Abstract
A ternary arrow down dual S-scheme nano photocatalyst ZnIn2S4/Bi2O2CO3/ZnFe2O4 composed of microspheres of ZnIn2S4, layered Bi2O2CO3, and magnetic ZnFe2O4 has been prepared for RhB degradation. The ZnIn2S4/Bi2O2CO3/ZnFe2O4 degraded 99.8% of RhB in 90 min, and its photocatalytic activity toward RhB degradation was highest as compared to pure ZnIn2S4 (36.38%), Bi2O2CO3 (19.56%), ZnFe2O4 (16.65%) and binary Bi2O2CO3/ZnFe2O4 (43.82%) composite. The Langmuir-Hinshelwood kinetics model was found for RhB degradation for all photocatalysts. The rate constant of the ZnIn2S4/Bi2O2CO3/ZnFe2O4 hybrid photocatalyst was 0.177 min(-1), which is 12.73, 29.84, and 38.06 times greater than pure ZnIn2S4, Bi2O2CO3, and ZnFe2O4, respectively. UV-Vis, EIS, and PL measurements indicate that the synergistic effect is brought on by an expanded range of light absorption, lower charge separation resistance, and decreased recombination of e(-)/h(+) pairs. The significant decrease in photocatalytic activity with radical scavengers established that O-center dot(2)-, (OH)-O-center dot, and h(+) were the active free radicals, and O-center dot(2)- was the leading one during the degradation of RhB. The dual S-scheme electron transfer mechanism has been proposed because lesser energy electrons and holes were destroyed, and charge carriers with higher redox potentials were retained. The photocatalysts' good magnetic separation and photostability were confirmed after four reuse cycles and maintained 87% degradation efficiency.