Synthesis and photoelectrochemical cell properties of vertically grown α-Fe₂O₃ nanorod arrays on a gold nanorod substrate

Photoelectrochemical cells prepared from highly ordered and vertically grown α-Fe₂O₃ nanorod arrays on a Au nanorod substrate showed about 8 mA cm^-2 photocurrent density under 1 sun condition without any hole scavenger. To the best of our knowledge, it is the highest value obtained from α-Fe₂O₃. The Au nanorod arrays were firstly grown inside the AAO nanotubes to provide a conductive surface, not only for the electrochemical deposition of the target material, but also to act as the current collector of a photoelectrochemical cell. Then, the Fe nanorods were electrodeposited on the gold nanorods and annealed in an O ₂ atmosphere to convert them into α-Fe₂O₃ nanorod arrays. The α-Fe₂O₃ nanorod arrays stood freely on the gold nanorod arrays after the removal of the AAO template. The photoelectrochemical properties of the α-Fe₂O₃ nanorod arrays as a photoanode were studied by evaluating their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5 100 mW cm^-2 illumination. Also, the dependence of the photocatalytic ability of the α-Fe₂O₃ nanorod arrays on their length was studied and the optimum rod length was determined.