Improved activity and significant O2 resistance of Cs doped Co3O4 catalyst for N2O decomposition

Abstract

Csx-Co3O4 catalysts with excellent low temperature activity and oxygen resistance for N2O decomposition were prepared using a citric acid complexation method. The mechanism of Cs doping on Co3O4 was systematically investigated by characterization techniques such as XRD, Raman, N2 adsorption, HR-TEM, XPS, H2-TPR, O2-TPD, and combined with DFT calculation methods. The results indicated that the presence of Cs inhibited the growth of Co3O4 grains and increased the specific surface area. Cs doping significantly increased the number of exposed oxygen vacancies, which tended to form around CoO4 (Co2+) tetrahedral sites replaced by Cs, following the trend Evac(1 1 1) <Evac(1 1 0) <Evac(1 0 0). Furthermore, the interaction between Cs and Co enhanced the electron donating ability of Co, promoted the reduction of Co3+ to Co2+ and weakened the Co-O bond. Among all the samples, the one with a Cs/Co molar ratio of 0.1 exhibited the highest activity. At 275 °C, the Rs of Cs0.1-Co3O4 was 39.5 times that of pure Co3O4. More importantly, Cs0.1-Co3O4 exhibited excellent oxygen resistance, achieving a high N2O conversion rate of 94 % under conditions of 300 °C and 20 % O2.