A series of single crystals and ceramics were prepared and evaluated as electrodes in the photoassisted electrolysis of . Samples of possess an optical bandgap of 1.99 eV and a flatband potential of approximately , which compares with 3.03 eV and , respectively, in . For in the range , the flatband potential increases to approximately . Both observations, the narrower bandgap and varying flatband potential, are attributed to the existence of a primarily d‐band, of varying width and density, interjected in the bandgap.