paves a new way to improve and extend NPMCs electrocatalytic properties through a precisely single-atom to single-atom grafting strategy.