Real-time optical monitoring of diazonium electrografting: imaging nanometric layer growth and redox activity.

Abstract

Diazonium electrografting provides a versatile route to robust molecular interfaces for applications ranging from sensing to catalysis, yet the formation and electrochemical behavior of the resulting nanometric films remain difficult to monitor in real time because of their extremely faint optical signatures. Here, we demonstrate that micromirror-enhanced optical microscopy (MEOM) enables local monitoring of diazonium electrografting and interfacial redox processes on transparent conductive substrates. By locally amplifying the collection of photons, MEOM allows real-time imaging of nanometric Ru-bis-terpyridine diazonium film growth while revealing the influence of interfacial mass transport on the grafting mechanism. Beyond film formation, the method provides highly sensitive optical monitoring of the redox switching of ultrathin grafted layers, establishing a direct correlation between optical contrast and electrochemical activity. These results introduce MEOM as a general operando imaging platform for probing the growth, structure, and functional dynamics of molecularly thin electroactive interfaces, opening new opportunities for the investigation of surface-confined materials in electrochemistry, catalysis, and molecular electronics.

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