A novel method of water remediation of organic pollutants and industrial wastes by solution-route processed CZTS nanocrystals

CZTS (Cu2ZnSnS4), a P-type semiconductor with a direct bandgap (1.2-1.7eV), earth-abundant, non-toxic, and has a large absorption coefficient makes it extremely useful in optoelectronics and light-harvesting applications. In this work, CZTS is prepared by an ingenious, cost-effective colloidal route using the 'hot-injection' method with the usage of different ligands. The XRD and Raman spectroscopy shows the single-phase highly crystalline CZTS nanoparticles with kesterite structure. The TEM results show that the size of CZTS nanoparticles is about 2-5 nm and monodispersity is confirmed by DLS (Dynamic Light Scattering). FTIR confirms the presence of different ligands used in CZTS preparation. The Uv-vis absorption shows the direct bandgap of 1.5-1.7eV. The contact angle study shows the hydrophobic nature of as-synthesized CZTS nanoparticles which were further ligand exchanged with L-cysteine hydrochloride to make it hydrophilic to study the photocatalytic degradation activity of organic pollutants and industrial waste in the water. The photocatalysis experiments were performed under two conditions: (i) under bare sunlight (Intensity similar to 900 W/m(2)) (ii) focussing the sample under the sunlight via converging lens (1800 W/m(2)). The photocatalytic efficiencies were then compared and the best photocatalytic efficiency achieved under sunlight was 98.4% for organic pollutants and 75% for industrial waste via converging lens while the corresponding efficiencies with bare sunlight were 98.1% and 73% respectively. To the best of the author's knowledge, a rapid and highly efficient photocatalysis of CZTS NPs employing a converging lens for water-remediation without the usage of noble & transition-metals has been reported for the first time. (C) 2021 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Automated summary

CZTS, a P-type semiconductor with a direct bandgap, is prepared by a cost-effective colloidal route using the 'hot-injection' method. It exhibits single-phase highly crystalline structure with monodisperse nanoparticles of 2-5 nm size. CZTS shows excellent photocatalytic degradation activity for organic pollutants and industrial waste in water.