Controlled Synthesis Approaches for Tuning the Structural, Optical, and Morphological Features of Chemo-catalytically Active Covellite (CuS) Nanostructures

Covellite (CuS) nanostructures were meticulously engineered using chemical precipitation, mechanochemical, and hydrothermal methods, with copper chloride and thiourea as key precursors. The influence of each synthesis route on the structural, optical, and morphological properties was systematically explored through comprehensive characterization techniques, including XRD, EDS, FESEM, HR-TEM with SAED, BET, UV–VIS, FT-IR, and Raman spectroscopy. The results unveiled striking morphological variations, where flake- and sheet-like CuS nanoparticles self-assembled into distinct architectures—cuboids, microflowers, or staircase-like formations—demonstrating the pivotal role of synthesis conditions in shaping their structure. Growth mechanisms were analyzed for each method, and their chemocatalytic efficiency in methylene blue (MB) dye degradation was critically evaluated. The reaction mechanism for chemocatalytic dye degradation was investigated, and kinetic analysis demonstrated that it adheres to pseudo-first-order kinetics as described by the Langmuir–Hinshelwood model. Notably, the mechanochemical approach emerged as a promising strategy for enhancing catalytic activity, underscoring the significance of synthesis optimization in advancing CuS-based materials for sustainable environmental remediation.