Theoretical Analysis of Catalytic Activity of Metal Surfaces on Reaction of Hypophosphite Ion

Abstract

To elucidate the mechanism of catalytic activity of metal surfaces on the reaction of hypophosphite ions, which act as a reducing agent for electroless deposition, molecular orbital interactions between hypophosphite ions and metal surfaces were analyzed using density functional theory. Pd (111) and Cu (111) were chosen as the surfaces with high and low catalytic activity, respectively. The electronic states of adsorption systems were analyzed using the Mülliken population analysis. The position of the d-band plays a key role in determining the catalytic activity on P-H bond cleavage of hypophosphite. The Pd surface has a d-band near the Fermi level and contains a vacancy; this enables the donation and back-donation effect to occur on the adsorbed hypophosphite and promotes P-H bond cleavage. On the other hand, the Cu surface has a d-band in the deep energy area and contains no vacancy; the donation and back-donation effect is not induced and P-H bond cleavage is not promoted. This difference in the degree of promotion of P-H cleavage is responsible for the difference in the catalytic activity on P-H cleavage and dehydrogenation of hypophosphite ions, which in turn explains the difference in the catalytic activity during the entire hypophosphite oxidation process.

Theoretical Analysis of Adsorption Structure of Hydrated Hypophosphite Ion on Pd (111) Surface

“…Although it is much smaller, such a model is known to provide sufficient results for analysis of adsorption behavior. 22,23 The effective core potential proposed by Hay and Wadt was used to represent the Ar core in Pd. 24 …”

Electrochemical Processes for the Fabrication of Functional Micro–nano Structures and Devices: Mechanistic Understanding and Process Development

“…The dehydrogenation step has also been demonstrated to be significant in case of other reductants such as dimethylamine borane (DMAB) and aldehydes; [11][12][13] thus, for elucidating its origin, further investigation on the interaction of the orbitals for hypophosphite ion and metal surfaces was conducted. 19,20 Figure 5 schematically shows the results obtained for the case with Pd and Cu surfaces. 19 For the adsorption on Pd, the s-orbital of H interacted with d-and p-orbitals, whereas the s-orbital of P interacted with the p-orbital of O [ Fig.…”