Predicted Structures of the Active Sites Responsible for the Improved Reduction of Carbon Dioxide by Gold Nanoparticles

Abstract

Gold (Au) nanoparticles (NPs) are known experimentally to reduce carbon dioxide (CO 2 ) to carbon monoxide (CO), with far superior performance to Au foils. To obtain guidance in designing improved CO 2 catalysts, we want to understand the nature of the active sites on Au NPs. Here, we employed multiscale atomistic simulations to computationally synthesize and characterize a 10 nm thick Au NP on a carbon nanotube (CNT) support, and then we located active sites from quantum mechanics (QM) calculations on 269 randomly selected sites. The standard scaling relation is that the formation energy of *COOH (ΔE *COOH ) is proportional to the binding energy of *CO (E binding *CO ); therefore, decreasing ΔE *COOH to boost the CO 2 reduction reaction (CO 2 RR) causes an increase of E binding *CO that retards CO 2 RR. We show that the NPs have superior CO 2 RR because there are many sites at the twin boundaries that significantly break this scaling relation.

Recent Progress in the Theoretical Investigation of Electrocatalytic Reduction of CO2

“…The scientific research can be more comprehensive compared with the complicated solvation model, especially for the system-atical studies on some variable and high-throughput screening of a series of materials. These results qualitatively reproduced experimental observations that (211) surfaces required lower applied potentials than (111) and (100) Reproduced with permission. [32] They examined (111), (100), and (211) surfaces, and found enhanced intermediate stabilization and lower onset potentials for CH 4 evolution on (211) surfaces, whereas the close-packed surfaces (111) and (100) are less active.…”

“…[32] They examined (111), (100), and (211) surfaces, and found enhanced intermediate stabilization and lower onset potentials for CH 4 evolution on (211) surfaces, whereas the close-packed surfaces (111) and (100) are less active. The scientific research can be more comprehensive compared with the complicated solvation model, especially for the system-atical studies on some variable and high-throughput screening of a series of materials.…”

“…[82] As a result, for metals binding hydrogen weakly (such as Cu), CO 2 electroreduction suppressed HER; while if the binding was too strong, CO adsorption could actually enhance HER, in consistent with the follow-up experiments. [85] Liu et al located a series of CO reduction transition states on water-coated (111) and (211) facets of various metals. If the reduction goes via oxygen-bound species, the scaling relationship might be broken.…”

“…Thus, the supported metal nano-materials, including nanoparticles (NPs) and nanowires (NWs), with numerous unsaturated sites are sup-posed to be promising catalysts for CO 2 electroreduction. Lim et al showed that the edge area of graphene-supported Cu 55 cluster could indeed decrease overpotential compared to Cu (111) surface. [99,100] Theoretical calculations were wildly employed to help understand the performance of various structures, such as Au NP, [101,102] Au NW, [103] Ag NP, [104] Pd NP, [105,106] and AuCu alloy NP.…”

A Highly Active Star Decahedron Cu Nanocatalyst for Hydrocarbon Production at Low Overpotentials

“…[3][4][5]7,12,14,15] Since the study showing a linear correlation between grain boundary (GB) density and CO 2 RR performance by Li et al, [16] GBs have been explored as highly active catalytic sites for both CO 2 RR and carbon monoxide reduction, which promoted the production of CO and formic acid. [18] Hence it would be interesting to realize Cu nanostructures with high TB for CO 2 RR. [17] Cheng et al also reported a theoretical study showing that highly active twin boundaries (TBs) on the Au surface can be superior to GBs and other defects for CO 2 RR.…”