Nanostructured hexagonal S-doped CeO2 for effective Rh-B and MB dye degradation

Abstract

The photocatalytic efficiency of CeO_2−xS_x (x = 0.05, 0.1, 0.2, 0.3, 0.5) hexagonal nanoparticles (HNPs) prepared through the hydrothermal method were tested by performing the degradation of Rhodamine-B and Methylene blue dyes under UV light irradiation. These compounds were thoroughly characterised using XRD, FESEM, EDX, HRTEM, XPS, ESR, FTIR, Raman, UV–vis DRS, BET and PL techniques. XRD analysis verified the cubic crystal structure of S-doped and pure CeO₂ HNPs. HRTEM images clearly affirmed that S-doped CeO₂ is made from HNPs. Over 94 % of Rh-B and 72 % of MB dyes were degraded by S-doped CeO₂ for 180 min under UV light exposure, demonstrating its efficacy towards the photocatalytic activity (PCA). S-doped CeO₂ HNPs have enhanced the PCA due to the reduction in the recombination rate of photo-generated electron-hole pairs, the rise in oxygen vacancy (O_v) and the narrowed optical band-gap. The photoluminescence findings clearly validated the increased PCA of S-doped CeO₂. The scavenger tests confirmed the OH^• and ^•O₂⁻ radicals participation in the quick degradation of both Rh-B and MB dyes.