| 초록 |
Single atom catalysts are in the spotlight for their high durability and high metal utilization. However, The role of pyrrole N and pyridine N in various studies conducted on single atom catalysts is still controversial. Herein, we synthesize two types of crumpled graphene-based Mn single-atom electrocatalysts and report the performance improvement upon introduction of pyrrole-type nitrogen in acidic ORR. Operando XAS indicated faster ORR progression in electrocatalysts containing Mn bound to pyrrole type N, suggesting that local atoms have better electron structure. DFT calculation indicated different spin state of Mn combined with pyridine type N and pyrrole type N, which could approach the cause of improved performance. The high spin state of Mn combined with pyrrole type N reduces the barrier energy for formation of the Mn-O intermediate by controlling the adsorption strength. These elucidations suggest the effect of spin states on ORR performance at the atomic level, which provides a new design strategy to improve the performance by controlling the spin state of the active site in various electrocatalysts. |
