Catalase-like Fe Nanoparticles and Single Atoms Catalysts with Boosted Activity and Stability of Oxygen Reduction for Pesticide Detection

Although oxygen reduction reaction (ORR) as an effective signal amplification strategy has been extensively investigated for the improvement of sensitivity of electrochemical sensors, their activity and stability are still a great challenge. Herein, single-atom Fe (FeSA) and Fe nanoparticles (FeNP) on nitrogen-doped carbon (FeSA/FeNP) catalysts demonstrate a highly active and stable ORR performance, thus achieving the sensitive and stable electrochemical sensing of organophosphorus pesticides (OPs). Experimental investigations indicate that FeNP in FeSA/FeNP can improve the ORR activity by adjusting the electronic structure of FeSA active sites. Besides, owing to the excellent catalase-like activity, FeSA/FeNP can rapidly consume in situ generated H₂O₂ in the ORR process and avoid the leakage of active sites, thereby improving the stability of ORR. Utilizing the excellent ORR performance of FeSA/FeNP, an electrochemical sensor for OPs is established based on the thiocholine-induced poison of the active sites, demonstrating satisfactory sensitivity and stability. This work provides new insight into the design of high performance ORR catalysts for sensitive and stable electrochemical sensing.