A Versatile Method For Controllable Synthesis Of Phosphorus Doped Metal Oxides And Their Water Treatment Properties

Morphology modulation or lattice doping is employed to enhance the photocatalytic activities of the semiconductor materials.However,combining crystal lattice doping with morphology modulation in a one-step synthesis procedure is a very important but challenging task.Herein,a versatile hydrothermal synthesis strategy was developed to fabricate the P-doped metal oxide semiconductors.Sodium citrate is used as the complexing agent,sodium hypophosphite as the phosphorus source and metal salt as the precursor.1.P-doped TiO₂ hollow submicrospheres were synthesized via a simple one-step hydrothermal method.P element was incorporated into the crystal lattice of hollow submicrospheres,resulting in the decrease of crystallite size,redshift in the light absorption and enhancement of charge separation efficiency.Sodium hypophosphite induced simultaneous P doping and hollowing process of the TiO₂ submicrospheres.The hollow structure and P doping amount can be finely tailored by tuning the P/Ti molar ratio.The hollow interiors and the porous shells result in the obvious enhancement of the specific surface area for the doped sample.Compared to the undoped TiO₂,the P-doped TiO₂ hollow submicrospheres showed higher photocatalytic activities for methylene blue?MB?degradation under simulated sunlight irradiation.In particular,the product with P doping amount of 0.73 wt%exhibited the highest photocatalytic activity,which was 4.8 times and 5.7 times faster than undoped TiO₂ and P25.The enhanced photocatalytic activity could be attributed to the synergistic effect of the hollow submicrostructures and P doping in TiO₂ crystal lattice.2.A novel core-shell microsphere was synthesized via this simple hydrothermal reaction.The light green amorphous product with a particle size of 2-4?m is identified as the Fe³⁺complex,in which both the citrate and the phosphate as the complex anions.It was found that the molar ratio of sodium citrate to sodium hypophosphite less than 3 is essential to form the core-shell structures.3.Multi-cavity P-doped a-Fe₂O₃ microspheres were obtained by the thermal treatment of the precursor at 650?.The cavities connect with each other via the curled or twisted nanowalls to form a cross-linked inner space.P exists in the form of Fe-O-P bonds in?-Fe₂O₃ lattice.The multi-cavity P-dopeda-Fe₂O₃ microspheres demonstrated a significantly enhanced photocatalytic activity for As???oxidation compared with the pure?-Fe₂O₃ under simulated sunlight irradiation.The optimized demonstrates a high rate constant,which is 18.3 times higher than that of the pure?-Fe₂O₃.The product also showed an excellent adsorption capacity towards the generated As???.As a result,As???could be completely eliminated through the simultaneous photocatalytic oxidation and adsorption process.The P doping significantly enhances the separation efficiency of photogenerated hole-electron pairs and obviously prolong the carries lifetime.4.The hierarchical P-doped ZrO₂ flower microspheres were synthesized by one-step hydrothermal method.The microsphere is composed of a dense core and the nanosheets cross-linked outer shell.The P doping led to significant changes in the morphology of ZrO₂ and increased its specific surface area by 4.7 times.Compared to pure ZrO₂,the P-doped ZrO₂ flower microspheres demonstrate higher adsorption capacity for As???and As???.The increased specific surface area significantly facilitates the transfer and adsorption capacity of arsenic on the surface of the product.In summary,the synthetic strategy can be used to prepare a variety of P-doped metal oxides.Combining lattice doping and morphology modulation in one step is the most striking feature of the synthetic strategy.This work enables us a new approach to rational design and fabrication of non-metal element doped photocatalysts combined with unique morphology via a simple procedure.