The effect of Au cocatalyst loaded on La-doped NaTaO₃ on photocatalytic water splitting and O₂ photoreduction

Photocatalytic water splitting over La-doped NaTaO₃ (NaTaO₃:La) was improved by loading with Au cocatalyst which works as H₂ evolution sites. NaTaO₃:La loaded with Au by an impregnation method showed higher and more steady activity for water splitting than that by a photodeposition method. This difference in the activity for water splitting was related to the O₂ photoreduction on the loaded Au cocatalyst, which is one of the backward reactions of water splitting. The impregnated spherical Au cocatalyst suppressed the O₂ photoreduction by photogenerated electrons more efficiently than the photodeposited hemispherical Au cocatalyst, because the perimeter of Au/NaTaO₃:La interface which produces activated O₂ molecules was smaller in the impregnated Au than the photodeposited Au.