The cobalt-ferrite, CoxFe3−xO4, activity in the catalytic chemical decomposition op hydrogen peroxide

Structure–activity correlation in aerobic cyclohexene oxidation and peroxide decomposition over CoxFe3−xO4 spinel oxides

“…Cota et al 43 and Goldstein et al , 44 who both had a leading role in the research on peroxide decomposition in the last century, prepared CoFe 2 O 4 samples enabling surface-area-normalized rate constants of k s = 0.071 s −1 m −2 and k s = 0.120 s −1 m −2 in alkaline solution, respectively, which are significantly lower compared with our catalyst ( k s = 0.527 s −1 m −2 ). Onuchukwu et al 45 also studied H 2 O 2 decomposition in alkaline solution over CoFe 2 O 4 synthesized by co-precipitation and obtained a mass-normalized rate constant of k m = 14 s −1 g −1 , which is one fifth of the spray-flame synthesized CoFe 2 O 4 ( k m = 67.9 s −1 g −1 ). Mimani et al 46 synthesized CoFe 2 O 4 by a low-temperature decomposition approach and obtained a reaction rate constant of k s = 0.232 s −1 m −2 , while CoFe 2 O 4 materials synthesized by co-precipitation and sol–gel method led to significantly lower reaction rate constants of k m = 0.037 s −1 g −1 and k s = 0.04 s −1 m −2 , respectively.…”

“…The authors highlighted the importance of the electron exchange by redox couples and were not able to demonstrate any significant influence of Fe present in the spinel samples. Similarly, Onuchukwu and Zuru 45 prepared a Co x Fe 3− x O 4 spinel series by co-precipitation and investigated its catalytic activity in H 2 O 2 decomposition. They found Co 1.5 Fe 1.5 O 4 to be the best catalyst and explained this observation by the presence of each 0.5 mol Co 2+ and Co 3+ per formula unit in the octahedral voids of the spinel, enabling an optimal electron exchange between the redox couple within the octahedral sites.…”

“…They found Co 1.5 Fe 1.5 O 4 to be the best catalyst and explained this observation by the presence of each 0.5 mol Co 2+ and Co 3+ per formula unit in the octahedral voids of the spinel, enabling an optimal electron exchange between the redox couple within the octahedral sites. 45 However, H 2 O 2 decomposition was carried out in a highly alkaline environment. The present study identifies CoFe 2 O 4 to be the most active catalyst in acetonitrile, which does not contain the Co 2+ /Co 3+ redox couple at the octahedral sites.…”