Adsorption and reaction of 2-methylbenzimidazole molecules on a partially oxidized Cu(110) surface

Abstract

N-Heterocyclic carbenes (NHCs) have emerged as a promising candidate for functionalizing and modifying metal surfaces. Despite extensive research, the influence of oxides, which frequently occur on metal surfaces, on the adsorption behavior of NHCs has received limited attention at the nanometric scale. In this study, the adsorption configurations and reactions of 2-methylbenzimidazole (MBI) molecules on a CuO/Cu(110) surface were investigated using scanning tunneling microscopy and non-contact atomic force microscopy (nc-AFM). Following the deposition of MBI molecules, Cu islands were observed, and the molecules predominantly adsorbed in a flat-lying configuration. Comparative experiments conducted on a bare Cu(110) surface indicate that the dehydrogenation of MBI molecules due to the cleavage of N–H bonds leads to CuO reduction and the release of Cu adatoms, which subsequently aggregate into islands. Upon annealing at 378 K, molecules adsorbed at the CuO strips assume a tilted flat-lying configuration, suggesting the formation of coordination bonds between nitrogen and copper atoms. On the copper regions, molecules assemble into double-chains, adopting an upright configuration. High-resolution nc-AFM images reveal a similarity between molecules in the double-chains and those at step edges, implying that Cu atoms are extracted from terraces to form slots where molecules preferentially occupy.