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.

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► We achieved the increased water splitting over NaTaO3 doped with La photocatalyst by loading Au cocatalyst.
► Impregnated Au worked better as cocatalyst for water splitting than photodeposited Au.
► The impregnated Au cocatalyst suppressed the O2 photoreduction more efficiently than the photodeposited Au cocatalyst.