La₂Ti₂O₇ doped with Pt, obtained by the sol--gel method, with photocatalytic activity in the oxidative degradation of ethanol

Introduction and Aim: Perovskites are materials with increasing applications in a variety of domains, including catalysis and photocatalysis [1-3]. The oxidation of organic compounds by sunlight is significant for several reasons, including its low cost, its ability to purify air and water [4], and its potential as an alternative to the selective synthesis of high-value oxygenated compounds [5]. The aim of this work is to study the synthesis of La₂Ti₂O₇ perovskite through the sol--gel method and to test its photocatalytic activity in oxidative ethanol degradation under simulated solar light.

Methods: Materials used: lanthanum (III) nitrate hexahydrated [La(NO₃)₃x6H₂O] and titanium (IV) isopropoxide [Ti[OCH(CH₃)₂]₄] as precursors, glacial acetic acid (CH₃COOH) and isopropanol (i-C₃H₇OH) as a solvents, and PtCl₄ as a dopant. The reaction products of gas phase oxidation processes were analyzed by gas phase chromatography (GC-TCD and GC-FID).

Results: The structural and morphological comparison of nanopowders was accomplished by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with EDX, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible spectroscopy (UV–Vis), and specific surface area and porosity analysis (BET). Their photocatalytic activity was evaluated by the oxidative photodegradation of ethanol under simulated solar irradiation. The highest conversion of ethanol (29.75%) was obtained in the case of the Pt-doped sample.

Conclusions: Nanopowders of La₂Ti₂O₇ (LTA) were prepared by the sol--gel method. The effect of the dopant on the properties of the Pt-doped powder was evaluated. The samples' morphology revealed nanoparticle aggregates with well-defined mesopores. The photocatalytic activity in terms of ethanol conversion and selectivity to CO₂ was increased by the addition of platinum to the LTA catalyst. Consequently, these powders demonstrate potential applications for air depollution technologies.