A 3D oxalate‐bridged [CuIIFeII] coordination polymer as molecular precursor for CuFe2O4 spinel—photocatalytic features

Abstract

AbstractA 3D heterometallic oxalate‐bridged coordination polymer [CuIIFeII2(H2O)(terpy)(C2O4)3]n (terpy = 2,2′:6′,2″‐terpyridine) (1) was investigated both as photocatalyst for the organic dye removal and as a single‐source precursor for the preparation of the copper ferrite (CuFe2O4) nanocrystals by thermal processing. The dual functionality of 1 was supported by the degradation of aqueous solutions of rhodamine B (RhB) and methylene blue (MB) solutions under visible (Vis) and ultraviolet (UV) light irradiation, powder X‐ray diffraction data collection at room temperature, and the optical and scanning electron microscopy analyses. A close inspection of the X‐ray diffraction patterns unveiled qualitative and quantitative information on the phase composition obtained after the single‐source molecular precursor route to spinel oxide. By optimizing the temperature levels and setting the controlled heating rate at 6 h of holding time, the phase composition of thermal processing of 1 was evaluated—thermal treatment of 1 at 950°C for 6 h and a heating/cooling rate of 10°C min−1 resulted in the formation of solely tetragonal spinel phase of CuFe2O4, whereas the formation of both tetragonal and cubic CuFe2O4 phases was observed at 950°C by the heating rate of 30°C min−1. To obtain the high‐temperature cubic CuFe2O4 oxide, compound 1 was heated and then quenched at 925°C, which led to the formation of the cubic spinel ferrite as the main crystalline oxide phase. Moreover, the photocatalytic properties of the t‐CuFe2O4 spinel were investigated under the same conditions as for 1. The optical bandgap energies were estimated from UV–Vis absorption spectra for both metal oxide and precursor powder.