Hydride-Containing Pt-doped Cu-rich Nanoclusters: Synthesis, Structure, and Electrocatalytic Hydrogen Evolution

A structurally precise hydride-containing Pt-doped Cu-rich nanocluster [PtH₂ Cu₁₄ {S₂ P(Oⁱ Pr)₂ }₆ (CCPh)₆ ] (1) has been synthesized. It consists of a bicapped icosahedral Cu₁₄ cage that encapsulates a linear PtH₂ unit. Upon the addition of two equivalents of CF₃ COOH to 1, two hydrido clusters are isolated. These clusters are [PtHCu₁₁ {S₂ P(Oⁱ Pr)₂ }₆ (CCPh)₄ ] (2), which is a vertex-missing Cu₁₁ cuboctahedron encaging a PtH moiety, and [PtH₂ Cu₁₁ {S₂ P(Oⁱ Pr)₂ }₆ (CCPh)₃ ] (3), a distorted 3,3,4,4,4-pentacapped trigonal prismatic Cu₁₁ cage enclosing a PtH₂ unit. The electronic structure of 2, analyzed by Density Functional Theory, is a 2e superatom. The electrocatalytic activities of 1-3 for hydrogen evolution reaction (HER) were compared. Notably, Cluster 2 exhibited an exceptionally excellent HER activity within metal nanoclusters, with an onset potential of -0.03 V (at 10 mA cm^-2 ), a Tafel slope of 39 mV dec^-1 , and consistent HER activity throughout 3000 cycles in 0.5 M H₂ SO₄ . Our study suggests that the accessible central Pt site plays a crucial role in the remarkable HER activity and may provide valuable insights for establishing correlations between catalyst structure and HER activity.