Synthesis and characterization of Cu-Co-Fe hydrotalcites and their calcined products

A series of new Cu-Co-Fe compounds with the general formula Cu Co-x(2-x) Fe1HT (x = 0, 0.5, 1, 1.5 and 2) has been prepared by hydrotalcite coprecipitation method. The presence of hydrotalcite phase is revealed by XRD analysis for x values of 0, 0.5 and 1. When the copper quantity is higher than 1, the malachite phase is preferentially formed. These results are confirmed by TG-DTA, FT-IR and XPS analysis. After calcination at 500 degrees C in air of all samples, XRD analysis reveals the presence of spinel phases such as Co3O4, CoFe2O4, CuFe2O4, Cu xCoyO4 in the solids, monoclinic CuO phase when the copper content is greater or equal to 1 and haematite phase for the sample where x is equal to 2. The presence of these phases is also confirmed by XPS results. For comparison, a Co2Fe1OH sample has been synthesized by classical coprecipitation method and although Co2Fe1HT sample and Co2Fe1OH form a similar phase after calcination at 500 degrees C, Co(2)Fe(1)HT500 presents a higher BET value than Co(2)Fe(1)OH500 sample.