Reversible Photochromic Phenomenon of Plasmonic Metal/Semiconductor\nHeterostructures via Photoinduced Electron Storage

The\ntransfer and migration process of the photogenerated charge\ncarriers in plasmonic metal/semiconductor heterostructures not only\naffects their photocatalytic performance but also triggers some captivating\nphenomena. Here, a reversible photochromic behavior is observed on\nthe Au/CdS heterostructures when they are investigated as photocatalysts\nfor hydrogen production. The photochromism takes place upon excitation\nof the CdS component, in which the photogenerated holes are rapidly\nconsumed by ethanol, while the electrons are transferred and stored\non the Au cores, resulting in the blue shift of their localized surface\nplasmon resonance. The colloidal solution can restore its initial\ncolor after pumping with air, and the photochromic behavior can be\ncycled five times without obvious degradation. The finding represents\ngreat progress toward the photochromic mechanism of metal/semiconductor\nheterostructures and also reveals the importance of understanding\nthe dynamic process of the photogenerated charge carriers in these\nheterostructures.