The untreated effluent dropping into the environment from various textile industries is a major issue. To solve this problem, development of an efficient catalyst for the degradation of macro dye molecules has attracted extensive attention. This work is mainly focused on the synthesis of nickel–manganese sulfide decorated with rGO nanocomposite (Ni–Mn-S/rGO) as an effective visible photocatalyst for degradation of textile toxic macro molecule dye. A simple hydrothermal method was used to synthesize Ni–Mn-S wrapped with rGO. The prepared composites were characterized using various techniques such as X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectrometer (FTIR), and ultra violet–visible (UV–Vis) spectroscopy. The photocatalytic performance of nickel sulfide (NiS), manganese sulfide (MnS), nickel–manganese sulfide (Ni–Mn-S), and Ni–Mn-S/rGO nanocomposite was assessed by analyzing the removal of acid yellow (AY) and rose bengal (RB) dyes under natural sun light. Among these, the Ni–Mn-S/rGO nanocomposite showed the high photocatalytic degradation efficiency of AY and RB dyes (20 ppm concentration) with efficiency at 96.1 and 93.2%, respectively, within 150-min natural sunlight irradiation. The stability of photocatalyst was confirmed by cycle test; it showed stable degradation efficiency even after five cycles. This work confirms that it is an efficient approach for the dye degradation of textile dyes using sulfide-based Ni–Mn-S/rGO nanocomposite.

Synthesis of nickel–manganese sulfide decorated with reduced graphene oxide nanocomposite for ultra-fast photocatalytic degradation of organic dye molecules
    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Materials
        2.2 Preparation of Ni–Mn-SrGO
        2.3 Characterization
        2.4 Photocatalytic degradation of textile dye
    3 Results and discussion
        3.1 Structural analysis
        3.2 Functional groups analysis
        3.3 Morphological analysis
        3.4 Optical analysis
        3.5 Photocatalytic degradation of dyes
            3.5.1 Reusability studies
    4 Conclusions
    Acknowledgements 
    References

• Narthana Kandhasamy(Centre for Nanoscience and Nanotechnology, Sathyabama Institute of Science and Technology, Tamil Nadu, Chennai 600 119, India)
• Govindhasamy Murugadoss(Centre for Nanoscience and Nanotechnology, Sathyabama Institute of Science and Technology, Tamil Nadu, Chennai 600 119, India) Corresponding author
• Thiruppathi Kannappan(Department of Physics, SRM Valliammai Engineering College, SRM Nagar, Kattankulathur 603203, Tamil Nadu, India)
• Kamalan Kirubaharan(Coating Department, Fun Glass ‑ Centre for Functional and Surface Functionalised Glass, Alexander Dubcek University of Trencin, 91150 Trencin, Slovakia)
• Rajesh Kumar Manavalan(Institute of Natural Science and Mathematics, Ural Federal University, 620002 Yekaterinburg, Russia)
• Sandhanasamy Devanesan(Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, 11451 Riyadh, Saudi Arabia)
• Mohamad S. AlSalhi(Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, 11451 Riyadh, Saudi Arabia)
• R. Mythili(Department of Pharmacology, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai 600077, India)
• Surendra Shinde(Department of Physics, Arts, Science and Commerce College, Indapur, Pune, India)
• Hemraj M. Yadav(School of Nanoscience and Biotechnology, Shivaji University, Kolhapur 416004, Maharashtra, India)