Synthesis of single-crystalline, porous TaON microspheres toward visible-light photocatalytic conversion of CO₂ into liquid hydrocarbon fuels

Single-crystalline, porous TaON microspheres were prepared for photocatalysis via facile nitridation of uniform amorphous Ta₂O₅ sphere formed by hydrothermal treatment. The amorphous property facilitates shrinkage of Ta₂O₅ into the porous TaON nanostructure during the ammonification process. The porous spherical architecture of TaON plays a significant role in deciding the CO₂ photocatalytic conversion efficiency into ethanal and ethanol under visible light irradiation, relative to its counterpart from commercial Ta₂O₅, including availability of more reaction sites, easy trapping of incident illumination, and shortening of charge transfer distance from the interior to the outer surface to expedite charge separation. Loading Pt as an electron sinker over the porous TaON, boosting the separation of the photogenerated electron-hole pairs, not only improves the photoconversion efficiency, but also alters the product species.