Fusion of heterogeneous photocatalysts with conducting polymers has paid a rising stratagem in the field of photocatalysis owing to its biocompatibility and environment friendliness. In this work a series of polypyrrole (PPY) sensitized zinc ferrite/graphitic carbon nitride (ZFCN) n-n heterojunction (ZFCN@10PPY, ZFCN@20PPY, and ZFCN@30PPY) nanocomposite were fabricated by in-situ polymerization method. Due to low band gap of polypyrrole, it behaves as a photo-sensitizer, supplies surplus numbers of electrons to ZnFe2O4/gC(3)N(4) n-n heterojunction and improves the photocatalytic performance. The fabricated ZFCN@20PPY exhibits highest photocatalytic activity in comparison to others nanocomposites. The superior photocatalytic performance of ZFCN@20PPY was ascribed to the tunable band structure, synergistic effect of broad absorption upto NIR region, delayed electron-hole recombination and efficient charge transfer across the junction interface which has been well confirmed from UV-Vis DRS, PL and EIS measurement. Further the photocatalytic activity of ZFCN@20PPY was supported by both n-type and p-type photocurrent density i.e. 2.4 and 3.9 mA/cm(2) respectively. ZFCN@20PPY shows good photocatalytic performance towards ciprofloxacin degradation (92%) and generation of hydrogen energy (567 mu mol). Along with pollutant degradation and energy production ZFCN@20PPY also shows its potential towards antibacterial activities against human pathogenic bacteria like Escherichia coli. These newly designed polymer sensitized n-n heterojunction may offer a promising strategy for maximum light absorption and be authoritative in meeting the environmental claims in the future. (C) 2019 Elsevier Inc. All rights reserved.