Facile fabrication of AgFe1-xCuxO2 composite with abundant oxygen vacancies for boosted photocatalytic Cr (VI) reduction and organic pollutants degradation under visible light

In order to enhance the utilization of visible light and improve photocatalytic performance of AgFeO2, in this work, a novel copper (Cu) doped AgFeO2 composite catalysts with abundant oxygen vacancies (OVs) were synthesized by the co-precipitation method. The results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) showed Cu was successfully doped in AgFeO2 to form lattice defects, resulting in a large number of oxygen vacancies, which is beneficial for oxygen molecules to be activated into superoxide radicals. Compared with pure AgFeO2, the Cu doped samples expand the absorption region of visible light, thereby enhancing photocatalytic activity in the oxidization of organic pollutants and the reduction of Cr (VI). In a mixed Cr (VI)/Acid Red G (ARG) solution, the 20 mg/L of ARG could be almost completely degraded within 90 min by Cu doped AgFeO2 composite, while the reduction efficiency of Cr (VI) is up to 90.19%, which is 1.95 times higher than that of AgFeO2. After the fourth photocatalytic recycling experiment, the photocatalytic performance of Cu doped AgFeO2 composite is still superior. The results of scavenger experiments show that holes (h(+)) and superoxide anions (O-2(center dot-)) were the main dominant reactive for promoting photocatalytic reduction of Cr (VI) and degradation of organic pollutants over the Cu doped AgFeO2 composites. Based on the results of photoluminescence spectra (PL) and electron spin resonance (ESR), the enhanced photocatalytic performance of the Cu doped AgFeO2 could be contributed to oxygen vacancy caused by doping defects and the enhancement of visible light absorption.

Automated summary

In this study, a novel Cu-doped AgFeO2 composite catalyst with abundant oxygen vacancies was synthesized to enhance visible light utilization and improve photocatalytic performance. The introduction of lattice defects by Cu doping increased the number of oxygen vacancies, leading to enhanced activation of oxygen molecules and expansion of visible light absorption region. The Cu-doped AgFeO2 composite showed superior photocatalytic activity in the oxidation of organic pollutants and reduction of Cr (VI), attributed to the promotion of oxygen vacancy-mediated reactions and enhanced visible light absorption.