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

Background: Photocatalytic 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. Methods: This 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 findings: The results indicate that the catalyst's bandgap energy and surface area were 1.69 eV and 75.35 m(2)/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 O-center dot(2)- 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.

Automated summary

In this study, a green and facile method was used to synthesize a Z-scheme graphene oxide-modified ternary composite (ZnO/GO/Mn2O3) photocatalyst. Characterization results showed that the catalyst had a bandgap energy of 1.69 eV and a surface area of 75.35 m2/g. The synthesized ZnO/GO/Mn2O3 composite exhibited efficient degradation of BPA under sunlight irradiation, with complete degradation achieved within 20 minutes. The enhanced catalytic activity was attributed to the formation of an efficient Z-scheme heterojunction, which facilitated the separation of charge carriers and increased the number of reactive species in the solution. The catalyst also showed good recyclability, with only a slight reduction in degradation efficiency after five consecutive cycles.