Effect of Jahn−Teller Distortion in La 0.5 Sr 0.5 MnO 3 Cubes and Nanoparticles on the Catalytic Oxidation of CO and CH 4

La 0.5 Sr 0.5 MnO 3 cube and nanoparticle catalysts were synthesized by the hydrothermal and coprecipitation method, respectively. The catalytic performances for CO and CH 4 oxidation were evaluated, and the effect of Jahn−Teller distortion on the catalytic performance was elucidated. La 0.5 Sr 0.5 MnO 3 nanoparticle catalyst showed a higher activity than the cube catalyst for CO oxidation at a lower temperature. While the catalytic activity of the cubes significantly increased at higher temperature, the complete conversion temperatures for CO were both the same at 210 °C. The trend for CH 4 oxidation activity was similar to the trend observed for CO oxidation activity. The catalytic mechanism of CO oxidation over La 0.5 Sr 0.5 MnO 3 cubes is proposed that the adsorbed CO was oxidized by the lattice oxygen. Then, the chemisorbed oxygen over La 0.5 Sr 0.5 MnO 3 cubes was transformed into the lattice oxygen by MnO 6 octahedra to reinforce the consumed lattice oxygen. The catalytic performances of La 0.5 Sr 0.5 MnO 3 cubes and nanoparticles were mainly predominated by Jahn−Teller distortion of the catalysts.