Biogenic N–P-codoped TiO2: Synthesis, characterization and photocatalytic properties

Four typical kinds of crop seeds are studied as non-metallic bio-precursors to synthesize biogenic N–P-codoped TiO2 (BNP-TiO2). The as-prepared BNP-TiO2 samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen-adsorption measurement and UV–Vis spectroscopy. The results show that BNP-TiO2 possesses single anatase phase with mesopore structures, and nitrogen and phosphorus contained in original crop seeds are self-doped into the lattice as anions and cations, respectively. Besides, BNP-TiO2 exhibits a strongly enhanced absorption in the UV–Vis light range and red shift of the absorption edge, implicating the highly efficient light-harvesting capacity and sensitization towards visible light. Furthermore, experiments of crystal violet degradation under Xe lamp irradiation indicate superior photocatalytic activity of BNP-TiO2, of which the degradation rate is almost three times that of common TiO2. Circled photocatalytic degradation also shows good photocatalytic stability of BNP-TiO2. This work may pave a new and facile pathway of utilizing discarded biomass to synthesize desirable element-doped metal oxides based on biomass precursors.