Polyaniline (PANI) particles were immobilized on electrospun polyacrylonitrile (PAN) nanofibers (NFs) to form PAN@PANI NFs via in situ polymerization at room temperature. Then, ZnO was deposited on the surface of PAN@PANI NFs by atomic layer deposition (ALD) to form PAN@PANI@ZnO NFs. The PANI and ZnO contents were well controlled by adjusting the polymerization time and the number of ALD cycles, respectively. The obtained PAN@PANI@ZnO NFs exhibited higher photocatalytic activity for the degradation of methylene blue under ultraviolet light irradiation than PAN@PANI and PAN@ZnO NFs, and the first-order degradation rate constant (k(app)) of PAN@PANI@ZnO NFs formed with 400 ALD cycles was greater than that of PAN@ZnO NFs formed with 400 ALD cycles by a factor of 2.1. The enhanced photocatalytic activity is shown to originate from the improved charge separation of photogenerated electrons and holes due to the formation of ZnO/PANI heterojunctions in PAN@PANI@ZnO NFs. The obtained PAN@PANI@ZnO photocatalysts are easily recycled with little decrease in photocatalytic activity because of their macroscopic mat structure and flexibility. (C) 2018 Published by Elsevier B.V.