Influence of a Cu–zirconia interface structure on CO2 adsorption and activation

Abstract

CO adsorption and activation on a catalyst is a key elementary step for CO 2 conversion to various valuable products. In the present computational study, we screened different Cu-ZrO 2 interface structures and analysed the influence of the interface structure on CO 2 binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favours one position on both tetragonal and monoclinic ZrO 2 surfaces, where the bottom Cu atoms are placed close the lattice oxygens. CO 2 prefers a bent bidentate configuration at the interface and the molecule is clearly activated being negatively charged. Straining of the Cu nanorod influences CO 2 adsorption energy but does not change the preferred nanorod position on zirconia. Altogether, our results highlight that CO 2 adsorption and activation depend sensitively on the chemical composition and atomic structure of the interface used in the calculations. This structure sensitivity may potentially impact further catalytic steps and the overall computed reactivity profile.

Exploring CO2 Hydrogenation to Methanol at a CuZn--ZrO2 Interface via DFT Calculation

“…1 for the structures and denominations). The Cu-(m-ZrO 2 (111)) interface model was adopted from our previous study, 43 where the length of the nanorod is eight atoms and the thickness three atomic layers. A (111) plane is exposed towards the interface.…”

“…This unit cell size results in a minor compressive strain of −1.02 % for the Cu atoms along the direction of the nanorod. 43 For the Zn interface, the strain is −4.2 % and originates from the longer, 2.69 Å, Zn-Zn bulk distance. All three doped interfaces have a Zn atom at the most active reaction site so that they all measure the impact of Zn against the performance of the pure Cu interface.…”

“…Subsequent hydrogenation steps are then performed for the most stable CO 2 adsorption geometry, which is similar to the one for the Cu interface. 43 CO 2 binds to the CuZn-ZrO 2 interface in a conformation where the carbon atom resides on top of a Zn atom (C-Zn bond length 2.1 Å)…”

“…S6). Upon adsorption, CO 2 takes a bent shape, which resembles a carbonate anion 21,43 and indicates the activation of the molecule with a partial charge of 1.3 |e|. 43 The interaction of CO 2 with the CuZn-ZrO 2 interface leads to a local deformation of the rod such that the metal atom in contact with the C atom is pulled out from the (111) plane.…”

“…The Cu interface exhibits significantly weaker binding with an adsorption energy of −0.64 eV. 43 The difference can be rationalised by examining the energy penalty of deformation ∆E def , calculated using Eq. ( 1), which is +1.7 eV for the Cu interface and +1.1 eV for the Zn-dilute interface.…”