Activating Hematite Nanorod Photoanode via Fluorine-Doping and Further Surface Fluorination for Enhanced Oxygen Evolution Reaction
Poor charge separation and sluggish oxygen evolution reaction (OER) kinetics are two typical factors blocking the photoelectrochemical (PEC) application of hematite. Dual modification strategies via heteroatom doping and surface treatment are attractive strategy to overcome the above problems. Herein, for the first time, hematite nanorod photoanode was ameliorated via fluorine treatment (F-treatment) in both bulk and surface, enabling simultaneously facilitating charge separation from the interior to the interface. Accordingly, the novel photoanode (FeFx/F-Fe2O3) exhibited outstanding PEC water oxidation activities, with the photocurrent density 3-fold improved than that of unmodified α-Fe2O3. More specifically, fluorine doping (F-doping) in hematite bulk remarkably increases the charge carriers’ concentration and endows it a favorable electrical conductivity for rapid charge transfer. Further surface F-treatment on F-doped α-Fe2O3 (F-Fe2O3) enriches the F-Fe bonds on the surface, which significantly boost the OER kinetics and thereby inhibit the detrimental surface charge recombination. As a consequence, the efficiencies of bulk electron-hole pairs separation and surface hole injection were increased by 2.8 and 1.8 times respectively. This work points to fluorine modulation as an attractive avenue to advance the PEC performance of metal oxide-based photoelectrode materials.