Confined Pyrolysis within a Nanochannel to Form a Highly Efficient Single Iron Site Catalyst for Zn–Air Batteries

Structural engineering of atomic-scaled metal/N–C catalysts is crucial yet challenging in enhancing their performance for the oxygen reduction reaction (ORR). Herein, we demonstrate exclusive single iron sites in periodic mesoporous nitrogen-doped carbon through an efficient template-directed pyrolysis strategy. The channel in SBA-15 was introduced to give a large specific area and uniform mesopore, providing abundant exposed active sites for the ORR. As a result, the optimal single-atom Fe catalyst exhibits a more positive onset potential (1.03 V vs RHE) and half-wave potential (0.902 V vs RHE) than those of a commercial Pt/C catalyst in an alkaline medium. For the single-atom Fe catalyst after 20000 s, 93.6% of the current at 0.8 V vs RHE can be retained, demonstrating its good stability. Additionally, when utilized to assemble the air electrode of a primary zinc–air battery, the obtained Fe single-atoms catalyst provides high voltage and durability, indicating its practical applicability.