Bi-element gradient doped B/N-TiO2-x synthesized by one-step solvothermal method enhances the photocatalysis of Cr(VI)

Abstract

Studying the influence of non-uniform distribution of bi-element doping on the surface structure and photocatalytic performance of TiO2 in interface photocatalytic processes can be an interesting research topic. Taking B/N bi-element doped TiO2 as an example, this article reports an extremely simple gradient doping method of TiO2 and its enhancement mechanism for high concentration wastewater treatment. The surface enrichment and doping of B caused by electrostatic and atomic radius factors changed the charge properties of the complex during the induction of in-situ reduction of Ti4+. The defects in gap N and Ti3+ lead to the formation of intermediate states, resulting in a narrowing of the band gap of the composite to 2.58 eV. The gradient doping of two atoms endows the optimal photocatalyst with a larger specific surface area (114 m2∙g), stronger photocurrent response (0.179 mA·cm−2), suitable Ti3+/Ov double defect structure, and surface positive charge properties. These characteristics improve the effective treatment of high-concentration pollutants by the preferred B2/N-TiO2-x [e.g., 0.0059 min−1 for 0.5 g·L-1 Cr(VI)] and sustainable treatment (removal efficiency > 90 % within 5 cycles). The synthesis strategy will provide a fast, simple, and safe method for the design and synthesis of new TiO2 based catalysts in the future.