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

Abstract

Cubic-shape hematite (C-Fe _2 O _3 ) was facilely prepared by hydrothermal autoclave reaction of Fe ^3+ in the presence of 1,12-diaminododecane at 130 °C for 10 h. The surface of C-Fe _2 O _3 was decorated with nanosilvers through the sonochemical reduction of Ag precursor (0.1–0.4 ml of 1.0 wt.% AgNO _3 ), so-called C-Fe _2 O _3 @Ag. After then, the C-Fe _2 O _3 @Ag was plated with Au layer via galvanic-assisted reduction of Au precursor (0.04–0.14 ml of 1.0 wt.% HAuCl _4 ), so-called C-Fe _2 O _3 @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-Fe _2 O _3 @Ag (0.2 ml) exhibited the five-fold increase of photocatalytic activity to that of the pristine C-Fe _2 O _3 . Furthermore, Au-deposited C-Fe _2 O _3 @Ag (0.2 ml), i.e., C-Fe _2 O _3 @Ag-Au, exhibited the 200% increase of photocatalytic activity to that of the C-Fe _2 O _3 @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.

Keywords

• cubic-shape
• hematite
• plasmonic
• Au-Ag bimetal
• visible light