Photocatalytic oxygen evolution with a high efficiency was achieved using tantalum nitride (Ta 3N 5) quantum dots (QDs) coupled TaON hollow spheres (Ta 3N 5-TaON). TaON hollow spheres coupled with the surface enriched Ta 3N 5 QDs were prepared by an in situ chemical reduction route in ammonia solution at -45 °C and were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, UV-vis diffuse reflectance spectra and photoluminescence spectra. The Ta 3N 5-TaON composites containing 4 mol% Ta 3N 5 QDs showed a high rate of O 2 production at 208.2 μmol h -1 with an apparent quantum efficiency of 67% under 420 nm light. The rate of oxygen formation of the Ta 3N 5-TaON heterojunction was 3.3 times higher than that of the pristine TaON hollow spheres. Furthermore, relative photoelectrochemical properties of Ta 3N 5-TaON composite photoelectrodes were investigated. The resulting 4 mol% Ta 3N 5-TaON heterojunction films exhibited a photocurrent of ca. 2.7 mA cm -2 under visible light irradiation at 1.0 V vs. SCE in Na 2SO 4 solution. This excellent photocatalytic activity is ascribed to the Ta 3N 5 QDs that alter the energy levels of the conduction and valence bands in the coupled semiconductor system and the slow recombination of photogenerated electron-hole pairs. Moreover, the Ta 3N 5-TaON composite exhibited strong durability which could be attributed to the inhibition of Ta 3N 5 QDs leaching owing to its strong interaction with TaON.
ASJC Scopus subject areas
- Materials Chemistry