Insights into photocatalytic mechanism for the rational design of p-n heterojunction by decorating mesoporous SnS2 over ZnFe2O4 nanocomposite for accelerated visible light photocatalysis

Binary p-n heterojunction of ZnFe2O4/SnS2 nanocomposite (NCs) was constructed by sonochemical assisted technique for enhanced visible light induced photocatalytic performance. The narrow bandgap of 2.21 eV facilitated the photocatalyst be to active under visible-light irradiation. The rate of photodegradation of methylene blue (MB) dye by optimized-NCs ratio was observed to be remarkable with multifold enhancement than pristine ZnFe2O4 and SnS2. The interfacial contact enforces an internal electric field dependent directional charge migration which hinders charge recombination that was verified by reduced photoluminescence intensity in NCs. The degradation process was found to follow pseudo-first order kinetics. The major ROS involved in the photodegradation process were found to be hydroxyl ((OH)-O-center dot) and superoxide (O-center dot(2)-) radicals which were identified through the scavengers assay. The NCs were subjected to six consecutive cycles in order to test its structural stability and reusability. This work provides guidance for rational design of heterojunction with superior activity and it reflected the potential of ZnFe2O4/SnS2 NCs as a promising photocatalyst to remove toxic pollutants from the aqueous bodies.