Distinct photocatalytic performances were found when Ta3N5 was synthesized from commercially available Ta2O5 or from home-made Ta2O5 starting from TaCl5 via sol-gel route. In the case of photocatalytic O2 evolution with Ag+ as a sacrificial reagent, Ta3N5 made from commercial Ta2O5 showed higher activity than Ta3N5 from sol-gel route. When the Ta3N5 photocatalysts were decorated with Pt nanoparticles in similar manner, the sol-gel route Ta3N5 show higher photocatalytic hydrogen evolution activity from 10% methanol aqueous solution than Ta3N5 from commercial Ta2O5. Detailed surface and bulk characterizations were applied to obtain fundamental insight to explain the resultant photocatalytic activities. The characterization techniques used to elucidate the bulk properties showed only negligible difference between these two photocatalysts. On the other hand, our deep surface characterization on the surface properties proved that the very thin outmost layer of Ta3N5 in a few nanometers consists of reduced state of tantalum, in contrast to the previous reports that Ta3N5 has an outmost layer in its oxidized form. The electron diffraction patterns revealed that a surface thin layer of 1-2 nm was identified as cubic TaN for both Ta3N5 synthesized from commercial and sol-gel Ta2O5 but to different extent. Electrochemical and Mott-Schottky analyses demonstrated that the TaN surface layer drastically affect the energetic picture at semiconductor-electrolyte interface, which can in turn affect the photocatalytic performance. In addition, this finding will open new direction on development of Ta3N5 photocatalyst particularly on surface properties and modification as the main focus on improving photocatalytic activity.

Interface tuning of Ta<sub>3</sub>N<sub>5</sub> photocatalyst particulates for water splitting

248th National Meeting (2014)

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Interface tuning of Ta3N5 photocatalyst particulates for water splitting

Interface tuning of Ta₃N₅ photocatalyst particulates for water splitting