Enhancing photodecomposition of cationic organic dyes of rhodamine and methylene blue employing the Ta2O5–CdS composite driven by visible light irradiation

Abstract

The Ta2O5–CdS composites with the various ratios of Ta2O5/CdS were synthesized to study their employment in the photodecomposition of RhB (rhodamine B)/MB (methylene blue). The samples characterized by XRD, FESEM, EDS, and TEM proved the formation of the Ta2O5–CdS with cauliflower morphology. According to DRS analysis, Ta2O5–CdS exhibited redshifts, and their band-gaps (2.00 eV and 2.10 eV for Ta2O5/CdS = 1 and 3) decreased in contrast to pure CdS (2.18 eV). The BET-specific surface areas (9.221 m2/g) of the Ta2O5–CdS composite (Ta2O5/CdS = 1) measured by N2 adsorption-desorption isotherms were enhanced in contrast to pure CdS (1.817 m2/g). Moreover, MB photodecomposition by Ta2O5–CdS with the weight ratios of Ta2O5/CdS = 3 and 1 improved to 90% and 99%, respectively, in contrast to pure CdS (80%). Besides, the Ta2O5–CdS composite (Ta2O5/CdS = 1) exhibited the highest RhB decomposition (97%). Hence, for the first time, this study has surveyed the photodecomposition of the cationic dyes by the Ta2O5–CdS with excellent photocatalytic performance. The role of active species was detected through species quenching tests. A reliable mechanism was suggested to reveal how the RhB/MB decomposition was promoted compared to CdS. The photodecomposition results corresponded to the pseudo first order kinetic model.