Cubic-shape hematite decorated with plasmonic Ag-Au bimetals for enhanced photocatalysis under visible light irradiation

Cubic-shape hematite (C-Fe₂O₃) was facilely prepared by hydrothermal autoclave reaction of Fe³⁺ in the presence of 1,12-diaminododecane at 130 °C for 10 h. The surface of C-Fe₂O₃ was decorated with nanosilvers through the sonochemical reduction of Ag precursor (0.1–0.4 ml of 1.0 wt.% AgNO₃), so-called C-Fe₂O₃@Ag. After then, the C-Fe₂O₃@Ag was plated with Au layer via galvanic-assisted reduction of Au precursor (0.04–0.14 ml of 1.0 wt.% HAuCl₄), so-called C-Fe₂O₃@Ag-Au. Scanning electron microscopy demonstrated the formation of cubic-shape hematite deposited with plasmonic nanometals. X-ray photoelectron spectroscopy analysis confirmed the existence of Ag and Au crystals. Photocatalytic performance of the hematite samples was estimated towards the degradation of methylene blue (MB) under visible light. The C-Fe₂O₃@Ag (0.2 ml) exhibited the five-fold increase of photocatalytic activity to that of the pristine C-Fe₂O₃. Furthermore, Au-deposited C-Fe₂O₃@Ag (0.2 ml), i.e., C-Fe₂O₃@Ag-Au, exhibited the 200% increase of photocatalytic activity to that of the C-Fe₂O₃@Ag (0.2 ml), owing to the plasmonic coupling effect on the extended visible light absorbance and enhanced separation efficiency of electron-hole pairs on the hematite surface. (paper)