New insights into the kinetics of formic acid decomposition on copper surfaces

Abstract

Abstract We use both time-resolved and static high resolution electron energy loss spectroscopies (EELS) to follow the chemisorption and subsequent decompostion of formic acid (HCOOH) on a Cu(1100) surface. Two stable forms are identified: one, existent at elevated temperatures, is a symmetrically bonded formate species (HCOO) oriented normal to the surface whereas the second, a low temperature high coverage structure, is canted. We believe this latter species to be a mixed array of hydrogen bonded formate and formic acid molecules. The observed tilting is not reversible at constant coverage, but can be driven by dosing the sample with formic acid while cooling. The implications of our results with respect to the catalytic dehydrogenation of formic acid on copper at high surface coverage are discussed.