Adsorption behavior of formate (HCOO-) on Ni(1 1 0) surface has been investigated using a scanning tunneling microscope (STM) at cryogenic temperature. Formic acid (HCOOH) is found to dissociatively adsorb onto Ni(1 1 0) to produce formate at 50 K. Atomically resolved STM images revealed that formates can occupy either short-bridged (S-formate) or long-bridged (L-formate) sites at 50 K. At low surface coverages, formates are isolated and disordered when dosed at 50 K. Annealing of the Ni(1 1 0) surface to 120 K induces site conversion of L-formate to S-formate, indicating L-formate is a metastable state formed only at low temperature. Furthermore, L- and S-formates assemble to form dimers, trimers and short chains through thermal diffusion. This characteristic development of the formate chain is caused by anisotropic lateral interaction between neighboring formate molecules.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry