Engineering Dumbbell-Shaped Au Nanobipyramid/Ag-CeO2 Plasmonic Bimetal-Semiconductor Heterostructures for Nitroaromatic Reduction

Abstract

Precisely engineering the morphology of plasmonic metal–semiconductor heterostructures (PMSHs) is essential for fully utilizing the localized surface plasmon resonance (LSPR) function. However, most of the PMSHs mainly depend on the LSPR contribution of a single plasmonic metal, while the bimetal semiconductor heterostructures have been rarely reported. Herein, a series of dumbbell-shaped bimetal semiconductor heterostructures, based on Au nanobipyramids (AuNBPs, average length of 96 ± 3 nm, waist diameter of 29 ± 3 nm), lateral surfaces covered with rice-shaped Ag layers (thickness less than 5 nm), and a tip loaded with cap-shaped CeO2 (average size of 44 nm), were engineered. By simply tuning the dose of Ag+ and CTAC, we can precisely engineer the morphology of PMSHs from dumbbell-shaped monometal semiconductors (AuNBP–CeO2) to a core/shell/shell structure (AuNBP@Ag@CeO2) and to the dumbbell-shaped bimetal semiconductor AuNBP/Ag–CeO2. Notably, the AuNBP/Ag–CeO2 nanostructure exhibits higher activity in photocatalytic nitroreduction of 4-NP than AuNBP–CeO2. Mechanism analysis demonstrated that the bimetal semiconductor dumbbell-shaped AuNBP/Ag–CeO2 shows stronger electromagnetic field enhancement than the monometal semiconductor dumbbell-shaped AuNBP–CeO2, which promotes the generation of hot electrons more efficiently. This work offers an insight into precisely engineering plasmonic bimetallic semiconductor heterostructures for photocatalytic applications.