Enhanced Photocatalytic Activity of as-Prepared Sodium Titanates for <I>m</I>-Dinitrobenzene Reduction and Sulfosulfuron Oxidation

Abstract

This paper demonstrates the preparation and photocatalytic activity of sodium titanate nanorods and nanotubes prepared by hydrothermal method using P25-TiO2 as the precursor. XRD results confirmed the monoclinic structure of sodium titanate nanorods obtained after calcinations of orthorhombic sodium titanate nanotubes at 800 °C for 2 h. The BET surface area of sodium titanate nanotubes (176 m2 g-1) was significantly reduced for sodium titanate nanorods (21 m2 g-1) formation because of the collapsing of the hollow interior of the former during its high temperature sintering. The selective formation of m-diaminobenzene by the photoreduction of the m-dinitrobenzene was found to be comparable by sodium titanate nanorods (89.5 ± 0.5%) and P25-TiO2 (98.2 ± 0.8%), whereas Au-deposition (0.5 and 2 wt%) onto sodium titanate nanorods notably altered the products (m-nitroaniline and m-diaminobenzene) distribution after 8 h of UV-light irradiation and which was confirmed later by GC-MS analysis. This high photoactivity of as-prepared nanorods could be credited to better delocalization and longer relaxation lifetime (68 µs) of photoexcited e-/h+ pairs along the length of crystalline sodium titanate nanorods than P25-TiO2 (45 µs) as measured from Time-resolved spectroscopy. The photooxidation of sulfosulfuron herbicide (1000 ppm) and corresponding CO2 formation was found to be highest with sodium titanate nanotubes due to the presence of more hydroxyl groups over the largest surface area that dominates over its least relaxation lifetime (41 µs).

Photodegradation of Imidacloprid Insecticide by Ag-Deposited Titanate Nanotubes: A Study of Intermediates and Their Reaction Pathways

“…TNT were prepared through the hydrothermal route using P25-TiO 2 as reported , by our group. Surface modification of TNT by Ag loading (0.2–1.0 wt %) was carried out by irradiating (125 W Hg arc lamp) the deaerated solution (50% v/v isopropyl alcohol) of TNT and AgNO 3 (equivalent to 0.2, 0.5, and 1.0 wt % of Ag) as reported , recently by our group. Catalysts thus obtained are termed 0.2-Ag-TNT, 0.5-Ag-TNT, and 1.0-Ag-TNT, respectively.…”

“…Highly porous monoclinic sodium titanate nanotubes possessing high surface area, interlayer water molecules, scroll structure, and thin wall thickness for better charge transport and charge diffusion properties have been studied for the photocatalytic degradation − of many organic pollutants. Generally, TNT exhibit higher photocatalytic activity (PCA) − ,, than commercially available most photoactive P25-TiO 2 (P25). For instance, Zhu et al and Antoino et al showed their 5 and 7 times higher activity than P25 for degradation of sulforhodamine and methyl red dyes, respectively.…”

“…For example, Morgado et al demonstrated that TNT having 2–5 wt % of Na can show improved PCA for oxidation of rhodamine-B, whereas Qumar et al showed its negligible and higher PCA below and above the 300 °C calcination temperature, respectively. However, calcination of TNT at >700–800 °C transforms them into orthorhombic nanorods with change in Ti–O bond length, having much less surface area and dehydroxylated surface with a decent PCA − relative to that of P25.…”

“…Hence, bare/metal-loaded TNT despite having Na (generally decrease the activity of TiO 2 catalyst) and the high-temperature treatment have proven to show better activity than P25 for the degradation of dyes. Therefore, they can be utilized for mineralization of other large heteroatom(s) containing molecules such as pesticides and have been recently studied by our group. , …”

Plasmonic coinage metal–TiO2hybrid nanocatalysts for highly efficient photocatalytic oxidation under sunlight irradiation

“…It can be easily understood through time-resolved spectroscopy. Though reports are available regarding the electron charge carrier time of NC as a function of shape and size of the semiconductors, 60 the influence of the nature of the metal onto the band edge and trapping states still remains a challenge. The charge carrier's relaxation dynamics of M-TiO 2 relative to P25-TiO 2 are shown in Fig.…”