Direct observation and force modulation of single-bond reactions at the ion/metal interface

Elucidating the mechanisms of ion-involved interfacial reactions at the single-bond level is important for understanding interface science. Here, the reaction between pyridine ions and protons at the solid-liquid interface is studied in situ using a single-molecule conductance measurement technique. By manipulating the interfacial electrostatic potential, an ion/metal interfacial state relying on electrostatic interactions has been discovered, comprising terminal group-hydrogen-gold in specific. The reversible interfacial protonation reaction mechanism is revealed in situ at the single-bond level based on this interfacial state. Experiment results also indicate that external forces can effectively regulate this ion-involved interfacial reaction. This work provides a single-bond approach for in situ investigations of ion-involved interfacial reactions with an ion/metal interfacial state, thus promoting the development of interface science.