ABSTRACT

Monoclinic WO₃ nanocuboids were synthesized via a one-pot hydrothermal method in a highly acidic environment at 180°C for different reaction times (12, 24, and 48 h). The phase transformation from orthorhombic to monoclinic and then to oxygen-deficient Magnéli phase and an increase in optical bandgap from 2.43 to 2.70 eV were observed when the reaction time increased from 12 to 24 h and then to 48 h. All samples showed photocatalytic activity towards the degradation of methylene blue (MB) under solar light irradiation, which was strongly enhanced in the presence of hydrogen peroxide (H₂O₂). Sample prepared for 24 h showed the highest MB removal efficiency of 31.4% in the absence of H₂O₂, which was enhanced to 76% and 92% when adding 0.2 and 0.5 mL of H₂O₂, respectively. These results give insights into the phase transformation and photocatalytic mechanism of WO₃ nanocuboids prepared via the hydrothermal method.

摘要

单斜晶WO ₃纳米长方体通过一锅水热法在180°C 的高酸性环境中合成，反应时间不同（12、24和48 小时）。当反应时间从 12 到 24 小时再增加到 48 小时时，观察到从正交相到单斜相再到缺氧 Magnéli 相的相变以及光学带隙从 2.43 增加到 2.70 eV。所有样品在太阳光照射下都显示出对亚甲蓝 (MB) 降解的光催化活性，在过氧化氢 (H ₂ O ₂ )存在下，这种活性得到强烈增强。在不存在 H ₂ O ₂的情况下，制备 24 小时的样品显示出最高的 MB 去除效率，为 31.4%，当加入 0.2 和 0.5 mL H ₂ O _{2 时}，分别提高到 76% 和 92% 。这些结果深入了解了通过水热法制备的 WO ₃纳米长方体的相变和光催化机制。