DFT and RAIRS Investigations of Methanol on Cu(110) and on Oxygen-Modified Cu(110)

Abstract

The adsorption and subsequent reaction of methanol on Cu(110) and on the oxygen stripe phase on Cu(110) was investigated using reflection absorption infrared spectroscopy (RAIRS), temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. It was shown that during high methanol exposures water can coadsorb and it is incorporated into the methanol rows formed in the chemisorbed layer. The RAIR spectra of adsorbed methanol are very similar with and without coadsorbed oxygen. This is due to the fact that the ν(CO) vibration is at the same frequency for both methanol and methoxy adsorbed in the more stable short-bridge site. However, methoxy adsorbed in the long-bridge site shows the ν(CO) vibration at lower wavenumbers and is found with increasing surface temperature. With coadsorbed oxygen the reaction products are formaldehyde, H 2 , and CO 2 . DFT and RAIRS results suggest that the intermediate leading to CO 2 is an η 2 -formaldehyde and OH species on the surface, rather than formate.

Insight into the influence of liquid paraffin for methanol synthesis on Cu(110) surface using continuum and atomistic models

“…Hence, HCO formation is more preferred. In vacuum, as shown in Table 1, the adsorption energy of HCO is −1.71 eV which is in agreement with previous work [64]. The adsorption energy of COH is −2.67 eV.…”

Adsorption of intact methanol on Ru(0001)

“…Also, it has a high technological relevance in applications such as the direct methanol fuel cell, where Ru/Pt alloys are used as catalysts for dehydration of methanol. 2,3 In the past, the adsorption and thermal evolution of methanol has been studied experimentally as well as theoretically on numerous catalyst surfaces, such as Ru, [4][5][6][7][8] Cu, [9][10][11][12][13] Rh, 8,14 and Pt. [15][16][17][18] Especially, there exist ample theoretical works concerning the adsorption and dissociation pathways of methanol on different metal surfaces.…”

“…[15][16][17][18] Especially, there exist ample theoretical works concerning the adsorption and dissociation pathways of methanol on different metal surfaces. 10,11,13,17,18 Specifically, binding energies and geometries of reaction intermediates, as well as energetic activation barriers of the decomposition steps, have been calculated using density functional theory ͑DFT͒.…”

“…9͒ as well as on Pt͑111͒, 15,16 methanol adsorbs molecularly at low temperatures without dissociation. Annealing to T Ͼ 140 K desorbs methanol entirely from Cu͑111͒; on Pt͑111͒ chemisorbed methanol decomposes to form CO and H at 230 K. 15 Referring to DFT calculations 11,13,17,18 on Cu͑111͒ as well as on Pt͑111͒, methanol is bonded atop through the oxygen atom. On Cu͑111͒ Greeley and Mavrikakis 11 found that the hydroxyl group of methanol is oriented close to parallel to the surface plane.…”

Quantitative adsorbate structure determination under catalytic reaction conditions

“…[18,19,20,21]) and direct measurements of the reaction turnover frequency [22], while electronic and vibrational spectroscopies (e.g. [19,22,23,24]) provided direct identification of the surface reaction intermediates. The general consensus is that the key molecular surface intermediate is the methoxy species, which produces the desired products of formaldehyde (CH 2 O) and hydrogen after further reaction.…”