High‐Shell Sulfur Doping Enhances Mn‐N4 Spin States and Boosts Oxygen Reduction Reaction Performance in both Acidic and Alkaline Media

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 21; no. 11; pp. e2411678 - n/a
• Main Authors: Li, Yuan, Wu, Hao‐Ran, Yu, Yue, Chen, Miao‐Ying, Zhao, Kuang‐Min, Li, Wei‐Dong, Rong, Si‐Yu, Xue, Dong‐ping, Zhang, Jia‐Nan, Lu, Bang‐An
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.03.2025
• Subjects: Catalysts; Chemical reduction; Doping; Durability; electron‐withdrawing effects; Energy conversion; Fuel cells; Iron; Manganese; Metal air batteries; M‐N‐C catalysts; Nitrogen; oxygen reduction reaction; Oxygen reduction reactions; Platinum metals; Sulfur; sulfur‐anion coordination; Zinc-oxygen batteries
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202411678

The development of platinum group metal‐free catalysts for the oxygen reduction reaction (ORR) is critical to advancing sustainable energy conversion technologies. Manganese (Mn)‐based catalysts, known for their reduced toxicity and promising durability, have traditionally exhibited lower ORR activity compared to state‐of‐the‐art iron‐nitrogen‐carbon (Fe‐N‐C) catalysts. In this study, a highly efficient Mn‐N‐C‐S catalyst is presented, engineered through a sulfur‐mediated high‐shell coordinated doping strategy, that markedly enhances ORR activity and stability. The Mn‐N‐C‐S catalyst achieves a record‐high half‐wave potential of 0.94 V in alkaline media, among the highest values reported for Mn‐based catalysts. Additionally, in acidic media, it exhibits a half‐wave potential of 0.80 V, placing it among the top‐performing M‐N‐C catalysts. The catalyst also demonstrates a high peak power density of 0.82 W cm−2 in H2‐O2 fuel cells and 0.264 W cm−2 in Zn‐air batteries, outperforming previously reported Mn‐based catalysts. Both experimental findings and theoretical computations suggest that the high‐shell S‐doping can increase the spin density of Mn sites, strengthen Mn‐N bonds, and thereby improve the durability of Mn‐N4 sites. This work underscores the effectiveness of high‐shell sulfur doping and paving the way for their deployment in the cathodes of fuel cells and metal‐air batteries. The catalyst is synthesized by a sulfur‐mediated two‐step adsorption‐pyrolysis strategy, which significantly increases the density of MnN4 sites. The high‐shell coordinated S doping can increase the spin density of Mn‐N4, weaken the oxygen intermediate affinity, and strengthen the Mn‐N bonds. The Mn‐N‐C‐S catalyst delivers record‐high power density and extraordinary stability in H2‐O2 fuel cells and Zn‐air batteries.