Quantum mechanical studies of full-shell noble metal nanoclusters in water
XL Xia and YZ Shao, INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, 118, e25709 (2018).
Water-metal interfaces are ubiquitous, but their underlying physicochemical principles remain elusive. In this work, we performed scalar-relativistic and dispersion-corrected first-principle calculations for full-shell noble metal nanoclusters in water for characterizing their electronic interactions. With increasing nanocluster (NC) size, the average bond lengths of Ag and Au NCs decrease due to their strong relative effects, while those of Pd and Pt NCs increase normally. The calculated Lowdin net atomic charges show that naked full-shell M-x (M is denoting Ag, Au, Pd, and Pt with x=13, 55, 147, respectively) nanoclusters have core-shell charge separations with positively charged core and negatively charged surface. Ag and Au NCs have higher charge separations with their well delocalized s-electrons as compared with Pd and Pt NCs. The charged surface noble metal atoms of nanoclusters gain a small amount of electrons from neighbor oxygen atoms of water. The electronic structure analysis manifests a mixing state of hybrid s-p-d orbitals of noble metal nanoclusters with O_p states of water, which gives rise to the electronic interactions of dative-bond character between noble metal nanoclusters and water. Such a kind of electronic interaction leads to charge transfer from neighbor oxygen atoms of water to surface noble metal atoms. These findings have an implication for those researches and applications in association with noble metal nanoclusters in liquid environments.
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