One step solvothermal synthesis of ultra-fine N-doped TiO2 with enhanced visible light catalytic properties

Abstract

Herein, we report the one-step solvothermal synthesis of a highly crystalline nitrogen doped TiO₂ (N-TiO₂) comprised of ultra fine particles (∼4 nm) with N-methyl-2-pyrrolidone (NMP) as solvent and doping agent. The method yields a highly crystalline, high surface area N-TiO₂ of pure anatase nature and is attributed to the use of organic solvents alone. The N-TiO₂ exhibited higher visible light (>400 nm) catalytic activity (∼50% increase) in the photodegradation of rhodamine B (RhB) compared to that of the commercial P25. Annealed N-TiO₂ (aN-TiO₂) showed a ∼70% increase in the visible light degradation of RhB and nearly 100% increase in transient photocurrent density to that of P25. The improvement in the visible light photoactivity of N-TiO₂ and aN-TiO₂ is assigned mainly to the improved visible light response because of the narrowed the band gap by introducing intra-band electronic states and reduced charge transfer resistance and the comparatively better performance of aN-TiO₂ is assigned to the additional Ti³⁺ defect states caused by oxygen vacancies formed during annealing.