Sintering-resistant $Pt@CeO_2$ nanoparticles for a high-temperature oxidation catalyst

Abstract

The key factor that has limited the industrial utilization of the nano-sized metal catalysts is their poor thermal stability and the resulting performance degradation, while many industrial catalytic processes, such as automotive emission control, hydrocarbon reforming and electrocatalytic reactions, run at elevated temperatures (> $500 ^\circ C$). To avoid this problem, there have been many attempts to develop thermally stable metal catalysts but they still remain unsatisfactory. Here, we address this issue by designing a post encapsulated composite structure, in which individual Pt nanoparticles are surrounded by gas-permeable and catalytically active $CeO_2$ shells. Kinetically confined oxide precipitation method enabled to uniformly coat the Ce precursor layer onto the Pt cores with remarkably controlled shell thickness between 2.9 and 26.5 nm. The enhanced metal-support interactions significantly prevent the agglomeration of Pt cores, while leading to exceptionally high reactivity for methane combustion. For the particles with 13.8 nm thick shell, we observed $100 ^\circ C$ lower $T_{10}$ temperature and 8 times higher reaction rate, compared with a bare mixture of Pt and $CeO_2$ nanoparticles, maintaining complete methane oxidation more than 50 h at $700 ^\circ C$. The results provide improved guidelines toward the design of a sintering resistant, high performance catalyst for elevated temperature.