Synthesis of novel nanocomposite of g-CN coated ZnO-MoS for energy storage and photocatalytic applications.

Fabrication of heterostructures for energy storage and environmental remedial applications is an interesting subject of research that has been undertaken in this present investigation. The incorporation of g-CN into ZnO:MoS heterojunction nanocomposite was accomplished by wet-chemical route and characterized by various techniques to ascertain its structure, morphology, and study its potential electro-optical characteristics. The g-CN@ZnO:MoS sample was investigated by x-ray diffraction (XRD) which reveals the co-existence of the ZnO, MoS and CN phases linked to characteristic crystallographic planes in the spectrum, validating the formation of ternary nanocomposite. The XRD patterns of the pristine samples were also considered as reference to understand the structural evolution and phase transformations. Field emission scanning electron microscopy (FESEM) study states the formation of heterogeneous nanostructures having nanoparticles embedded on 2-D nanosheets like structures. Studies using energy dispersive spectroscopy (EDS) and elemental mapping show that all the elements that are linked to the above hybrid nanocomposite are present. Transmission electron microscopy (TEM) provided clear insights on the microstructure as we can identify the distribution of ZnO and MoS nanostructures on layered g-CN nanosheets. The chemical composition and oxidation states of elements were elucidated by X-ray photoelectron spectroscopy (XPS) study, which added another layer of confirmation on the structural evolution of the ternary nanocomposite. Fourier transformed infrared (FTIR) study revealed the layered structure of sp hybridized bonding features of C and N in g-CN, besides Zn-O and Mo-S stretching vibrations. The nanocomposite demonstrated improved photodegradation efficacy and decomposed alizarin red and methylene blue dyes significantly with better stability and reusability. MoS as a co-catalyst acts as an electron acceptor/accelerator in the Z-scheme composite photocatalysis leading to improved photocatalytic efficiency. The resulting heterostructured material delivered a higher specific capacitance of 10.85 F/g with good capacitance retention. Electrochemical study revealed the energy storage capability of the hybrid system.