Highly efficient photoelectrochemical hydrogen generation using a quantum dot coupled hierarchical ZnO nanowires array.

A highly efficient photoelectrochemical cell was developed using a quantum dot semiconductor coupled hierarchical ZnO nanostructure for hydrogen generation. The hierarchical ZnO nanostructure consists of ZnO nanowire as a core and 2-dimensional ZnO nanosheets shelled on the ZnO nanowire surface. This multi-dimensional nanostructured photoanode was optimized with solution process conditions for efficient charge separation and transportation, and the visible light harvesting was effectively enhanced using the low bandgap semiconductor cadmium chacogenide quantum dots. Our hierarchical ZnO nanowire photoelectrode has greatly improved the saturated photocurrent density (17.5 mA/cm(2)) at 0.4 V vs. RHE under 1 sun illumination condition. In addition, we have modified the photoelectrode with IrO(x)·nH2O deposition to enhance the photostability, showing a noticeable improvement in steady generation of photocurrent under the light illumination condition.