Development of visible-light-driven photocatalysts via an interfacial photoexcitation process

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Our current findings imply that we can control p- (cathodic photoresponse) or n-type (anodic photoresponse) conductivity by a facile surface modification, instead of complicated crystal structure modifications. We have studied interfacial charge transfer (IFCT) in three-electrode photoelectrochemical system for fuel production under UV and visible-light illumination. In this study, we have investigated Cu(II)/TiO2 photo-electrode, and cathodic photoresponse was observed. H2 and O2 evolution were detected from Cu(II)/TiO2 photocathode and Pt sheet, respectively, indicating that water splitting reaction occurred without any addition of sacrificial agent. Considering the concept of IFCT, a direct electron excitation from the valence band of TiO2 to Cu(II) nanoclusters initiated water splitting reaction. On the other hand, Cr(III)/SrTiO3 photo-electrode exhibited anodic photoresponse, indicating that O2 evolution took place on this photoanode; in this case, electrons were directly excited from Cr(III) nanoclusters to the conduction band of SrTiO3 (reversed transfer path). We expect this research would be promising to further examine the direct interfacial charge transfer, not only for photocatalyst but also for other applications.