Density functional cluster model study of bonding and coordination modes of CO2 on Pd(111)

A Computational Study of Direct CO2 Hydrogenation to Methanol on Pd Catalysts

“…The undistorted CO2 is most stable with a C-Pd bond distance, d(C-Pd), of 3.454 Å, which agrees with the physisorbed species observed by Habas et al21 Eads(CO2) is strongest on the closepacked (111) surface, and is found to relate linearly with the number of Pd atoms that neighbour the surface adsorption site; when Eads(CO2) is plotted as a function of surface atom coordination number, which are 9, 8, and 7 for the Pd (111), (100), and (110) surfaces, respectively, a linear fit returns R 2 = 0.998.…”

“…20 In contrast, Zhang et al recently calculated the CO2 chemisorption on Pd (111) to be endothermic (0.06 eV) using the PBE density functional, in agreement with Habas et al, who reported the adsorption energy of CO2 to be 0.22 eV above the dissociation limit using DFT with the B3LYP density functional. 21 Liu et al have also shown that, when using the PBE density functional, the inclusion of the DFT-D2 correction dramatically changes the adsorption energy of chemisorbed species on the Pd (111) surface, from 0.30 eV to -0.18 eV. 16 Although there is no consensus on the matter of CO2 chemisorption endo-or exothermicity on Pd surfaces, the reported values are generally small, which agrees with the experimental reports of weak interaction between CO2 and Pd surfaces.…”

Theoretical study of CO2 hydrogenation to methanol on isolated small Pd clusters

“…Meanwhile, due to its strong interaction with H 2 molecule, the Pd island only acts as a site for dissociating H 2 molecule and providing the dissociated H atoms to the oxide surface or to the Pd-oxide interface. The Pd island site itself cannot act as a CO 2 hydrogenation center [21,22] which might be caused by its poor ability to adsorb CO 2 molecule properly [11,[23][24][25][26][27][28][29][30] . If the Pd site can also be utilized as an additional CO 2 hydrogenation center, then the activity of Pd/Oxide catalyst towards CO 2 hydrogenation reaction might be improved significantly.…”

Methanol synthesis from CO2 hydrogenation over a Pd4/In2O3 model catalyst: A combined DFT and kinetic study

“…These simplified model systems capture key features of the metalsupport interaction and provide interfacial sites as active sites for the catalytic transformation whereas quantitative agreement with the experimental system is generally not anticipated. Since CO 2 generally physisorbs on metallic Pd [50][51][52], the hydrogenation of CO 2 likely utilizes hydrogen adatoms generated on Pd and proceeds at the interface of the metal particle and the support. Herein, a Pd 4 cluster supported on In 2 O 3 (Pd 4 /In 2 O 3 ) was designed as a model catalyst to elucidate the mechanism of methanol synthesis from CO 2 hydrogenation using a combination of density functional theory calculation and microkinetic study.…”