The effect of fluorine doping on the photocatalytic properties of hematite for water splitting

Fluorine-doped hematite samples with different concentrations were successfully synthesized through a hydrothermal method. The 3% F-doped hematite is found to be the optimal catalyst in this study which has a [110]-oriented structure and a remarkable photocurrent density of 1.24 mA cm−2 at 1.23 V vs. RHE under one sun irradiation, which is about ten times higher than that of bare hematite (0.12 mA cm−2). F doping also reduces the recombination of free electron–hole pairs. The shift of the Fermi level position caused by F doping leads to the decrease of charge-transfer resistance in the bulk (R1) and interface (R2) and the increase of charge carrier concentration (Nd). In addition, F doping contributes to the shadow defect. All the results indicate that 3% F is the best doping concentration.