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Research Highlight

Measuring and Directing Charge Transfer in Heterogenous Catalysts

Measuring and directing charge transfer in heterogenous catalysts
Annular dark field STEM images (A,C left) and corresponding charge density maps (B,C right) of Au/STO (top row) and oxygen treated Au/STO (bottom row).

Scientific Achievement

We demonstrate a robust scanning transmission electron microscopy (STEM) method that simultaneously visualizes the atomic-scale structure and sub-nanometer-scale charge distribution in heterogeneous catalysts.

Significance and Impact

Strong metal support interactions (SMSI) have perplexed and intrigued researcher in catalysis for a century and are critical to understanding how reducible oxide supports enhance catalysis. Our work provides an effective method to elucidate the nature of electronic interactions associated with SMSI that have previously been inaccessible to conventional microscopy and opens opportunities to understand SMSI and impacts on catalytic mechanisms.

Research Details

  • Charge redistribution and atomic-scale structure and chemistry in a heterogeneous catalyst – Au nanoparticles supported on SrTiO3 (Au/STO) - were probed simultaneously for the first time by advanced 4D-STEM.  
  • Combining 4D-STEM, DFT, and catalytic activity measurements provides direct evidence of the perimeter region serving as the predominant active site in heterogeneous catalysis, information previously inferred via theoretical calculations or indirect experimental methods.  
  • The direction of charge transfer can be reversed using post-synthesis treatments that results in different catalytic activities in CO oxidation.

M.J. Zachman, V. Fung. F. Polo-Garzon, S. Cao, J. Moon, Z. Huang, D. Jiang, Z. Wu, and M. Chi, Nature Communications 13 3253 (2022)