Regular Article Novel 2D/2D g-C 3 N 4 /Bi 4 NbO 8 Cl nano-composite for enhanced photocatalytic degradation of oxytetracycline under visible LED light irradiation Ankush Majumdar, Utpal Ghosh, Anjali Pal ⇑ Department of Civil Engineering, Indian Institute of Technology, Kharagpur 721302, India highlights  Novel 2D/2D g-C 3 N 4 /Bi 4 NbO 8 Cl nano- composites were hydrothermally synthesized.  Photocatalytic degradation of oxytetracycline under visible LED light was improved.  The formed g-C 3 N 4 /Bi 4 NbO 8 Cl heterojunction enhanced the photocatalytic activity.  Possible photocatalytic oxytetracycline degradation mechanism was proposed. graphical abstract article info Article history: Received 16 May 2020 Revised 23 September 2020 Accepted 25 September 2020 Available online 6 October 2020 Keywords: g-C 3 N 4 /Bi 4 NbO 8 Cl Type-II heterojunction 2D/2D nano-composite Visible-light photocatalyst Oxytetracycline degradation abstract A novel visible-light-responsive 2D/2D g-C 3 N 4 /Bi 4 NbO 8 Cl nano-composite photocatalyst was hydrother- mally synthesized using g-C 3 N 4 and Bi 4 NbO 8 Cl. Various characterization techniques were employed to characterize the as-synthesized g-C 3 N 4 /Bi 4 NbO 8 Cl nano-composites. The photocatalytic efficiency of the nano-composite materials was assessed by the degradation of an emerging pharmaceutical pollutant, oxytetracycline (OTC), under visible LED light irradiation. It was observed that at an optimum mass ratio of 20% (g-C 3 N 4 to Bi 4 NbO 8 Cl), the 20g-C 3 N 4 /Bi 4 NbO 8 Cl nano-composite produced the highest photocat- alytic degradation efficiency toward OTC. The photocatalytic degradation of OTC (20 mgL 1 ) by 20g- C 3 N 4 /Bi 4 NbO 8 Cl (1 gL 1 ), under 60 min of visible LED light irradiation was 87%, which was about 1.2 and 1.8 times higher as compared to that of pure Bi 4 NbO 8 Cl and g-C 3 N 4 , respectively. This improved per- formance was associated with the formation of type-II heterojunction, which resulted in better visible- light absorption and reduced recombination of photogenerated electron-hole pairs. Moreover, it was observed that after four cycles of degradation experiments, the nano-composite was stable. The results of this work not only demonstrate the construction of 2D/2D g-C 3 N 4 /Bi 4 NbO 8 Cl nano-composite for suc- cessful low-cost and energy-efficient photocatalytic degradation of recalcitrant pollutant but also moti- vate the production of similar photocatalysts targeting environmental remediation. Ó 2020 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jcis.2020.09.101 0021-9797/Ó 2020 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: Department of Civil Engineering, Indian Institute of Technology, Kharagpur 721302, India. E-mail address: anjalipal@civil.iitkgp.ac.in (A. Pal). Journal of Colloid and Interface Science 584 (2021) 320–331 Contents lists available at ScienceDirect Journal of Colloid and Interface Science journal homepage: www.elsevier.com/locate/jcis