Assisted deprotonation of formic acid on Cu(111) and self-assembly of 1D chains

Abstract

Formic acid (HCOOH) deprotonates on the open surfaces of Cu(110) and Cu(100) when exposed at 300 K. However, this does not occur on the close-packed surface of clean Cu(111). In this study, we show that the deprotonation of formic acid on atomically flat Cu(111) surfaces can be induced by pre-adsorbing polymeric formic acid clusters at low temperatures, and then annealing the system to break the acidic O–H bond of HCOOH adsorbed on the edges of the polymeric clusters. The thermal activation of HCOOH to bidentate formate was studied using a combination of infrared reflection absorption spectroscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Extended 1D formate structures self-assemble due to a templating effect introduced by the formation of long α-polymeric formic acid chains commensurate with the substrate.