Nanosensor for Hydrogen Detection and High‐Resolution Electrochemical Imaging

Electrochemical sensors for hydrogen can be useful for development and optimization of water electrolyzers and fuel cells based on hydrogen evolution and oxidation reactions (HER and HOR). A nanometer‐sized hydrogen sensor used as a tip in the scanning electrochemical microscope (SECM) can probe HER and HOR electrocatalysts and photocatalysts at the nanoscale. However, Pt tips and chemically modified nanoelectrodes previously employed for hydrogen sensing suffer from surface passivation, low amperometric signal, and stability issues. Here, the preparation of hydrogen sensors by covalently attaching ferrocene groups to the surface of Pt or carbon nanoelectrodes through oxidation of ferroceneacetate ions is reported. Mediated oxidation of hydrogen at surface‐modified nanoelectrodes produces measurable and stable current suitable for amperometric measurements and SECM imaging.