Photosensitization of TiO2nanofibers by Ag2S with the synergistic effect of excess surface Ti3+states for enhanced photocatalytic activity under simulated sunlight.
TiO2nanofibers, with mean diameter ~200 nm, were fabricated by electrospinning and successfully photosensitized with low bandgap Ag2S nanoparticles of 11, 17, 23 and 40 nm mean sizes, with corresponding loading of 4, 10, 18 and 29 wt.% Ag2S, respectively. 17 nm Ag2S@TiO2nanofibers exhibited optimal activity in the photodegradation of methylene blue under simulated sunlight with pseudo-first order rate constant of 0.019 min-1compared to 0.009 min-1for pure TiO2nanofibers. In spite of greater visible-light absorption and reduced bandgap, larger than 17 nm Ag2S nanoparticles exhibited sluggish photodegradation kinetics probably due to less photo-induced carriers generation in TiO2and reduced electron injection rates from the larger sized Ag2S into TiO2. Furthermore, a UV-O3surface treatment induced excess Ti3+surface states and oxygen vacancies which synergistically enhanced the photodegradation rate constant to 0.030 min-1for 17 nm Ag2S@TiO2sample which is ~70% better than the previously reported for Ag2S/TiO2hierarchical 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 Ag2S@TiO2nanofibers in filtration membranes for removal of organic pollutants from wastewater.
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.
Samina
S
Ghafoor
Institute of Chemistry, University of the Punjab, P.O. Box 54590, Lahore, Pakistan.
Sadia
S
Ata
Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, 2500, Australia.
Nasir
0000-0002-8340-1058
N
Mahmood
Department of Chemistry, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan. salman.arshad@lums.edu.pk.
Salman Noshear
0000-0002-1876-8929
SN
Arshad