Abstract
Strain engineering enables the direct modification of atomic bonding and is currently an active area of research aimed at improving electrocatalytic activity. However, directly measuring the lattice strain of individual catalyst nanoparticles is challenging, especially at the scale of a single unit cell. Here, we quantitatively map the strain present in rhodium@platinum (core@shell) nanocube electrocatalysts using conventional aberration-corrected scanning transmission electron microscopy (STEM) and the recently developed technique of 4D-STEM nanobeam electron diffraction. We demonstrate that 4D-STEM combined with data preconditioning allows for quantitative lattice strain mapping with subpicometer precision and without the influence of scan distortions. When combined with multivariate curve resolution, 4D-STEM allows us to distinguish the nanocube core from the shell and to quantify the unit cell size as a function of distance from the core-shell interface. Our results demonstrate that 4D-STEM has significant precision and accuracy advantages in strain metrology of catalyst materials compared to aberration-corrected STEM imaging and is beneficial for extracting information about the evolution of strain in catalyst nanoparticles.
| Original language | English |
|---|---|
| Pages (from-to) | 5529-5541 |
| Number of pages | 13 |
| Journal | ACS Catalysis |
| Volume | 10 |
| Issue number | 10 |
| DOIs | |
| State | Published - May 15 2020 |
Funding
This research was supported by ORNL’s Laboratory Directed Research and Development (LDRD) Program, which is managed by UT-Battelle, LLC, for the U.S. Department of Energy (DOE) (D.M. and R.R.U.). J.T.L.G. and S.E.S. were supported by U.S. DOE BES Award DE-SC0018961. Electron microscopy was conducted as part of a user proposal at Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. D.M. and R.R.U. acknowledge the use of resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. DOE under Contract no. DE-AC05-00OR22725. We thank Michael Zachman and Jordan Hachtel for helpful discussions. D.M. thanks Andrew Lupini for help with setting up the nanodiffraction imaging on the NION microscopes.
| Funders | Funder number |
|---|---|
| CADES | |
| Data Environment for Science | |
| U.S. DOE BES | DE-SC0018961 |
| U.S. Department of Energy | |
| Office of Science | DE-AC05-00OR22725 |
| Laboratory Directed Research and Development |
Keywords
- 4D-STEM
- core@shell
- electrocatalysts
- electron microscopy
- nanocatalysts
- strain engineering