Hole Transfer Channel of Ferrihydrite Designed between Ti-Fe2O3 and CoPi as an Efficient and Durable Photoanode

A high-efficient oxygen evolution cocatalyst decorated on alpha-Fe2O3 has been considered as one of the most prospective approaches to accelerate the charge transport at the interface between photoanode and electrolyte. However, efficient charge transport from the semiconductor to the surface of the cocatalyst is still a challenge in fabricating semiconductor electrodes integrated with cocatalysts. Here, we elaborately introduce ferrihydrite (Fh) as a hole transfer channel between Ti doped alpha-Fe2O3 (Ti-Fe2O3) and cobalt phosphate (CoPi), which exhibits a superior photocurrent density of 3.0 mA/cm(2) at 1.23 V-RHE and 100 mV negative shift of the onset potential in contrast to CoPi/Ti-Fe2O3. The outstanding photoelectrochemistry performance is not only ascribed to the accelerated charge transfer from Ti-Fe2O3 to the surface of CoPi, but also beneficial from the fluent injection of photogenerated holes into the electrolyte, when Fh is introduced between Ti-Fe2O3 and CoPi. This work emphasizes the importance of introducing a hole transfer channel between semiconductor and cocatalyst in constructing outstanding photoanodes.