Dual-doping in the bulk and the surface to ameliorate the hematite anode for photoelectrochemical water oxidation

Abstract

Aiming at the drawbacks of hematite like poor conductivity and tardy oxidation kinetics, herein, we utilized dual dopants in the bulk and surface to ameliorate the situation. Specifically, doping optimal amount of Zr4+ in the hematite (Zr:Fe2O3) enhances the conductivity of hematite due to the higher charge carrier density. Further, F:FeOOH could form p-n heterojunction in bulk where a potential barrier is built up that repels electrons but prompts holes transferring to F:FeOOH for water oxidation. What’s more, the high electronegative of F- would withdraw electron from the Fe site in FeOOH, and the enhanced positive electricity of Fe3+ is beneficial for adsorption of OH– as well as enhance the conductivity of FeOOH to expedite holes transfer. As a result, the composite photoanode (F:FeOOH/Zr:Fe2O3) shows a 3.25-times enhanced photocurrent density comparing with α-Fe2O3. The special designation employs ultrathin F:FeOOH to act as both p-type semiconductor and efficient co-catalyst, avoiding redundant layer that would extend the migration distance of holes. On the top of that, the dual modification approach provides an extensive prospect for the further application of hematite.