Multiwalled carbon nanotube (MWCNT)/Bi4O5Br2 materials have been prepared with the Bi4O5Br2 ultra small nanosheets in situ strong coupling to MWCNT via the ionic liquid (IL) assisted solvothermal method. The formation mechanism was based on the original formation of strong coupling between the IL and MWCNT, and then the tight junctions between Bi4O5Br2 and MWCNT can be established as the bromine ions in the IL react with bismuth source to in situ produce Bi4O5Br2 during solvothermal process. The structures, morphologies, surface features, optical properties, electronic structures and photocatalytic properties were investigated in detail. The MWCNT/Bi4O5Br2 materials exhibited increased photocatalytic activity than pure Bi4O5Br2 for the degradation of antibiotic agent tetracycline hydrochloride and rhodamine B. Meanwhile, the 0.1 wt% MWCNT/Bi4O5Br2 materials displayed the highest activity. The hole and O-2(center dot-) were determined to be the main active species during the photodegradation process under visible light irradiation by the electron spin resonance, X-ray photoelectron spectroscopy valence band spectra and active species trapping experiments. After the introduction of MWCNT, the molecular oxygen activation capacity of Bi4O5Br2 greatly improved, which was believed to be responsible for the increased photocatalytic activity. (C) 2016 Elsevier B.V. All rights reserved.