The perovskite crystal structure has a remarkable tolerance for vacancies and elemental substitutions, making a great breadth of chemical and physical properties accessible. It also offers a unique route to generate sinter-resistant nanoparticles when reduced at elevated temperatures. Copper is well known for oxidation reactions; however, its catalytic activity can be limited by regeneration of its oxidation state. Manganese can not only assist in regenerating the oxidation state, but can activate oxygen molecules, improving the activity of copper. Catalyst synthesis with perovskites and copper-manganese synergy then is a promising route to rationally design an oxidation catalyst with sinter-resistance. However, we found that lanthanum manganese perovskite oxide is resistant to generating copper nanoparticles, even at reduction temperatures up to 550 C. Therefore, we investigate this resistance with two goals in mind. First, we investigate techniques such as lanthanum vacancies and elemental substitutions to make copper more susceptible to surface nanoparticle formation. Second, we determine parameters that affects the resulting copper nanoparticle morphology and catalytic activity. With this investigation, we report on our ability to control the synthesis of copper nanoparticles on a lanthanum manganese perovskite oxide, suggest why this perovskite is resistant to copper nanoparticle formation, and propose optimizations for our probe reaction, CO oxidation.

Utilizing lanthanum perovskite oxides to create a better copper-manganese oxidation catalyst

ACS Spring Meeting 2021

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