Nonmetallic phosphorus alloying to regulate the oxygen reduction mechanisms of platinum catalyst

Abstract

Platinum (Pt) nanoparticle catalysts remain the most popular cathode materials for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. Non-metallic alloying of Pt has become an emerging strategy to improve electrocatalytic performance, however, the electrocatalytic ORR mechanisms still need to be understood for further improvement toward practical application. Herein, a rapid microwave reduction method is employed for alloying phosphorous (P) into Pt to form a carbon supported phosphorus-alloyed Pt nanoparticle catalyst (P-Pt/C), which demonstrates the ability to replace commercial Pt/C. By a combination of density functional theory calculations and in-situ electrochemical Raman spectroscopy, the regulation role of P-alloying in the electrocatalytic mechanisms is revealed. It is found that the nearby Pt atoms can convert the ORR pathway from associative one to dissociative one, exhibiting a spontaneous dissociation of *OOH intermediate to *OH and *O species as well as a change of potential determining step to *O protonation. Furthermore, the strategy of large-scale economic synthesis of such alloying Pt-based catalyst is also established, demonstrated by a gram-level synthesis per batch. This study puts insight into the electrocatalytic ORR fundamentals of Pt-alloying with non-metals and provides a basis for the reasonable design and synthesis of efficient nonmetals-alloyed Pt catalysts.