N‑Heterocyclic\nCarbene Overlayers on Mild Steel

Although\nthe functionalization of noble metals with N-heterocyclic\ncarbenes (NHCs) is well-known, the interactions of these versatile\nligands with common alloys are not. Herein, we present an immersion-deposition\napproach that enables the modification of mild steel (MiS) with diisopropylbenzimidazolium\nhydrogen carbonate (<sup><b>iPr</b></sup><b>NHC</b>·<b>H</b><sub><b>2</b></sub><b>CO</b><sub><b>3</b></sub>). The NHC-modified surface was characterized by X-ray photoelectron\nspectroscopy, angle-resolved X-ray photoelectron spectroscopy, atomic\nforce microscopy-based infrared spectroscopy, time-of-flight secondary\nion mass spectrometry, and matrix-assisted laser desorption/ionization\ntime-of-flight mass spectrometry. These experimental methods provide\nsupport for the functionalization of mild steel with <sup><b>iPr</b></sup><b>NHC</b> and for the reduction of surface oxide by\nthe carbene. Electrochemical analyses and salt immersion tests were\nalso performed and they showed that the NHC coating increases the\ncorrosion resistance of MiS. This study demonstrates that immersion\ndeposition is a viable method for the modification of mild steel surfaces\nwith N-heterocyclic carbenes and shows the potential for mitigating\ncorrosion.