Study On The Hydrothermal Synthesis Of NaNbO₃Powder And Its Photocatalytic Properties

In this paper, hydrothermal and solvothermal method were used to synthesizethe niobium sodium Photocatalyst materials with different morphologies, and theinfluence of different reaction conditions were explored. XRD and SEM were usedto detect the phase of the samples, and observe the morphology of the samples,respectively. The UV-Visible （UV-Vis） diffuse reflectance spectra of the sampleswere recorded at room temperature in the range of250-700nm using a UV-Visspectrophotometer. In addition, the degradation of methyl orange （MO） solution bythe products was studied.In the first part, Nb₂O₅and NaOH were used as raw material, the pure-phasewell-crystallized niobium sodium powders were synthesized in the hydrothermalsystem. Compared with the traditional high temperature solid state reaction, theenergy consumption of this method is lower, the proceduse of this method is simple,and the product with smaller particles can be achived. The experimental resultsshow that when the temperature reaches to160℃, the reaction time extends to24hours, the ratio of sodium and niobium is not less than8:1, and the concentration ofNaOH is greater than1M, the pure-phase niobium sodium can be synthesized byhydrothermal method.In the second part, NaNbO₃nanowires were successfully prepared through asimple solvolthermal route followed by calcinations. The amount of alcohol in themixed solvent was identified as a key factor in the morphology-controlled synthesisof NaNbO₃nanowires and the mechanism for the formation of the hydrothermalproduct was investigated. When the alcohol content reached to30ml,well-developed nanowires were obtained. After annealing at550℃for4hours,NaNbO₃nanowires with the same morphology could be obtained. Compared withthe NaNbO₃cube samples, the absorption edge of the NaNbO₃nanowire samplesappeared to be a little blue shift. Moreover, NaNbO₃nanowires have higherspecific surface area (15.8m²·g^-1) and better degradation rate of MO （67.2%）.In the third part， NaNbO₃and Fe₂O₃were composited by the solvothermalmethod. The Fe₂O₃/NaNbO₃composite photocatalyst were successfully prepared.The photocatalytic experiments indicate the Fe₂O₃/NaNbO₃compositephotocatalyst exhibits good performance for photocatalytic degradation rate of MOunder visible light irradiation. The impact of different doping amount on the degradation rate of MO was discussed. From the UV–Vis absorption spectra ofproduct with different doping amount of Fe₂O₃and the experiment about thephotocatalytic degradation of methyl orange, we can see that when the dopingamount of Fe₂O₃is25%, after2h irradiation, the degradation rate reachedto18.6%.