An outstanding, efficient visible-light-driven BiOI/LaCoO3 Z-scheme system toward cefixime degradation†

Abstract

Multiple pollutants, especially antibiotics, are polluting water systems, prompting the development of novel photocatalysts with synergistic activity for mineralizing these pollutants. In this study, we synthesized three-dimensional BiOI microspheres, supported by noble metal-free LaCoO₃ co-catalysts, to construct an enhanced hybrid photocatalyst featuring superior charge separation properties. Various techniques were used to characterize the samples, including FTIR, SEM-EDX, XRD, and UV-Vis DRS (diffuse reflectance spectroscopy). Based on the Williamson–Hall equation, the BiOI/LaCoO₃ sample had an average crystallite size of 50.70 nm. BiOI, LaCoO₃, and BiOI/LaCoO₃ have band gaps of 1.80, 1.56, and 1.57 eV, relating to absorption edge wavelengths of 684, 790, and 789, respectively. For BiOI, LaCoO₃, and BiOI/LaCoO₃, the pHpzc (point of zero charge pH) values were 5.8, 10.5, and 8.9, respectively. In this coupled system, the moles of LaCoO₃ oxide are four times greater than those of another component, resulting in boosted activity. According to the response surface methodology (RSM) study, the suggested model shows a F-value of 50.26 > F_0.05,14,15 in the model, as well as a LOF F-value of 3.44 < F_0.05,10,5 and high R²-values (R² = 0.9908, pred-R² = 0.9989, and adj-R² = 0.9996). The proposed binary catalyst of BiOI/LaCoO₃, the direct Z-scheme, is the preferred method of illustrating Cefixime photodegradation. Using chemical oxygen demand (COD) data, we could derive the rate constants of 0.053 min⁻¹ and 0.061 min⁻¹ for photodegrading solutions. During photodegradation, CEF molecules degrade at a t_1/2 of 13.07 and mineralize at a t_1/2 of 11.36.