Preparation of Layered Double Hydroxide and its Graphene Composite Films as Electrodes for Photoelectrochemical Cells

Abstract

Visible-light responsive photoanodes for water splitting into hydrogen and oxygen were fabricated via NiTi-layered double hydroxide (NiTi-LDH, [Ni1-xTix(OH)2]2x+(An-)2x/n・mH2O]) and NiTi-LDH/graphene composite prepared by homogeneous precipitation methods. The NiTi-LDH and NiTi-LDH/graphene films were formed on transparent fluorine-doped tin oxide (FTO) glass substrates by electrophoretic deposition (EPD). The EPD films showed the pattern of hydrotalcite structure under x-ray diffraction, indicating that NiTi-LDH has been deposited on FTO by EPD without degradation. NiTi-LDH powder was obtained from formic acid intercalated LDH by homogeneous precipitation in formamide with hexamethylenetetramine, and NiTi-LDH/graphene composite was obtained from graphene and NiTi-LDH aqueous suspension with urea. The formed NiTi-LDH and NiTi-LDH/graphene composite films have different morphologies. Both NiTi-LDH and NiTi-LDH/graphene films prepared showed photovoltage of 15-55 mV under visible-light irradiation. Their photoelectrochemical properties were affected by the film morphology.