Decoupling Size and Electronic Effects in Doped SrTiO ₃ Photocatalysts Through Surface Area–Normalized CO ₂ Hydrogenation Rates

Abstract This study decouples size and electronic effects in Ga‐ and La,Ga‐doped SrTiO 3 photocatalysts through specific surface area (SSA) normalized CO 2 hydrogenation rates. The distinction between SSA‐normalized and apparent photocatalytic activity is crucial because gas‐sorption experiments reveal that Ga monodoping significantly increases the SSA of sol–gel synthesized SrTiO 3 , but does not enhance its SSA‐normalized photocatalytic activity in CO 2 photohydrogenation. In contrast, SSA‐normalized photocatalytic rates for La,Ga co‐doped SrTiO 3 approximately double, suggesting a true improvement in catalytic performance. These co‐doped samples show intense, sharp photoluminescence and a mid‐gap absorption feature which, using DFT calculations and oxygen annealing experiments, color centers are attributed to (). Though future studies into the identification of the active site(s) are needed to assess the true, intrinsic activity, this study highlights that SSA normalization of photocatalytic rates is helpful to disentangle key material properties that enhance the catalytic activity from mere surface area effects.