| AVS 65th International Symposium & Exhibition | |
| In-situ Microscopy, Spectroscopy, and Microfluidics Focus Topic | Monday Sessions |
| Session MM+AS+NS+PC-MoM |
| Session: | Mechanical, Electrical, Thermal and Optical Systems for In situ TEM (9:00-10:100 am)/Beam Induced Effects and Processing in Liquid/Gas Cells for TEM/SEM (10:40-11:40 am) |
| Presenter: | Raymond Unocic, Oak Ridge National Laboratory |
| Authors: | R.R. Unocic, Oak Ridge National Laboratory X. Sang, Oak Ridge National Laboratory A. Belianinov, Oak Ridge National Laboratory O.S. Ovchinnikova, Oak Ridge National Laboratory K. More, Oak Ridge National Laboratory S. Jesse, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
There are a wide range of solution-based strategies available for the size- and shape-controlled synthesis of functional nanomaterials for applications in catalysis, energy storage, biomedical, optical, and electronics. To elucidate growth mechanisms, in situ liquid scanning transmission electron microscopy (STEM) plays a role for directly imaging and quantifying growth dynamics of nanoparticles from liquid-phase precursors. In this work, we report several strategies for the active controlled synthesis of metallic and bimetallic nanoscale architectures using the concept of radiolytic synthesis. In one approach, we developed a direct-write, template-free method to fabricate self-supporting, hollow, metallic nanostructures, and we interpret the formation mechanisms based on direct observations of nucleation and growth. The electron beam used for imaging stimulates radiolysis, promoting the dissociation of water (H2O) molecules and the formation of complex radical species such as aqueous electrons (eaq-) and other reducing and oxidizing species. The highly reducing radiolytic species assist in the chemical reduction of metal ions from the precursor solution, resulting in the formation of a metallic nanocrystal seed, which then acts as a catalyst for H2 gas generation forming a metal encapsulated hollow nanobubble. In another approach, a custom-built electron beam nanopositioning and scan-generator system is used to precisely control the position and electron dose of the focused electron or ion beam to fabricate metallic and bimetallic nanostructured materials. These strategies enable fundamental electron beam interaction studies and open a new pathway for direct-write nanolithography from liquid-phase solutions.
This research was supported by the Center for Nanophase Materials Sciences, which is a United States Department of Energy Office of Science User Facility.