Effect of Copper Doping Over GdFeO3 Perovskite on Soot Oxidation Activity

A series of Fe substituted (B-site doping) by Cu on the GdFeO3 perovskite materials (GdFe(1-x)CuxO(3 +/-delta), x = 0 to 0.3) were synthesized using EDTA-Citrate method. The effect of Cu loading on the physio-chemical investigations of the obtained samples was carried out using X-ray Diffraction technique, BET surface area analysis, FESEM/EDS, TEM analysis, XPS, -H-2-TPR, and Soot-TPR. The performance of perovskites towards soot oxidation was analyzed in detail using TGA equipment. The results of the XRD pattern shows that upto10 mol% of Cu doping was dissolved into the lattice of GdFeO3. H-2-TPR results reveal that the samples with Cu loading exhibit the successive reductions of Cu2+, Fe3+, and Fe2+ which implies the presence of multiple oxidation states in the perovskite. This induces the oxygen vacancies in the doped samples (due to charge compensation) leading to an increase in soot oxidation activity. According to the XPS results it was observed that the surface composition of Gd is in +3, Fe in +2 and +3 and Cu in + 2 oxidation states. Moreover, the O1s peaks of the doped samples clearly evidenced an increase in adsorbed oxygen species when compared to the un-doped one. Among the doped samples, 10 mol% of Cu loading in -GdFeO3 showed the higher activity of oxygen species. The T-50% (temperature at 50% conversions) of the samples was in the order of GFCu30% < GFCu10% < GFCu5% < GFCu15% < GdFeO3 < bare soot.