Precise regulation of pyrrole‐type single‐atom Mn‐N4 sites for superior pH‐universal oxygen reduction

Abstract

Abstract The study of atomically dispersed metal‐nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of N in combination with the metal elements. Inspired by the high catalytic activity and selectivity of natural enzymes, herein, we have designed and fabricated ultrathin carbon nanosheet‐supported Mn single‐atom catalysts (SACs) with a precise pyrrole‐type Mn‐N4 (PT‐MnN4) configuration using a bio‐mimicking strategy. The PT‐MnN4 SACs display outstanding oxygen reduction reaction (ORR) activity, with a half‐wave potential (E1/2) of 0.88 V (vs. revisible hydrogen electrode [RHE]) and extremely high stability in alkaline media. Moreover, superior ORR activities are also obtained, E1/2 of 0.73 V and 0.63 V in acid and neutral electrolytes, respectively, indicating the efficient pH‐universal ORR performances. The assembled zinc–air battery using the PT‐MnN4 SACs as air cathodes exhibits a high peak power density (175 mW cm−2) and long‐term stability up to 150 h, implying its promising application in metal–air batteries. This study has paved the way toward the rational design and precise regulation of single‐atom electrocatalysts.

Keywords

• oxygen reduction reaction
• pH‐universal
• pyrrole‐type N
• single‐atom catalysts
• Zn–air batteries