Bismuth dichalcogenide-exfoliated Bi2Se3 nanosheets: A novel approach for hexavalent chromium and azo compound photocatalysis

A promising approach for the photocatalytic degradation of hexavalent chromium [Cr(VI)] and azo compounds in wastewater involves utilizing exfoliated nanosheets derived from bismuth dichalcogenide crystals, specifically Bi2Se3. In this study, we synthesized Bi2Se3 nanosheets through a straightforward sonication method using N, N-Dimethylformamide as the solvent. The resulting Bi2Se3 nanosheets displayed substantial surface areas, layered sheet structures resembling rocks, and exhibited single crystalline characteristics, featuring an optical bandgap of 5.30 eV and a lattice spacing of 0.505 nm. Photocatalytic assessments employing methyl orange (MO) and Cr(VI) as model pollutants demonstrated remarkable efficiency, achieving degradation rates of up to 81.2% within 240 min and 88.4% within 60 min, respectively, under visible light exposure. Both reactions adhered to pseudo-first-order kinetics, with kinetic constants (k) of 0.0038 min−1 for MO and 0.007 min−1 for Cr(VI). The underlying photocatalytic mechanism involved the transfer of electrons from the Bi2Se3 nanosheets to the pollutants adsorbed on their surface, resulting in the efficient detoxification of wastewater. This investigation underscores the potential of exfoliated Bi2Se3 nanosheets as exceptionally effective and environmentally sustainable photocatalysts for the remediation of wastewater contaminated with Cr(VI) and MO, making significant contributions to the field of environmental remediation. This research not only provides insights into the novel utilization of Bi2Se3 nanosheets but also addresses urgent environmental issues, indicating its potential significance in promoting sustainable wastewater treatment methods.