Synthesis and Properties of Au Hydride

The generation of chemical species from gases, noble metals and light interacting with localized surface plasmons represents a new paradigm for achieving low energy sustainable reaction pathways. Here, we demonstrate that the dissociation reaction of H ₂ meditated by the decay of localized surface plasmons of gold nanoparticles leads to the generation of a new material as detected by a change in the optical properties of the gold nanostructures. The effective permittivity measured by in situ spectroscopic ellipsometry shows a blue-shift of 0.02 eV in the surface plasmon resonance, demonstrating the plausible formation of a metastable gold hydride layer on the surface of nanoparticles following the dissociation of H ₂ . The formation of this gold hydride through the interaction of gold with atomic H is supported by first-principles simulations. These calculations do not indicate a significant charge transfer upon hydrogenation of the (111) surface but rather large Friedel charge oscillations within the gold layer. Moreover, our blue-shift is produced by the formation of a hydride leading to changes in critical band gaps in the electronic structure. For a coverage of 11%, the calculated peak of the imaginary part of the ZZ-component of the dielectric tensor undergoes a blue shift of 28 nm from a hydrogen free peak at 574 nm.