Synergistic design of a graphene oxide-mediated polyaniline/α-Fe2O3 ternary heterostructure: advancing photocatalytic degradation and adsorption efficiency†

Abstract

With the growing threat of organic pollutants in water bodies, there is an urgent need for sustainable and efficient water decontamination methods. This research focused on synthesizing a novel Z-scheme ternary heterostructure composed of graphene oxide (GO)-mediated polyaniline (PANI) with α-Fe₂O₃ and investigated its potential in brilliant green (BrG) and ciprofloxacin (CIP) degradation tests under visible light. The ternary composite demonstrated exceptional photocatalytic activity, with the optimized 10%PANI/GO/α-Fe₂O₃ (10PGF) photocatalyst achieving 99.8% degradation of BrG in 25 min and 93% degradation of CIP in 90 min of irradiation. The 10PGF composite achieved rate constants of 0.222 min⁻¹ for BrG and 0.0295 min⁻¹ for CIP. The rate constant for BrG degradation was 15 and 10 times faster than that for PANI and α-Fe₂O₃, respectively, while CIP was degraded 8.9 and 6.1 times faster. The degradation of the pollutants was facilitated by both O₂˙⁻ and ˙OH, as confirmed by capturing active species, a nitroblue tetrazolium test and use of a PL terephthalic acid probe. The proposed Z-scheme mechanism elucidated charge carrier movements and active species involvement, revealing the enhanced photocatalytic performance of the ternary composite. The 10PGF ternary composite demonstrated exceptional recyclability over five repeated cycles, with XRD analysis confirming no structural changes in the material. Moreover, adsorption studies were also performed, which showed a strong correlation (R² = 0.974) with Langmuir isotherms and that pseudo-second order kinetics was followed.