Fig. 1.

Characterization of plasmonic photocatalysts. a TEM image of the pristine Al NCs with nominal size before and b after growth of Cu₂O shell around Al core. The scale bars in a and b are 50 nm. c HRTEM image of Al/Al₂O₃/Cu₂O showing the Cu₂O layer is highly polycrystalline. The scale bar is 5 nm. d High-angle annular dark field scanning transmission electron micrograph (HAADF-STEM) of the Al@Cu₂O particles in low magnification and higher resolution (inset) indicating different Z-contrast for the core and the shell materials. The scale bars for low-resolution and inset images are 400, and 50 nm, respectively. e–h Energy-dispersive X-ray (EDX) mapping showing the distribution of Al e, Cu f and O g, and their overlay h