Topotactic cation exchange induced non-epitaxial atomic-organized interface in plasmonic metal-semiconductor hetero-films for efficient photoelectrochemical hydrogen evolution

Plasmonic metal-semiconductor hetero-structures exhibit synergetic coupling of plasmon and exciton, and therefore are promising in enhancing solar energy conversion. A well-ordered metal-semiconductor interface is of critical importance to prevent photocarriers recombination and amplify this coupling effect. Here, by a topotactic cation exchange strategy, we realized the synthesis of a centimeter-scale Au-CdS hetero-film with an atomic-organized interface. The obtained CdS films possess a hexagonal lattice, in contrast to the cubic structure that epitaxial grown on the polycrystalline Au substrate. First-principal calculations reveal CdS of hexagonal structure is energetically preferred in nature, indicating the growth of CdS film by topotactic cation exchange strategy is independent of the polycrystalline Au substrate. Under AM 1.5 G illumination, their photoelectrochemical hydrogen evolution activity is nearly 3.0 times higher than epitaxial grown hetero-film. Our work opens up the opportunity for synthesizing metal-semiconductor hetero-films with atomic-organized interfaces, paving the way for solar-to-fuel applications.