Synthesis and characterization of ternary NiO@Bi2MoO6–MoS heterojunction with enhanced photodegradation efficiency towards indigo carmine dye

Heterojunctions and metal oxide dopants are commonly used in binary and ternary nanocomposites to enhance photo degradability and maintain metal-free properties. This work describes the preparation of a novel NiO@Bi2MoO6–MoS complex ternary heterostructure using a simple solvothermal technique that possesses excellent photo activities for the removal of toxic Indigo carmine (InCa) dye from wastewater using a visible-illumination source. The prepared composites were characterized using various physicochemical techniques such as UV–Visible spectra, X-ray diffraction (XRD) techniques, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transforms infrared (FTIR) spectroscopy, elemental disperse X-ray (EDX) analysis, BET surface area, photoluminescence (PL), electron spin resonance (ESR) spectroscopy, and LC-MS analysis. The UV–Visible spectrophotometer confirmed that the absorption performance of the ternary NiO@Bi2MoO6–MoS composite is comprehensive in the visible light regions. NiO@Bi2MoO6–MoS exhibited the characteristic diffraction peaks of NiO and Bi2MoO6–MoS with a band gap energy (Eg) of 3.03 eV. SEM images confirmed that the synthesized composites show good phase confirmation, with particle sizes of ∼25 nm and morphologies of nanoflakes (Bi2MoO6–MoS) and nanorods (NiO@Bi2MoO6–MoS). The PL intensity of NiO@Bi2MoO6–MoS is much lower than that of Bi2MoO6 and Bi2MoO6–MoS composites, indicating a much more effective separation of photo-generated electrons and holes at the interface which in turn leads to the expected photocatalytic performance. The photocatalytic activity results showed that the degradation efficiency of NiO@Bi2MoO6–MoS for InCa dyes was 98.8%within 120 min, which is significantly superior to the binary composite Bi2MoO6–MoS (73.2%).The enhanced photo degradability of NiO@Bi2MoO6–MoSis a result of the hierarchical superstructure, enhanced visible light absorption, efficient charge transfer, and synergistic interaction between NiO, MoS, and Bi2MoO6 nanoparticles. Synergistic adsorption, effective double Z-scheme, and S-scheme mechanisms were efficient for the degradation of InCa dye into CO2, H2O, inorganic ions, and simpler products that showed excellent recyclability over five consecutive cycles.