Fe–O terminated LaFeO3 perovskite oxide surface for low temperature toluene oxidation

Abstract

The surface termination of catalyst is vital to heterogeneous catalytic reaction process. Inactive A-site cations exposed over the perovskite oxide materials would limit the surface activity of studied samples. In this work, the surface composed of more Fe–O termination was synthesized over the LaFeO3 perovskite oxide and it shows performance superiority than more La–O exposed samples. Combined with the characterization results, exposure of more Fe–O termination would help boost the oxygen mobility and enhance the reducibility of LaFeO3 perovskite with higher hydrogen consumption (0.088 mmol/g) than that of untreated LaFeO3 sample (0.033 mmol/g). Based on the DFT calculation and XPS analyzation, exposure of the Fe–O termination surface would decrease the formation energy of oxygen vacancy and hence boost the oxygen cycle process, which would accelerate the redox process in return. Furthermore, more Fe–O exposed surfaces would cause the effective performance enhancement for the catalytic oxidation of toluene. After 5 h surface treatment, T50 and T90 of LFO-5 are 255.9 °C and 277.3 °C, much lower than that of untreated sample, which are 309.7 °C and 332.8 °C, correspondingly. In the meantime, the surface treated sample possess relative good stability under 20 h test. This work would benefit for the practical application and provide a better understanding to the potential of perovskite oxides.