Nanoscale transformation in CuS Fenton-like catalyst for highly selective and enhanced dye degradation

Abstract

Herein, we have synthesized covellite, copper sulfide nanoparticles (CuS NPs) as an excellent Fenton-like catalyst via facile precipitation method. We studied the structural and compositional changes of CuS Fenton-like catalyst before and after Fenton reaction, in dark and visible light conditions. CuS catalyst exhibited cationic dyes (methylene blue and rhodamine) degradation under dark conditions, whereas under visible light illumination both cationic dyes (methylene blue and rhodamine) and anionic dyes (methyl orange and bromophenol blue) were degraded. Moreover, the degradation rate of both cationic and anionic dyes were enhanced under visible light illumination. XRD, UV–Vis-NIR and XPS spectral studies shown that CuS catalyst through Fenton reaction transformed into Cu2-xS and Cu2S in dark and light conditions, respectively. Studies using reactive oxygen species (ROS) scavengers suggest that hydroxyl radicals are active species for degradation of cationic dyes in dark, whereas superoxide radicals were active species for degradation of anionic dyes in visible light. On one hand, the nanoscale transformation of catalyst facilitated the degradation activity for many cycles, on the other it offered the possibility for selective and enhanced round the clock degradation of dyes