Ultrathin nanoporous metal–semiconductor heterojunction photoanodes for visible light hydrogen evolution

Plasmonic metal–semiconductor nano-heterojunctions (NHJs), with their superior photocatalytic performance, provide opportunities for the efficient utilization of solar energy. However, scientific significance and technical challenges remain in the development of suitable metal–semiconductor NHJ photoelectrodes for new generation flexible optoelectronic devices, which often require complex processing. Herein, we report integrated three-dimensional (3D) NHJ photoelectrodes by conformally coating cadmium sulfide (CdS) nanolayers onto ultrathin nanoporous gold (NPG) films via a facile electrodeposition method. Localized surface plasmon resonance (LSPR) of NPG enhances the electron–hole pair generation and separation. Moreover, the direct contact interface and high conductive framework structure of the NHJs boosts the photogenerated carrier separation and transport. Hence, the NHJs exhibit evidently enhanced photocurrent density and hydrogen evolution rate relative to CdS deposited on either gold (Au) foil or fluorine-doped tin oxide (FTO) at 0 V vs. SCE (saturated calomel electrode) under visible-light irradiation. Moreover, they demonstrate a surprisingly stable photoelectrochemical hydrogen evolution (PEC-HE) activity over 104 s of continuous irradiation.