Realization of Tunable Localized Surface Plasmon Resonance of Cu@Cu₂O Core–Shell Nanoparticles by the Pulse Laser Deposition Method

Cu@Cu₂O core–shell nanoparticles (NPs) not only possess a stabilized structure but also exhibit better photocatalytic performance as compared to pure Cu₂O. Therefore, preparation of Cu@Cu₂O core–shell NPs is key toward efficient photocatalysis applications. In this paper, the fabrication of Cu@Cu₂O core–shell NPs on single-crystal MgO(100) substrates has been studied systematically by pulse laser deposition. Scanning electron microscopy (SEM) images show that the average diameter of NPs is enlarged from 89.9 to 150.3 nm with the increasing of oxygen pressure. Transmission electron microscopy (TEM) images indicate that the NPs have elongated hexagons and a core–shell structure with a shell thickness of about 10 nm. UV–vis absorption spectra show that the position of the localized surface plasmon resonance (LSPR) peaks shifts from 648 to 858 nm and the full width at half-maximum (fwhm) of the LSPR peaks broadens from 226.7 to 436.5 nm with increasing average diameter of NPs. According to the analysis, the red shift of the LSPR peaks is caused by enlargement of the core diameter; higher fwhm is a result of broadened particle size distribution and the elongated morphology of NPs. Therefore, the width and range of LSPR peaks of the absorption spectrum can be tuned using this method, which is beneficial for enhancing the light absorption and improving the photocatalytic efficiency of Cu@Cu₂O core–shell NPs.