Inorganic fullerene-type WS2 nanoparticles: processing, characterization and its photocatalytic performance on malachite green

Abstract

In this work, we have employed a hydrothermal route for the synthesis of fullerene-type tungsten disulfide (WS2) nanoparticles. X-ray diffraction analysis signifies a hexagonal crystal structure of WS2 with the crystallites experiencing preferred orientations along (002) and (103) planes. The agglomerated nanoparticles and inorganic fullerene (IF)-type structures are apparently observable from the high-resolution electron micrographs. Raman spectrum shows prominent $$ E^{1}_{{2{\text{g}}}} $$ and A 1g modes emanating from the IF nano-WS2 system. The Tauc’s plot obtained from the optical absorption data predicts a direct band gap of ~1.91 eV for the nano-WS2 system; whereas, photoluminescence analysis reveals a broad emission peak located at ~638 nm and is ascribed to the associated transition from the indirect to direct nature of the band gap. The photocatalytic decomposition of malachite green (MG) solution (30 mg/l) by WS2 (100 mg/l) under UV and visible light irradiation has been evaluated. The latter condition exhibited a better photocatalytic response with the MG degradation as high as 71.2%, revealed for 120 min. Photocatalytic and optoelectronic features of IF-type nano-WS2 would bring new insights not only to resolve issues related to environmental hazards, but also in functional devices of technological relevance.