Visible light-induced photo-degradation of methylene blue by n-p heterojunction CeO2/CuS composite based on ribbon-like CeO2 nanofibers via electrospinning

Composite of n-type CeO2/p-type CuS heterojunctions as adsorbent/photocatalysts were successfully synthesized based on electrospinning technique, calcination and hydrothermal methods following growth of CuS nanostructures on the primary CeO2 nanofibers, while laterally were characterized by FE-SEM, EDS, XRD, DRS and FT-IR. Present composite in aqueous solutions was applied for methylene blue (MB) degradation was investigated under visible light radiation (LED). DRS analysis illustrates that CeO2/CuS n-p heterojunction exhibited enhanced absorption in the visible region with band gap of 2.55. Under optimal conditions (3.0 mg L-1 MB, 1 g L-1 of CeO2/CuS dosage and 40 min irritation time at pH of 6.0) lead to 89.80% photocatalytic decomposition of MB. The CeO2/CuS composite nanofiber as photocatalyst exhibited enhanced visible-light absorption and reduced charge recombination, as compared to bare CeO2 ribbon-like nanofibers, due to the interfacial charge transfer effect among the CuS species and CeO2. The first-order kinetics based on Langmuir-Hinshelwood (L-H) model was able for effective fitting empirical data, while its rate constant (k(obs)), L-H rate constants (k(r)) and L-H adsorption constants (K-A) were 0.0625 min(-1), 0.157 mg min(-1) L and 0.24 L mg(-1) by CeO2/CuS in optimum condition. The reusability of CeO2/CuS composite is relatively undesirable in view of the recycling of photocatalysts. (C) 2019 Published by Elsevier Ltd.