Synthesis of novel Cu2O micro/nanostructural photocathode for solar water splitting

The hierarchical p-type Cu2O micro/nanostructural film on copper foil is successfully fabricated via a facile and cost-effective template route through transformation of lotus-like CuO/Cu(OH)2 nanosheet/nanowire structure for photoelectrochemical (PEC) hydrogen generation. Various size of Cu2O micro/nanostructure transfers from CuO nanosheets and Cu(OH)2 nanowires by means of thermally reducing the oxides from Cu2+ to Cu1+ at temperature of 500 °C under nitrogen atmosphere. Mott-Schottky plot shows the flat band potential of the hierarchical Cu2O film to be −0.17 V vs. Ag/AgCl and a hole concentration of 5.7 × 1019 cm−3. Direct band gap of 2.03 eV in Cu2O film is determined via incident photon-to-electron conversion efficiency measurement. Significantly, this Cu2O hierarchical photocathode exhibits remarkable photocurrent of −1.6 mA cm−2 at a potential of −0.6 V vs. Ag/AgCl, corresponding to the solar conversion efficiency of 1.97%. These results demonstrate the Cu2O micro/nanostructural film have great potential in solar hydrogen applications.