Structures and CO-Adsorption Reactivities of Nickel Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry

Abstract

Structures and CO-adsorption reactivities of nickel oxide cluster cations were investigated by ion mobility mass spectrometry. The series of Ni n O n−2 + , Ni n O n−1 + and Ni n O n + cluster cations were predominantly observed in a mass spectrum at high ion-injection energy into an ion-drift cell. From the arrival time distributions of Ni n O n + and Ni n O n−1 + in the ion mobility spectrometry, structural transition from two-dimensional (2D) ring to three-dimensional (3D) compact structures was found at n = 5. In addition, 2D and 3D structural isomers were found to coexist for Ni 5 O 5 + , Ni 6 O 5 + and Ni 7 O 6 + . By adding CO gas to buffer gas in the ion-drift cell, Ni 4 O 3 + and Ni 5 O 4 + cluster cations were found to be more reactive for the CO adsorption reactions than Ni 4 O 4 + and Ni 5 O 5 +. Under the pseudo-first-order approximation, rate constants for CO-adsorption were determined to be (8.4 ± 0.7) × 10 −11 cm 3 molecule −1 s −1 for Ni 4 O 3 + and (9.6 ± 0.8) × 10 −11 cm 3 molecule −1 s −1 for Ni 5 O 4 + . These rate constants are 2 orders of magnitude faster than those for Ni 4 O 4 + and Ni 5 O 5 + , which have reported previously. These differences of rate constants can be originated in the structures of the nickel oxide cluster ions.

Tuning the Magnetic Moment of Small Late 3d-Transition-Metal Oxide Clusters by Selectively Mixing the Transition-Metal Constituents

“…In this atomic configuration all metal–metal bonds are mediated by oxygen. This trend was already discussed in our previous works for the pure Fe, Co and Ni oxidized clusters [ 39 , 40 , 41 ], and it has been also discussed by other groups for other systems [ 33 , 51 ] in this small size range. We now demonstrate that these ring-like structures are preserved in the TM oxidized nanoalloys, except for Fe Ni O , for which a tetrahedral structure is obtained, as stated above.…”

Stable Compositions and Structures of Copper Oxide Cluster Cations CunOm+ (n = 2–8) Studied by Ion Mobility Mass Spectrometry

“…This stability trend is somewhat different from the IMS results of the other oxide cluster ions of 3d transition metals, Fe, Co, Ni, and Zn, reported previously by the authors’ group. 28−31 For example, stable structures of M n O n + , with M = Fe, Ni, Co, and Zn, were predicted as either ring or cubic for n = 4 and 5. However, the most stable structures for Cu 4 O 4 + and Cu 5 O 5 + were found to be 3D structures containing an O–O bond, which were also previously obtained theoretically by another group.…”

Structural and electronic properties of transition metal oxide clusters and their applications

“…In this atomic configuration all metal-metal bonds are mediated by oxygen. This trend was already discussed in previous chapters for the pure N i (chapter 3 (52)) and F e (chapter 4) clusters, and in our previous work of Co( 51) clusters, and it has been also discussed by other groups for other systems (83,107). We now see that these ring-like structures are preserved in the TM oxide nanoalloys at least for the 3d elements here considered.…”