Ghafoor Samina, Ata Sadia, Mahmood Nasir, Arshad Salman Noshear
Department of Chemistry, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan.
Institute of Chemistry, University of the Punjab, P.O. Box 54590, Lahore, Pakistan.
Sci Rep. 2017 Mar 21;7(1):255. doi: 10.1038/s41598-017-00366-7.
TiO nanofibers, with mean diameter ~200 nm, were fabricated by electrospinning and successfully photosensitized with low bandgap AgS nanoparticles of 11, 17, 23 and 40 nm mean sizes, with corresponding loading of 4, 10, 18 and 29 wt.% AgS, respectively. 17 nm AgS@TiO nanofibers exhibited optimal activity in the photodegradation of methylene blue under simulated sunlight with pseudo-first order rate constant of 0.019 min compared to 0.009 min for pure TiO nanofibers. In spite of greater visible-light absorption and reduced bandgap, larger than 17 nm AgS nanoparticles exhibited sluggish photodegradation kinetics probably due to less photo-induced carriers generation in TiO and reduced electron injection rates from the larger sized AgS into TiO. Furthermore, a UV-O surface treatment induced excess Ti surface states and oxygen vacancies which synergistically enhanced the photodegradation rate constant to 0.030 min for 17 nm AgS@TiO sample which is ~70% better than the previously reported for AgS/TiO hierarchical spheres. This was attributed to the efficient charge separation and transfer driven by increased visible-light absorption, bandgap narrowing and reduced electron-hole recombination rates. The present study demonstrate the potential utilization of AgS@TiO nanofibers in filtration membranes for removal of organic pollutants from wastewater.
通过静电纺丝制备了平均直径约为200nm的TiO纳米纤维，并分别用平均尺寸为11nm、17nm、23nm和40nm的低带隙AgS纳米颗粒成功进行了光敏化处理，相应的AgS负载量分别为4wt.%、10wt.%、18wt.%和29wt.%。在模拟太阳光下，17nm AgS@TiO纳米纤维在亚甲基蓝的光降解中表现出最佳活性，其准一级反应速率常数为0.019min⁻¹，而纯TiO纳米纤维的该常数为0.009min⁻¹。尽管大于17nm的AgS纳米颗粒具有更大的可见光吸收和更小的带隙，但它们的光降解动力学却很缓慢，这可能是由于TiO中光生载流子的产生较少，以及较大尺寸的AgS向TiO的电子注入速率降低所致。此外，紫外光-氧表面处理诱导了过量的Ti表面态和氧空位，协同将17nm AgS@TiO样品的光降解速率常数提高到0.030min⁻¹，比之前报道的AgS/TiO分级球体的光降解速率常数高出约70%。这归因于可见光吸收增加、带隙变窄和电子-空穴复合率降低所驱动的有效电荷分离和转移。本研究证明了AgS@TiO纳米纤维在过滤膜中用于去除废水中有机污染物的潜在应用价值。
