Solvothermal Growth of Cu/Cu₂O/NiFe Layered Double Hydroxide for Hydrogen Evolution from UV-Visible-Light-Driven Water Splitting

The photocatalytic hydrogen production plays a key role as a potential process to generate an efficient energy. Because the demand of hydrogen energy is increasing in many chemical processes, the development of low cost photocatalyst has been gaining much attention in recent years. Layered double hydroxide is a two-dimensional layered clay that has been widely used as a photocatalyst but suffers from low transportation of the charge carriers. To suppress the limitation, herein, the Cu/Cu2O/NiFe-layered double hydroxide was synthesized by a facile solvothermal method. The aid of glycerol could be used to reduce Cu2+ and Fe3+ to Cu-0/Cu+ and Fe2+, resulting in the increase of absorption in the visible-light region. The glycerol concentration affected the formation of copper species. The Cu2CO3(OH)(2)/Cu2O was formed by using a 7.5 vol.% glycerol aqueous solution, then the Cu/Cu2O species formed when the glycerol concentration reached 30 vol.%. All copper species, i. e. CuO, Cu2CO3(OH)(2), Cu and Cu2O could act as co-catalysts and increased the photocatalytic activity of NiFe-layered double hydroxide, where the most active species was Cu/Cu2O. The Cu/Cu2O/NiFe-layered double hydroxide could generate hydrogen from water with the presence of methanol as a sacrificial reagent, with an apparent quantum yield of 0.53 % at 400 nm.