(387f) Synthesis and Characterization of Nitrogen-Doped Sr4Nb2O9 and Sr4Ta2O9 photocatalyst By Mechanochemical Method
Initially, Sr4Nb2O9 or Sr4Ta2O9 were synthesized by a solid-state reaction method at 1000â for 9 h in air. Afterward, nitrogen-doping to the resulting samples was carried out by the mechanochemical treatment. In the experiment, a planetary ball mill (Frisch, P-7) was used to grind Sr4Nb2O9 or Sr4Ta2O9 and CO(NH2)2 (15wt%) at speed of 100-700 rpm for 0.5 to 12 hour, and then the obtained samples were heated at 400â in the air for 1 hour to remove the unreacted CO(NH2)2.
The results of the X-ray diffraction (XRD) analysis show that after the nitrogen doping treatment using mechanohemical method, although the decrease of the peak intensity was observed, the original structures of Sr4Nb2O9 or Sr4Ta2O9 were maintained. In addition, the absorption spectrum for all the treated samples were shifted to the visible light region. Then, we examined the effect of rotation speed and time during the mechanochemical treatment on crystallinity and visible light absorption of the resulting samples. The results show that there is a trade-off relationship between the degree of crystallinity and the amount of visible light absorption in the change of rotation speed and time.
Subsequently, hydrogen generetion property of the resulting sample was tested under visible light irradiation condition.The results show that Sr4Nb2O9-N prepared under the condition of the rotation speed of 600 rpm for 1 h showed the highest hydrogen generation activity among the prepared samples in this study. The results indicate that the mechanochemical methods is an effective method to synthesize visible light responsive photocatalyst with much safer and simpler condition compared to the conventional methods.