Photocatalytic NOx removal using tantalum oxide nanoparticles: A benign pathway

Abstract A wet chemical-synthesized high surface area ultrafine Ta2O5 nanoparticle and its application to NOx control is reported. The as-synthesized photocatalyst is characterized using powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), transient absorption spectroscopy (TAS), UV–vis diffuse reflectance spectroscopy, and N2 adsorption (BET). The catalytic performance of these Ta2O5 nanoparticles was evaluated towards the photodegradation of nitrogen oxides (NOx) under UV–vis irradiation at room temperature. In comparison to the commercial TiO2 (Aeroxide P25 powder: 20 % rutile/80 % anatase, 50 m2/g), traditionally considered state-of-the-art material for the NOx degradation, as-synthesized Ta2O5 (41 m2/g specific surface area) nanoparticles offers NOx remediation with minimal toxic NO2 and excellent stability under UV irradiation. A 2-fold increase in the UV-photonic-efficiency (∼0.64 %) of Ta2O5 is observed compared to TiO2 P25 (∼0.30 %). NO conversion using Ta2O5 was noted to be 18.6 % compared to 8.8 % for TiO2. The UV–vis photocatalytic activity is explained on the basis of the band structure modulation of Ta2O5 due to the intrinsic defects introduced during the synthesis of the material.