Methanol and ethanol are widely used as solvents, energy storage materials and raw materials for the manufacture of other chemicals, among which steam reforming of methanol and ethanol provides an effective method for hydrogen production. Therefore, understanding the hydrogen bond interaction between water and alcohol molecules on the solid surface is key, but small clusters of weakly interacting molecules are susceptible to perturbations, and imaging them in real space at the atomic scale remains a technical challenge. In this paper, the non-invasive imaging technology of qPlus atomic force microscopy, combined with density functional theory (DFT) and AFM simulation, can accurately identify methyl and ethyl alcohol molecules, and analyze the hydrogen bond network of water-alcohol mixture. We found that when water is involved, alcohol molecules will be transformed from tetramer and one-dimensional chain into double and three-ring clusters composed of five and six membered rings, and these clusters formed by water molecules bridge on the surface of Cu(111) and Cu(110). In addition, water-induced polycyclization of alcohols is also applicable to ethanol, and is expected to be widely used in hydrogen bonding systems containing hydrophilic and hydrophobic groups.

High resolution STM and AFM images of methanol-water mixture on Cu(110) surface. Overview of STM images and corresponding AFM images of methanol-water mixtures on Cu(110).

Article links：https://doi.org/10.1021/acs.jpcc.4c02039