Controlled shape and size with tuneable band gap (1.92–2.41 eV), nickel sulphide NPs was achieved in presence of thiourea or thioacetamide as sulphur sources with the variations of temperature and capping agents. Synthesized NPs were fully characterized by powder XRD, IR, UV-vis, DRS, FE-SEM, TEM, EDX, XPS, TGA and BET. Capping agent, temperature and sulphur sources have significant role in controlling the band gaps, morphology and surface area of NPs. The catalytic activities of NPs were tested for round the clock (light and dark) decomposition of crystal violet (CV), rhodamine B (RhB), methylene blue (MB), nile blue (NB) and eriochrome black T (EBT). Agitation speed, temperature, pH and ionic strength have significant role on its catalytic activities. The catalyst was found to generate reactive oxygen species (ROS) both in presence and absence of light which is responsible for the decomposition of dyes into small fractions, identified with ESI-mass spectra.

5Ag-In-Ni-S nanocomposites of different shapes were productively achieved in water using thioacetamide at different temperatures in presence of SDS with uniform size distributions. It was found that variation of SDS and temperature had significant influence on morphology of Ag-In-Ni-S and their photocatalytic activity. The newly synthesized Ag-In-Ni-S nanocomposites were fully characterized by powder XRD, IR, UV-Vis, DRS, FE-SEM, TEM, EDX, XPS, BET and TGA. The catalytic activities were measured by 10 the degradation of methylene blue (MB) in absence and presence of visible light (sunlight, 100W tungsten lamp). The catalyst was found effective in degrading MB through generation of ROS that was confirmed using TA, DHR123 treatment and ESI mass spectroscopy. Removal efficiency of MB by the nanocomposites is very fast, nearly quantitative and repetitive upto five cycles. 75 2. Experimental 2.1 Material Silver acetate dihydrate [Ag(OAc)•2H 2 O], Indium acetate

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