Insights into Ferrocene-Mediated Nitric Oxide Sensing - Elucidation of Mechanism and Isolation of Intermediate

An amperometric nitric oxide (NO) sensor based on a ferrocene methanol functionalized electrode was fabricated. The sensor could work at low over potential with a detection limit of 50 nM. The sensor exhibited excellent analytical performance, including a NO sensitivity of 6 μA nM−1 cm−2. The surface coverage of ferrocence on the modified electrode was calculated to be 2.06 × 10−10 mol cm−2. The heterogeneous rate constant calculated for ferrocene mediated NO reduction was found to be 3.5 × 105 cm3 mol−1 s−1. Further, the blue colored intermediate (Ferrocene hyponitrite) obtained during chemical and electrochemical reduction of NO mediated by ferrocene was isolated and characterized spectroscopically. Nitrous oxide (N2O), the final product of electrochemical reduction of NO was characterized using GC-MS. The mechanism of ferrocene-mediated nitric oxide reduction was found to be similar to biological NO reduction exhibited by the enzymes.