Facile synthesis of novel Z-scheme GO-modified ternary composite as photocatalyst for enhanced degradation of bisphenol-A under sunlight

Abstract

BackgroundPhotocatalytic degradation using sunlight as a light source has attracted increasing attention because of low operating cost, high degradation efficiency, and environmental friendliness. Metal oxide decorated graphene oxide-based composites as Z-scheme photocatalysts are highly efficient in degrading bisphenol-A (BPA), but such studies are scarce. MethodsThis work employed a facile and green synthesis route for Z-scheme GO-modified ternary composite (ZnO/GO/Mn2O3) photocatalyst. FTIR, FESEM, RAMAN spectra, EDX, BET, XRD, UV–Vis DRS, and PL spectra characterized the synthesized materials. Significant findingsThe results indicate that the catalyst's bandgap energy and surface area were 1.69 eV and 75.35 m2/g. The synthesized ZnO/GO/Mn2O3 composite degrade BPA under sunlight irradiation and completely degraded within 20 min reaction time, pH 7, and using 10 mg/100 mL catalyst dosage. Free radical capturing experiments established that the dominant reactive species for degradation were •O2− and h+ having 95.16 and 91.23% degradation efficiency. The kinetic study show that the pseudo-first-order best presents the kinetic model, and the rate constant (0.201 min−1) was 22.22, 14.28, and 4.08 times higher than Mn2O3, GO, and ZnO/GO, respectively. The enhanced catalytic activity occurred due to the development of an efficient Z-scheme heterojunction, which facilitates the separation of charge carriers, thereby increasing the number of reactive species in the solution. The recycling experiments showed only 10.85% degradation was reduced after five consecutive cycles. Finally, a plausible BPA degradation mechanism was proposed.