Direct identification of the charge state in a single platinum nanoparticle on titanium oxide

A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs. The analysis revealed the number (only one to six electrons) and sense (positive or negative) of the charge per platinum NP. The underlying mechanism of platinum charging is explained by the work function differences between platinum and titanium dioxide (depending on the orientation relationship and lattice distortion) and by first-principles calculations in terms of the charge transfer processes.

Automated summary

In this study, we directly identified the charge state of individual platinum nanoparticles supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. The analysis revealed the number and sense of the charge per platinum NP, and the underlying mechanism of platinum charging was explained by work function differences between platinum and titanium dioxide and first-principles calculations.