Design of Copper‐Based Bimetallic Nanoparticles for Carbon Dioxide Adsorption and Activation

Abstract

Cu-based nanoparticles (NPs) are promising candidates for the catalytic hydrogenation of CO to useful chemicals because of their low cost. However, CO adsorption and activation on Cu is not feasible. In this work we demonstrate a computational framework that identifies Cu-based bimetallic NPs able to adsorb and activate CO based on DFT calculations. We screen a series of heteroatoms on Cu-based NPs based on their preference to occupy a surface site on the NP and to adsorb and activate CO . We revealed two descriptors for CO adsorption on the bimetallic NPs, the heteroatom (i) local d-band center and (ii) electropositivity, which both drive an effective charge transfer from the NP to CO . We identified the CuZr bimetallic NP as a candidate nanostructure for CO adsorption and showed that although the Zr sites can be oxidized because of their high oxophilicity, they are still able to adsorb and activate CO strongly. Importantly, our computational results are verified by targeted synthesis, characterization, and CO adsorption experiments that demonstrate that i) Zr segregates on the surface of Cu, ii) Zr is oxidized to form a bimetallic mixed CuZr oxide catalyst, which iii) can strongly adsorb CO , whereas Cu NPs cannot. Overall our work highlights the importance of the generation of binding sites on a NP surface based on (catalyst) stability and electronic structure properties, which can lead to the design of more effective CO reduction catalysts.

Mechanistic and multiscale aspects of thermo-catalytic CO2conversion to C1products

“…On metallic surfaces, CO 2 activation usually consists of electronic charge transfer from the metal to CO 2 . [108][109][110] On metal oxides, on the other hand, the adsorption exploits the amphoteric nature of CO 2 , which has a partial positive charge on the C atom (+0.37 e from Mulliken's population analysis) and negative charges on the two O atoms (−0.18 e). 40 During the adsorption, the electron-deficient C atom and the more electron-rich O atoms can be attacked by either electron-rich or electron-deficient active sites, respectively.…”

“…109 Moreover, they showed that Zr sites can be oxidized because of their high oxophilicity; however, they are still able to adsorb and activate CO 2 easily. 110 Dixit et al 111 The adsorption configuration of CO* 2 changes with the structure and composition of the catalyst surface. 99,[108][109][110][111][112][113][114] Usually, the C atom and one O atom of CO* 2 bind to one or two metal atoms [108][109][110]112 (on the "top" or "bridge" adsorption sites).…”

“…Zhao et al 311 showed that the HCOO* path is kinetically unfavorable compared to the COOH* route, especially in the presence of water. The isotope labeling experiment by Chinchen et al 313 (110). They produced a theoretical volcano plot illustrating a clear relationship between the number of reduced surface In layers and the catalytic activity of In 2 O 3 (111).…”

“…110 Dixit et al 111 The adsorption configuration of CO* 2 changes with the structure and composition of the catalyst surface. 99,[108][109][110][111][112][113][114] Usually, the C atom and one O atom of CO* 2 bind to one or two metal atoms [108][109][110]112 (on the "top" or "bridge" adsorption sites). The other O atom of CO* 2 may interact with the surface.…”

“…Zhang et al 114 investigated the RWGS redox mechanism on Ni (111) and Ni (311), showing that the stepped (311) surface has higher catalytic activity than the flat (111) surface. Lin et al 155 investigated redox and carboxyl mechanisms on Ni (110) in the presence of a high density of subsurface hydrogen, showing that subsurface H atoms can play an important role in RWGS, by both lowering the energy barriers of the kinetic mechanism and participating actively in the hydrogenation elementary steps. They also concluded that, in their system, the redox mechanism is the most favorable RWGS pathway.…”