Visible light driven g-C3N4/Bi4NbO8X (XCl, Br) heterojunction photocatalyst for the degradation of organic pollutants

A highly potential visible light active g-C 3 N 4 /Bi 4 NbO 8 X (Cl, Br) heterojunction photocatalysts were constructed at the interface of the coupling between Bi 4 NbO 8 X (Cl, Br) and g-C 3 N 4 . The band gap value of heterojunctions g-C 3 N 4 /Bi 4 NbO 8 Br-20% (CNBNB-3), g-C 3 N 4 /Bi 4 NbO 8 Cl-20% (CNBNC-3), and pristine materials g-C 3 N 4 (CN), Bi 4 NbO 8 Cl and Bi 4 NbO 8 Br were analyzed to be 2.68 eV, 2.69 eV and 2.74 eV, 2.46 eV and 2.48 eV, respectively. The degradation performance of optimized CNBNC-3 and CNBNB-3 photocatalysts revealed much superior removal efficiency of 97% and 84% than the pristine material for rhodamine B. The synthesized photocatalysts maintained good recyclable stability after five consecutive cycles and potentially capable of pollutant degradation. The electrochemical impedance and photoluminescence spectroscopy revealed that the migration and separation efficiency of photogenerated charge carriers of photocatalyst were boosted, while reduced recombination rate was observed. The photocatalytic reaction mechanism also revealed the superoxide ·O 2 − and • OH radicals are the main active species responsible for the pollutant degradation.