Plasmon-Mediated Hydrogen Dissociation with Symmetry Tunability

Theatomic-scale mechanism of plasmon-mediated H-2 dissociationon gold nanoclusters is investigated using time-dependent densityfunctional theory. The position relationship between the nanoclusterand H-2 has a strong influence on the reaction rate. Whenthe hydrogen molecule is located in the interstitial center of theplasmonic dimer, the hot spot here has a great field enhancement,which can promote dissociation effectively. The change in the molecularposition results in symmetry breaking, and the molecular dissociationis inhibited. For the asymmetric structure, direct charge transferfrom the gold cluster to the antibonding state of the hydrogen moleculeby plasmon decay makes a prominent contribution to the reaction. Theresults provide deep insights into the influence of structural symmetryon plasmon-assisted photocatalysis in the quantum regime.