IR spectroscopic characterization of the co-adsorption of CO₂ and H₂ onto cationic Cu_n⁺ clusters

Abstract

To understand elementary reaction steps in the hydrogenation of CO2 over copper-based catalysts, we experimentally study the adsorption of CO2 and H2 onto cationic Cun+ (n = 4–7) clusters.

IR Spectroscopic Characterization of Methane Adsorption on Copper Clusters Cun+ (n = 2–4)

“…We have recently reported IR multiple photon dissociation (IRMPD) spectra of Cu n + ·Ar ( n = 3–10) and of the products resulting from the individual reactions of H 2 /D 2 and CO 2 , and their combination with Cu n + . − Here, we extend our work to reaction products with methane. Because Cu + binds CH 4 in η 2 coordination more strongly than Au + , it could be expected that Cu n + clusters may be more reactive toward CH 4 than Au n + clusters.…”

“…Geometries of Cu n + –CH 4 were optimized using the Gaussian 16 package with the Perdew–Burke–Ernzerhof (PBE) functional with a triple-ζ basis set with two polarization functions (Def2-TZVPP). , This functional was chosen because it has successfully explained our previous work on copper cluster cations interacting with Ar, H 2 , and CO 2 . − A test calculation on the Cu 2 + –CH 4 system showed that PBE and B3LYP yield very similar predicted IR spectra. Trial geometries of the Cu n + –CH 4 complexes were constructed by taking the earlier determined structures of cationic Cu clusters and complexing them with CH 4 at several adsorption sites and configurations of CH 4 , including structures where CH 4 was dehydrogenated to form hydrido-methyl complexes.…”

Quantum chemical and microkinetic study of H2 dissociation on Cu4 cluster in the gas phase

“…Different types of initial cluster and bonding motifs of the H2 were investigated previously, where we performed optimization on different initial cluster geometries to locate the lowest energy bare Cu4 and Cu4 + , and different binding motifs were systematically generated using our in-house code, what has also been applied e.g in ref. [34]. The previously optimized structures with TPSSh/def2-TZVP + D3 were reoptimized using the PBE+D3/cc-pVTZ-PP (involving also relativistic effective core potential) , while single point energies were computed at the CCSD(T)/cc-pVTZ-PP, after a systematic benchmark up to CCSD(T)/def2-QZVPPD.…”

“…In our previous work we investigated differently charged copper clusters reactions with CO2 and CO2 + H2, and we could not exclude or confirm the H2 dissociation due to the absence of characterization methods. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] To analyze elementary steps in different conditions a microkinetic model is needed. Master equation is a well-used model for combustion reaction [35], and can form a bridge between calculations and experiments, due to their validity on different pressure ranges.…”

Zooming in on the initial steps of catalytic NO reduction using metal clusters

“…This technique has been successfully used to infer the structure of cluster-molecule complexes. [67][68][69][70][71][72] For the thermal stability, we used thermal desorption spectrometry (TDS) to analyze until what temperatures cluster-NO complexes survive, from which the binding energies can be inferred.…”