Microwave mediated synthesis of dopamine functionalized copper sulphide nanoparticles: An effective catalyst for visible light driven degradation of methlyene blue dye.

The current work highlights the potential aptitude of copper sulphide (CuS) nanoparticles as cost and energy-effective photo-catalyst for degrading methlyene blue dye under visible light. The surface modified CuS nanoparticles with dopamine (DOP) were prepared by using fast and cost effective microwave assisted methodology. Here, DOP act as biological ligand for the reduction and capping of CuS nanoparticles. The structural and morphological analyses revealed the size controlled synthesis of CuS in presence of DOP with higher thermal stability. The bio-compatibility and non-toxic behaviour of CuS@DOP nanoparticles was evaluated against L929 cell lines and on E. coli and S. aureus strains. The visible light driven photocatalytic activity of the synthesized CuS@DOP was scrutinized for the degradation of methylene blue (MB) dyes, as a model of water contaminants. The photocatalytic degradation of MB by CuS@DOP attained 97% after 10 min of visible light irradiation. The effect of catalyst dose, pH, initial concentration of MB dye, electrolytes, contact time, synergic effect of photolysis and catalysis were studied in detail for optimizing the degradation efficiency of CuS@DOP. The mechanism of CuS@DOP photocatalysis and the formed degraded products were analyzed by using LC/MS technique. The reusability and stability of photocatalyst was confirmed by reusing the catalyst for six successive runs with catalytic performance as high as 80%. Thus, CuS@DOP NPs acted as cost effective, non-toxic visible light driven photo-catalyst for the degradation of organic dye from waste water.