Abstract
Zeolites are aluminosilicate materials that contain regular three-dimensional arrays of molecular-scale pores, and they can act as hosts for catalytically active metal clusters1. The catalytic properties of such zeolites depend on the sizes and shapes of the clusters, and also on the location of the clusters within the pores. Transmission electron microscopy has been used to image single atoms and nanoclusters on surfaces2, but the damage caused by the electron beam has made it difficult to image zeolites3,4. Here, we show that aberration-corrected scanning transmission electron microscopy can be used to determine the locations of individual metal atoms and nanoclusters within the pores of a zeolite. We imaged the active sites of iridium catalysts anchored in dealuminated HY zeolite crystals, determined their locations and approximate distance from the crystal surface, and deduced a possible cluster formation mechanism.
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Acknowledgements
This work was supported by the National Science Foundation (NSF) and ExxonMobil (V.O., by NSF Grant Opportunities for Academic Liaison with Industry, grant no. CTS-0500511) and by the Department of Energy (DOE) (A.U., grant no. DE-FG02-04ER15600). The STEM images were acquired at Oak Ridge National Laboratory's Shared Research Equipment User Facility, supported by the Division of Scientific User Facilities, Basic Energy Sciences, DOE.
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V.O. performed the experiments, analysed the data and wrote the paper. A.U. carried out synthesis of the catalyst samples. V.O., A.U., B.C.G. and N.D.B. conceived and designed the experiments. All authors discussed the results and commented on the manuscript.
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Ortalan, V., Uzun, A., Gates, B. et al. Direct imaging of single metal atoms and clusters in the pores of dealuminated HY zeolite. Nature Nanotech 5, 506–510 (2010). https://doi.org/10.1038/nnano.2010.92
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DOI: https://doi.org/10.1038/nnano.2010.92
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