Synthesis of Host-Guest Hematite Photoelectrodes for Solar Water Splitting

Hematite (alpha-Fe2O3) is a promising semiconductor for photoelectrochemical (PEC) water splitting, due to its abundance, low-cost and excellent stability. However, the efficiency of alpha-Fe2O3 photoelectrodes has been limited by its low hole mobility and fast electron-hole recombination. Host-guest architectures have emerged as a suitable design, which involves the use of a nanostructured collector for high solar absorption while maintaining an ultrathin absorber layer for better charge transport. In this study, a thin mesoporous SiO2 host template coated with a conductive thin layer of TiO2 was optimized to support the alpha-Fe2O3 film. The alpha-Fe2O3 thin layer was deposited by spray pyrolysis and then coated with a FeNiOOH co-catalyst. A photocurrent improvement of ca. 85% over planar alpha-Fe2O3 thin film reference was registered demonstrating the potential of this host-guest approach.