Abstract
Hematite (α-Fe 2 O 3 ) is an intensively studied photoanode for water splitting. However, the solar-hydrogen efficiency of an α-Fe 2 O 3 photoanode remains limited because of its low conductivity and high surface recombination rate that limit its photocurrent output. In this work, hematite (α-Fe 2 O 3 ) photoanodes prepared by electroplating were investigated for their majority and minority carrier concentration and surface-trapped states. The results show that the photocurrent generation strongly depends both on the bulk doping and the interface density of states (D it ). A high electron concentration (over 1.2 × 10 20 cm -3 ) with high D it (1.4 × 10 16 cm -2 eV -1 ) may jeopardize the water splitting, with negligible photocurrent output under AM1.5 illumination. In contrast, a photocurrent is detected when the electron concentration and D it is lower than 6.1 × 10 19 cm -3 and 8.8 × 10 14 cm -2 eV -1 . This result has also been interpreted with the variation of the α-Fe 2 O 3 -electrolyte band diagram with the bias potential. © The Royal Society of Chemistry 2013.