Aloe-vera flower shaped rutile TiO2 for selective hydrogenation of nitroaromatics under direct sunlight irradiation

Abstract

This study reveals the fabrication of a sunlight receptive flower shaped rutile TiO2 microstructure (F-TiO2) for the selective photoreduction of nitroaromatics. The crystalline F-TiO2 possesses small band gap (∼2.8 eV) and large specific surface area (193 m2g−1). Moreover, the F-TiO2 exhibited higher relaxation time (120 µs) for the electron-hole pairs due to its brilliant multi dimensional morphology that enables shorter diffusion path and multiple scattering of active sites. The experimental results revealed the superior photocatalytic activity of the F-TiO2 microstructure in contrast to active P25 and rutile TiO2 (obtained from thermally treated P25 at 800 °C for 4 h) for the reduction of nitrobenzene, m-dinitrobenzene and 2,2-dinitrobiphenyl in 50% aqueous isopropanol (hole scavenger) to aniline (42–72%), m-nitroaniline (37–42%), m-phenylenediamine (88–100%) and benzo[c]cinnoline (80–94%) respectively under UV and direct sunlight irradiation. The quantitative estimation of byproducts like acetone and hydrogen (H2) produced from iso-propanol oxidation and water splitting during instant reduction of nitroaromatics to aromatic amines is well correlated and explained on the basis of its beneficial surface structural and electronic properties. Keywords: Flower shaped rutile TiO2, Low temperature synthesis of rutile phase, Lower recombination rate of charge carriers, Selective photocatalytic nitroaromatic reduction, Sunlight irradiation