Electrospun CuAl2O4 hollow nanofibers as visible light photocatalyst with enhanced activity and excellent stability under acid and alkali conditions

Photocatalysts with desirable and stable photocatalytic activity under visible light irradiation are of great significance for water purification. In this work, we prepared CuAl2O4 hollow nanofibers (HNFs) with diameters of 100-150 nm by combining electrospinning technique and subsequent annealing. The hollow structure could be obtained at appropriate heating rate (3-5 degrees C min(-1)), probably because the existence of an oxygen concentration gradient resulted in the faster decomposition of polymer on the surface than the interior of the nanofibers. The CuAl2O4 HNFs had large specific surface area for photocatalytic reactions and narrow band gap for good visible light absorption. As expected, the CuAl2O4 HNFs exhibited desirable photocatalytic activity for degrading both rhodamine B and methyl orange under visible light irradiation and the calcination temperature strongly affected the photocatalytic performance. Importantly, the photocatalytic activity was very stable at pH 3-11 due to the excellent chemical stability. Moreover, the photocatalytic mechanism was investigated based on trapping experiments and it was found that e(-), h(+) and O-center dot(2)- were the vital species in the reactions. Most of all, the CuAl2O4 HNFs could be easily recycled by sedimentation and separation because of their non-woven web structure and good mechanical stability. Therefore, the as-prepared CuAl2O4 HNFs as a promising photocatalyst may have good prospects for sustainable development and chemical engineering applications.