Addition of g-C3N4 to ZnO and ZnFe2O4 to improve photocatalytic degradation of emerging organic pollutants

Abstract

The use of heterojunctions with different semiconductors has shown to be an important strategy to increase the efficiency of heterogeneous photocatalytic processes. In this regard, heterojunctions consisting of ZnO/g-C3N4 (x-Zn/gCN) and ZnFe2O4/g-C3N4 (x-ZF/gCN) were synthesized in different mass proportions of g-C3N4 (x = 10, 50 and 80%) through the following simple methods combination: mixture, sonication and thermal treatment. Observations from X-ray diffractometry (XRD), Fourier-transform infrared spectra (FTIR) and field emission scanning electron microscope (FESEM) analyses confirmed that the materials were successfully formed. The g-C3N4 incorporation was important in the textural and optical properties modification of the heterojunctions produced. In addition, in the photoluminescence spectroscopy (PL), it was possible to observe g-C3N4 influence in the 50-Zn/gCN emission profile changing, reducing the direct recombination rate of the photogenerated charges due to a probable Z-scheme mechanism. This catalyst demonstrated greater efficiency of photocatalytic degradation when compared to the remaining materials, both for cefazolin (CFZ) and reactive black 5 (RB5), reaching 78% and 95%, respectively, after 120 min. Moreover, it also revealed good photostability after five successive cycles. 50-Zn/gCN heterojunction presents a promising character in photocatalytic reactions mediated by solar light for contaminants degradation such as pharmaceutical products and dyes and can be used as an alternative to minimize the effects of water pollution caused during the COVID-19 pandemic.