A photocatalytic approach in micro arc oxidation of WO3–TiO2 nano porous semiconductors under pulse current
A photocatalytic approach in micro arc oxidation of WO3–TiO2 nano porous semiconductors under pulse current
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DOI：
10.1016/j.matchemphys.2011.03.056
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发表时间：
2011-08
影响因子：
4.6
通讯作者：
M. Bayati;F. Golestani-Fard;A. Moshfegh;R. Molaei
中科院分区：
文献类型：
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作者：
M. Bayati;F. Golestani-Fard;A. Moshfegh;R. Molaei
由于紫外线（UV）照射在实际应用中不能长时间应用，因此有必要开发窄带隙光催化剂，以在可见光照射下分解环境污染物。采用微弧氧化法制备了（WO 3）x-（TiO 2）1− x纳米多孔膜，并研究了电流类型对其物理化学性能的影响。通过SEM技术进行的形态学研究表明，孔径和粗糙度随频率降低而增加，随占空比增加而增加。脉冲生长层具有更精细的结构相比，在直流电下制造。XRD和XPS分析结果表明，涂层由金红石、金红石和氧化钨组成。施加脉冲电流可使其相对含量增加。MAO生长的TiO 2和WO 3-TiO 2层的带隙能量分别为3.14和2.96 eV。在脉冲电流下制备的层在紫外和可见光照射下表现出更高的光活性相比，在直流电下生长的层。亚甲基蓝（MB）被用作模型材料，以检查层的光催化性能。在紫外和可见光照射下，脉冲合成的WO 3-TiO 2层的最大MB光降解反应速率常数分别为0.0269和0.0129 min-1。对于在直流电下生长的层，速率常数较低，分别为0.0228和0.0099 min-1。
Since ultraviolet (UV) irradiation cannot be applied for a long time in practical applications, it is necessary to develop a narrow band gap photocatalyst to decompose environmental pollutants under visible irradiation. In this research, (WO3)x–(TiO2)1−xnano-porous layers were fabricated by micro arc oxidation (MAO) and influence of the electrical current type on their physical and chemical properties was investigated. Morphological studies, performed by SEM technique, revealed that pore size and roughness decreased with the frequency and increased with the duty cycle. The pulse-grown layers had a finer structure when compared to those fabricated under direct current. XRD and XPS results showed that the layers consisted of anatase, rutile, and tungsten oxide phases. Applying pulse current resulted in higher anatase relative contents. Band gap energies of the MAO-grown TiO2and WO3–TiO2layers were respectively measured as 3.14 and 2.96 eV. The layers fabricated under pulse current exhibited higher photoactivity under ultraviolet and visible illuminations as compared to the layers grown under direct current. Methylene blue (MB) was used as a model material to examine photocatalytic performance of the layers. Maximum MB-photodegradation reaction rate constants over the pulse-synthesized WO3–TiO2layers were measured as 0.0269 and 0.0129 min−1for ultraviolet and visible irradiations. For layers grown under direct current, the rate constants were lower, i.e. 0.0228 and 0.0099 min−1respectively.