Hydrogen-Bond-Promoted ORR Mechanism in P-Doped Fe–N–C Materials
Bing Li, Chunsheng Shi, Naiqin Zhao, Enzuo Liu
Abstract
P-doping has been widely adopted in M–N–C materials to enhance the catalytic activity of oxygen reduction reaction (ORR). However, the ORR mechanism of P-doping remains elusive. Herein, based on the first-principles calculations, the stability of P-doped FeN 4 is studied, and surface coverage versus potential is determined by the microkinetic model. It is revealed that the O *P coverage is stable at full potential due to the strong oxygen adsorption of P dopants, resulting in the hydrogen bond forming between OH *Fe and O *P . Thereby, the hydrogen-bond-promoted ORR mechanism is discovered. That is, the hydrogen bond between OH *Fe –O *P favors axial OH ligands covering at the broad potential range and thus promotes the ORR performance of FeN 4 both thermodynamically and kinetically. The core of the hydrogen-bond-regulated mechanism is that the oxygen species introduced by doping atoms will impact the ORR process at metal sites, and the methodology can also be applied to study other heteroatom-doped single-atom electrocatalysts.