Ultra-fast photocatalytic degradation phenomena of methylene blue dye by CoFe2O4 decorated with rGO nanocomposites under visible light irradiation

Abstract

Pollutant water discharged from industries makes serious threat to living beings like humans and animals. Hence, the quick action for cost-effective, eco-friendly, portable, thermally-chemically stable materials meets the high demand for clean water. In the present work, pristine CoFe₂O₄ and series of CoFe₂O₄/rGO (0 to 20 wt%) composite photocatalysts were synthesized by hydrothermal method. The structural, morphological, optical a, porosity and elemental composition of the samples were analyzed by XRD, SEM, TEM, FTIR, UV, PL, BET and XPS analysis. XRD and TEM results suggest that CoFe₂O₄ has cubic stricture and spherical shaped morphology with sizes in the range of 20–30 nm, which is uniformly decorated on the rGO sheets surface. The band gap energy values for the rGO, CoFe₂O₄, and rGO-CoFe₂O₄ nanocomposite were determined to be 2.4 eV, 2.21 eV, and 2.02 eV, respectively. The 20 wt% rGO decorated CoFe2O4 showed high surface area (122 m²/g) and porous nature (12 nm) than compared with pristine CoFe2O4 (88 m²/g and 19 nm). Photoluminescence (PL) results evident the low recombination rate of electron- hole pairs in the nanocomposite samples having 20 wt% of rGO (RC20). The observed gain high efficiency as 96.43 % of cationic dye methylene blue (MB). Whereas the kinetics study revealed that pseudo first-order reaction kinetics to rate constants (K = 0.1675 min⁻¹ and R² is 0.96521). The reusability test of the catalyst reveals 92.06 % degradation after 7 consecutive cycles. Moreover, this review specifically discusses the effects of catalyst's dose, pH, and reaction time on MB removal. Changes are observed on before and after treatment are analyzed by using XRD and FTIR for their physico-chemical properties. Antimicrobial study is evaluated for E. coli and S. aureus bacteria. In this pathway of purifying polluted water removal mechanisms are also elaborated. Therefore, it is found that the incorporated rGO helps to improve the characteristic functionalities of CoFe₂O₄.