Enhanced efficiency of hematite photoanode for water splitting with the doping of Ge

Ge doped α-Fe 2 O 3 nanowires are synthesized through a hydrothermal procedure with GeO 2 as a precursor and investigated as photoanodes for water splitting. The content of Ge in the photoanode rises with the increase of the amount of GeO 2 in the precursor solution . A proper amount of Ge facilities the preferred oriented growth of the (110) plane of α-Fe 2 O 3 , while excessive Ge hinders the growth of α-Fe 2 O 3 crystals. The doping of Ge increases the absorption efficiency and decreases the recombining rate of the photogenerated electrons and holes. Ge also improves the density and transfer rate of the charge carriers in the photoanode. Ge doped α-Fe 2 O 3 photoanode exhibits a highest photocurrent density of 0.92 mA cm −2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G simulated sunlight, which is nearly twice of that obtained by pure α-Fe 2 O 3 under the same condition.