Synthesis and characterizations of Cu2O/Ni(OH)2 nanocomposite having a double co-catalyst for photoelectrochemical hydrogen production

Cu2O/Ni(OH)(2) nanocomposites have been evaluated for use as a photocathode in hydrogen production cell. The Cu2O/Ni(OH)(2) nanocomposites were synthesized using a facile two-step solution method and green route method at room temperature. Cu2O spheres were first prepared, followed by the growth of Ni(OH)(2) on the spheres. Cu2O/Ni(OH)(2) nanocomposites having different percentages of Ni(OH)(2) were made. The released Ni from Ni(OH)(2) acts as co-catalysts assisting electron transfer and hence suppressing electron-hole recombination. For comparison, both the Cu2O spheres and Cu2O/Ni(OH)(2) nanocomposites were characterized and examined as a photocathode in photoelectrochemical cell for hydrogen production. The performance of the photocathode has been discussed in terms of light harvesting efficiency (LHE), external quantum efficiency (EQE), charge collection efficiency (CCE), and photoconversion efficiency (PCE). The LHE and EQE of the Cu2O/Ni(OH)(2) nanocomposite is better than that of the Cu2O spheres. We show that for the Cu2O spheres, PCE increase linearly with the CCE, while for the Cu2O/Ni(OH)(2) nanocomposites, the PCE increase and then levels off with the CCE. Furthermore, we have demonstrated the synergistic effect of coupling Cu2O/CuO with double co-catalyst Ni (OH)(2)/Ni, which greatly enhances the electron transfer and effectively reduce the hole-electron recombination. As a result, the PCE of the Cu2O/Ni(OH)(2) nanocomposite was found to be twice that of the Cu2O spheres. Furthermore, the highest hydrogen production rate of the Cu2O/Ni(OH)(2) is more than 15 times that of the Cu2O.