Improving the catalytic activity of CeO2/H2O2 system by sulfation pretreatment of CeO2

• Sulfated ceria shows enhanced activity in catalytic degradation of AO7 with H2O2.
• Sulfated ceria exhibits stronger surface acidity compared with bare CeO2.
• Sulfation of CeO2 activates the surface peroxide species for degradation of AO7.
• A mechanism for the catalytic activity improvement of sulfated ceria is proposed.

Organic pollutants can be effectively degraded by CeO2/H2O2 system, the catalytic activity of which is restricted by over-complexation of H2O2 with CeO2. In this study, nano ceria was pretreated simply in different ways. Degradation of AO7 was employed to evaluate the catalytic activity of the pretreated ceria samples in the presence of H2O2 in pre-adsorbed mode (AO7 pre-adsorbed on CeO2 before the addition of H2O2) and pre-mixed mode (CeO2 pre-mixed with H2O2 before the addition of AO7). Two sulfated ceria samples (H2SO4–CeO2 and Na2SO4–CeO2) exhibit enhanced catalytic performance in both modes compared with un-pretreated bare CeO2. XRD, BET, FTIR and potentiometric titration methods were used to characterize the pretreated ceria samples. The sulfated samples display stronger surface acidity due to the sulfate ions anchored on their surface. Raman and XPS measurements were carried out to analyze the samples after reacting with H2O2. A mechanism to explain the improved catalytic activity of sulfated CeO2 is proposed that the active surface peroxide species (Ce(III)O2H−), which are excessive due to the over-complexation of H2O2 with surface Ce3+ sites, can be decomposed into high-active hydroxyl radicals under surface acidic environment.

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