Poly 3-Thenoic acid sensitized, Copper doped anatase/brookite TiO2 nanohybrids for enhanced photocatalytic degradation of an organophosphorus pesticide

Abstract

A series of heterogeneous poly 3-Thenoic acid (P3TA) sensitized, Copper (Cu) doped anatase/brookite TiO2 (Cu-TiO2) nanohybrid photocatalysts (P3TA/Cu-TiO2) were facilely synthesized using modified sol-gel method by taking different weight percentages (wt%) of P3TA to TiO2 at 20 °C temperature. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet-Visible diffuse reflectance spectroscopy (UV–vis DRS), Field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), High resolution transmission electron microscopy (HRTEM) and Brunauer-Emmet-Teller (BET) surface area analyses were performed to characterize the as prepared nanohybrids and their photocatalytic performances were then investigated by degrading an organophosphorous pesticide (malathion) under visible light irradiation. The characterization results revealed that P3TA surface sensitization and Copper doping in TiO2 lead to formation of agglomerated multi-particle nanohybrids with good thermal stability compared to pure TiO2. The nanohybrids exhibited a strong and broad absorption in visible range, good adsorption capacity and enhanced photocatalytic activity indicated the narrowed bang gap, decreased particle size and increased surface area of TiO2 nanoparticles. Surface chemical composition analysis showed the presence of the constituent elements of both the P3TA and Cu-TiO2 nanoparticles confirmed the strong interfacial interaction between the P3TA and Cu-TiO2,which further supported by FT-IR results. Photoluminescence and radical scavenger experiments confirmed that hydroxyl radicals (OH) are the main reactive species responsible for the oxidative degradation of malathion. Effects of different nanohybrid/malathion operating conditions on the photocatalytic activity were investigated and a simple plausible mechanism was proposed accordingly.