Desorption of Oxygen from Cationic Niobium Oxide Clusters Revealed by Gas Phase Thermal Desorption Spectrometry and Density Functional Theory Calculations

Abstract

Thermal dissociation of cationic niobium oxide clusters (NbO) was investigated by gas phase thermal desorption spectrometry. The dominant species formed at 300 K were NbO (n = 2, 4, 6, ...; p = 0, 1, 2, ...) and NbO (n = 3, 5, ...; q = 0, 1, 2, ...). At higher temperatures, the more oxygen-rich clusters were observed to release O. However, the desorption of O from NbO was found to be insignificant in comparison with VO because Nb tends to have a +5 oxidation state exclusively, whereas V can have both +4 and +5 oxidation states. The propensity for the release of O atoms was manifested in the formation of NbO from NbO for odd values of n, whereas VO released O molecules instead. The energetics of the O and O release from the Nb and V oxide clusters, respectively, was consistent with the results of DFT calculations.

Gas-Phase Reactions of Carbon Dioxide with Copper Hydride Anions Cu2H2–: Temperature-Dependent Transformation

“…In the condensed-phase studies for CO 2 utilization, the temperature effect on the product selectivity has been readily explored . In the gas-phase studies, the high-temperature experiments have been rarely reported and the available examples typically explored are the reaction systems of metal oxide clusters. − Recently, the reaction of FeC 3 – anion with CH 4 at high temperatures (300–610 K) was reported and the production of C 2 H 2 via C–C coupling was identified . The reaction of CO 2 on liquid Al 100 + species that was preheated in the cluster source was reported by Jarrold and co-workers .…”

Density Functional Theory Calculations of Geometrical and Electronic Properties of Neutral and Charged Silicon Oxide Clusters

“…In most theoretical studies, the B3LYP functional and the 3‐21G, 6‐31G*, and 6‐31G** basis sets have been used . However, B3LYP, M06, and PBE functionals have also recently been widely used for metal oxide clusters calculations . In 2017, Byun et al .…”

Oxygen Release from Cationic Niobium–Vanadium Oxide Clusters, NbnVmOk+, Revealed by Gas Phase Thermal Desorption Spectrometry and Density Functional Theory Calculations

“…11 −10)] were synthesized in the gas phase. 19,20 The thermal desorption of oxygen from the near-stoichiometric (n:k = 2:5) clusters was investigated using mass spectrometry in combination with gas phase thermal desorption spectrometry (TDS). 19−22 For niobium oxide clusters and vanadium oxide clusters with even values of n, M n O (5/2)n+1 + (M = Nb, V; n = 2, 4, 6, ...), an O 2 molecule was released upon heating.…”

“…These experimental results can be explained by the tendency of Nb atoms to favor the +5 oxidation state, whereas V atoms can be in either the +4 or +5 states. 20 This raised questions regarding the release of oxygen from mixed clusters of vanadium and niobium oxides as to whether it is released as O atoms or molecules. In this context, it is also interesting to clarify if the oxidation state will continue to determine patterns of thermal dissociation.…”

“…In our previous studies, cationic niobium oxide clusters [Nb n O k + ( n = 2–10)] and vanadium oxide clusters [V n O k + ( n = 2–10)] were synthesized in the gas phase. , The thermal desorption of oxygen from the near-stoichiometric ( n : k = 2:5) clusters was investigated using mass spectrometry in combination with gas phase thermal desorption spectrometry (TDS). − For niobium oxide clusters and vanadium oxide clusters with even values of n , M n O (5/2) n +1 + (M = Nb, V; n = 2, 4, 6, ...), an O 2 molecule was released upon heating. The vanadium oxide clusters released O 2 readily at a lower temperature than the niobium oxide clusters, implying lower desorption energies of O 2 from the clusters.…”