Effect of nitrogen-doping temperature on the structure and photocatalytic activity of the B,N-doped TiO2

B,N-TiO2 photocatalysts were synthesized by boron doping firstly and subsequently nitrogen doping in NH3 at variable temperatures. The effects of the nitrogen doping temperature on the structure and photocatalytic activity of the B,N-codoped TiO2 were investigated. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectrum (DRS), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated with photocatalytic degradation of methyl orange dye (MO) under visible light and UV-visible light irradiation. The results suggested that the boron and nitrogen can be incorporated into the TiO2 lattice either interstitially or substitutionally or both, while the Ti-O-B-N structure plays a vital role in photocatalytic activity in visible light region. The optimal nitrogen doping temperature is 550 oC. Higher temperature may form many oxygen vacancies and Ti3+ species, resulting in the decrease of photocatalytic activity in visible light. -- Graphical abstract: The changes of photocatalytic activity of B,N-TiO2 with variable nitrogen doping temperatures are attributed to the transformation of surface structure and oxygen vacancies, and the Ti-O-B-N structure plays a vital role in photocatalytic activity under visible light irradiation. Display Omitted Research Highlights: →B,N-TiO2 photocatalysts are synthesized by boron doping firstly and subsequently nitrogen doping in NH3 at variable temperatures. →The boron and nitrogen can be incorporated into the TiO2 lattice either interstitially or substitutionally or both. →The temperature of nitrogen doping affects the transformation of surface structure and oxygen vacancies. The →Ti-O-B-N structure plays an important role in photocatalytic activity under visible light irradiation.