Weakening hydroxyl intermediate binding achieves efficient oxygen reduction reaction for electrochemical cell sensing

The 4-electron oxygen reduction reaction (ORR) as an effective signal amplification strategy has been widely utilized to enhance the sensitivity of electrochemical sensor. However, achieving activity and stability of ORR remains a critical challenge. The strong adsorption of OH* frequently blocks the active sites, which is a common phenomenon that diminishes both catalytic activity and stability. This work designed a Pt-based catalyst that can alleviate the OH* poisoning effect to achieve high activity and stability and provides a foundation for the rational design for electrochemical sensing applications.

Here, PtCo intermetallic compounds (IMCs) and CoN_x sites on nitrogen-doped carbon skeleton (PtCo-CoN_x/NC) is synthesized by a simple impregnation reduction method. The interaction between PtCo intermetallics and the CoN_x/NC support contributes to enhanced ORR activity and stability. In situ FTIR spectroscopy and electrochemical measurements reveal that the PtCo-CoN_x/NC catalyst reshapes the electronic environment of Pt and optimizes its d-band structure. This structural modulation effectively facilitates the desorption of OH* and alleviates surface blockage, thereby enhancing both the activity and stability of the ORR. Based on the -SH poisoning effect for active site and the differences in the GSH content within different cells, the designed electrochemical sensor completes the partitioning of multiple types of cells. The developed PtCo-CoN_x/NC electrochemical sensor exhibits excellent sensitivity, stability, and capability to distinguish between normal and tumor cells.

This work innovatively constructs synergistic PtCo intermetallic and CoN_x sites that promote OH* desorption by optimizing Pt electronic structure, mitigating catalyst poisoning. The strategy significantly enhances ORR activity and stability and the designed sensor achieves glutathione detection and cell distinction through a thiol-induced active site poisoning effect. This work providing critical material design and mechanistic insights for developing highly sensitive and stable electrochemical sensors.