Plasmon-driven water splitting enhancement on plasmonic metal-insulator-semiconductor hetero-nanostructures: unraveling the crucial role of interfacial engineering.

Understanding and controlling the charge transfer behavior across the interface/junction in hybrid nanostructures is essential for various plasmon-enhanced catalytic reactions. The rational design of plasmonic nanostructures offers a unique capability for eliminating the daunting complexity of the electronic effect induced by interfacial interactions and maximizing the conversion efficiency of solar energy into chemical energy by surface coupling. Herein, we tactfully construct a new type of plasmon-driven photoanode based on plasmonic metal-insulator-semiconductor (PMIS) hetero-nanostructures (Au@SiO2 NP-decorated α-Fe2 O3 nanorod array), by using Fe2 O3 nanoarrays as model semiconductor structures and Au@SiO2 NPs as photosensitizers, for optimizing the photoelectrochemical (PEC) water splitting performance. The thin insulating layer (SiO2 ) of the hetero-nanostructure has been found to play a crucial role in significantly enhancing the plasmon-driven water splitting performance via eliminating the negative effect of surface states (resulting in Fermi level pinning and recombination) at the metal-semiconductor interface, suppressing the recombination of current carriers, as well as maximizing the metal-semiconductor barrier height. This study provides new insight into a novel plasmonic nanocatalyst design by rational interface engineering and will be of benefit for a better understanding of manipulating the interfacial electronic properties between plasmonic nanocrystals and semiconductors for catalytic applications.