Au₁₃: CO Adsorbs, Nanoparticle Responds

Nanoparticle properties are strongly correlated with their morphologies, such as shape and size. By combining density functional theory calculations with ab initio molecular dynamics simulations, we investigated the CO adsorption behavior on Au₁₃ nanoparticles of I_h, O_h, and planar symmetries. Our results revealed a shape-specific adsorption response of the nanoparticles. Contrary to the behavior in bulk, we observe a symmetry-dependent d-band center shift on the nanoparticles with CO coverage, which affects the overall electronic stability of the nanoparticles. As a result, we observe 2D to 3D (planar to I_h) transition at high CO coverage. Because of the interactions with the adsorbed CO molecules, the 3D nanoparticles can accommodate more charge in their core than the 2D. All of these effects result in observing an unconventional, stronger CO adsorption on I_h Au₁₃ nanoparticles that expose higher surface coordination number (CN = 6) than the peripheral atoms of the planar Au₁₃ (peripheral CN = 3.4). This work highlights the shape effect on the adsorption behavior of small-sized Au nanoparticles (∼1 nm diameter)