Facile synthesis of boron and nitrogen doped TiO2 as effective catalysts for photocatalytic degradation of emerging micro-pollutants

Abstract

The development of photocatalysts for efficient photodegradation of emerging water pollutants is a subject of global concern in recent years. In this study, the photophysical properties of TiO2 were modified by doping with different concentrations of boron (B-TiO2) and nitrogen (N-TiO2) by following a sol–gel route of synthesis. The type and concentration of dopants were optimized to achieve maximum degradation of acetaminophen (ACT) and monocrotophos (MCP) in aqueous solutions. UV DRS analysis shows that the bandgap of TiO2 (3.2 eV) reduced up to 2.96 and 2.27 eV in B-TiO2 and N-TiO2 samples, respectively. The presence of dopants inside the crystal lattice of doped TiO2 was confirmed with X-ray diffraction (XRD), Micro Raman, Fourier Transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The XRD data confirmed that the presence of these dopants promotes the rutile phase transformation in TiO2 to various extents. The doping of B decreased the surface area and pore volume of TiO2, whereas N doping had increased these properties. The XPS spectra showed the formation of Ti-O-B and Ti-O-N type linkage, indicating the presence of interstitial B and substitutional N atoms in TiO2 crystal lattice. The B doped samples exhibit more enhancement in photodegradation efficiency as compared to N doped samples. Under optimized conditions, 5% B-TiO2 showed 95% and 71% degradation of ACT and MCP, respectively. The degradation pathway for both ACT and MCP involving their intermediates was discussed through Mass spectrometry analysis. The cost-effectiveness of the most efficient doped catalysts and commercial catalysts were compared with the ACER tool and turnover frequency.