The effect of introducing f-electron on the hydrogen evolution rate of KLa1-xLnxTiO4 (Ln = Pr, Yb) photocatalysts

KLaTiO 4 was found to be good hydrogen evolution catalysts with a hydrogen evolution rate of 9.54(11) μmol·hr −1 . It has a relatively high bandgap of 4.09(13) eV meaning that it is only active as a photocatalyst under irradiation by ultraviolet-light. KLaTiO 4 was doped, by partially replacing lanthanum with praseodymium or ytterbium, to observe the effect of f -electrons on photocatalysis, yielding two solid solution series: KLa 1- x Pr x TiO 4 and KLa 1- x Yb x TiO 4 ( x = 0.005, 0.01 and 0.03). Both KLa 1- x Pr x TiO 4 and KLa 1- x Yb x TiO 4 are isostructural with undoped KLaTiO 4 . KLa 1- x Pr x TiO 4 showed no activity as a photocatalyst whereas KLa 1- x Yb x TiO 4 produced hydrogen at a lower rate than KLaTiO 4 . The reasons for this behaviour are described.