Cu2O Photocathode with Faster Charge Transfer by Fully Reacted Cu Seed Layer to Enhance Performance of Hydrogen Evolution in Solar Water Splitting Applications

In this work, we study the effect of Cu2O film obtained from a fully reacted Cu seed layer as a photoelectrode in photoelectrochemical cells. The full reaction of the Cu layer shows an enhanced photocurrent density and improved efficiency in hydrogen evolution. The photocurrent density of textured Cu2O (0.58 mA cm(-2) at 0 V vs. RHE), without an unreacted Cu layer is two times higher than films containing an unreacted Cu layer (0.29 mA cm(-2) at 0 V vs. RHE), under AM 1.5 illumination (100 mW cm(-2)). The thickness of the unreacted Cu layer influences significantly the charge transfer process at the interface between the Cu2O and electrolyte. The enhanced photoelectrochemical performance of textured Cu2O is attributed to the reduced charge recombination resulting from a longer carrier lifetime in the Cu2O layer. Experimentally we confirmed that the unreacted Cu layer inhibits the photoelectrochemical performance of Cu2O-based photocathodes. The elimination of the unreacted Cu layer leads to higher photocurrent density.