A new solution route for the synthesis of CuFeO2 and Mg-doped CuFeO2 as catalysts for dye degradation and CO2 conversion

Abstract

In this study, CuFeO2 and Mg-doped CuFeO2 powders are synthesized by using a novel chemical solution route under an ambient atmosphere. By regulating the pH of the reaction solution, on the basis of Pourbaix diagrams, and the stoichiometric ratio of copper to iron ions, delafossite CuFeO2 powders are formed at 363 K in an aqueous solution. Mg-doped CuFeO2 powders are also synthesized by using the same chemical route with the trace addition of Mg(II) ions. From the powder X-ray diffraction results, all diffraction peaks are of the delafossite structure with dominated 3R phase and few 2H phase. X-ray photoelectron spectroscopy measurements show that the chemical environments of the Cu and Fe ions are consistent with the binding energies of Cu(I) and Fe(III) in the delafossite structure of CuFeO2. The UV–vis spectra show that the CuFeO2 and Mg-doped CuFeO2 powders are both able to absorb light with wavelengths ranging from 300 to 700 nm. The calculated optical band gaps of the CuFeO2 and Mg-doped CuFeO2 powders are 1.35 and 1.5 eV, respectively. With regard to the application of the powders in the photodegradation of 50 ppm methylene blue, the results suggest that at an incident light irradiation of AM 1.5G, the photodegradation efficiency of the Mg-doped CuFeO2 powder is remarkably better than that of the CuFeO2 powder, which can be attributed to its higher carrier concentration. Furthermore, at an external bias of −1.2 V, these delafossite catalysts are able to convert CO2 to ethylene glycol through an electrocatalytic reaction.