Enhanced photodegradation of Congo red dye under sunlight irradiation by p-n NiFe2O4/TiO2 heterostructure

•NiFe2O4 was prepared by sol gel auto-combustion method using glycine as fuel.•New heterosystem p-NiFe2O4/n-TiO2 was used for Congo red dye degradation under solar irradiation.•The degradation of Congo red (20 mg/L) is quasi total after 180 min.•Kinetic data was well fitted by pseudo-second order model.