Dr. Yuichi Negishi, Professor, Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Japan

Title: Creation of Highly Water-Splitting Photocatalyst by Controlling Cocatalyst

Abstract: Our aim in this work was to activate a photocatalytic material which could be used as a practical material. Therefore, in these studies, we used BaLa₄Ti₄O₁₅ as the photocatalytic material because it is one of the most advanced water-splitting photocatalytic compounds. We synthesized glutathione (SG)-protected Au₂₅(SG)₁₈, and these clusters were subsequently adsorbed onto the surface of a BaLa₄Ti₄O₁₅. Au₂₅ was subsequently loaded onto the BaLa₄Ti₄O₁₅ by removing the ligands through calcination. Various characterizations confirmed that almost none of the Au₂₅ aggregated on the BaLa₄Ti₄O₁₅ surface and that the majority of the ligands had been removed. The resulting Au₂₅-loaded BaLa₄Ti₄O₁₅ (Au₂₅-BaLa₄Ti₄O₁₅) showed photocatalytic activity 2.6 times higher than BaLa₄Ti₄O₁₅ (AuNP-BaLa₄Ti₄O₁₅) loaded with larger gold nanoparticles (10–30 nm) using a conventional photodeposition method. This result indicates that the use of fine Aun(SG)m clusters as a co-catalyst can produce a highly active water-splitting photocatalyst. Further experiments revealed that the photocatalytic activity continuously increased with decreasing size of the Aun cluster co-catalyst.

Keywords: photocatalysts, water splitting, metal cluster