Atomic and nanoscale imaging of a cellulose nanofiber and Pd nanoparticles composite using lower-voltage high-resolution TEM

We have examined the advanced application of transmission electron microscopy (TEM) for the structural characterization of a composite of cellulose nanofiber (CNF) and palladium (Pd) nanoparticles. In the present study, we focused on electron-irradiation damage and optimization of high-resolution TEM imaging of the composite. The investigation indicates that the CNF breaks even under low-electron-dose conditions at an acceleration voltage of 200 kV. We then applied lower-voltage TEM at 60 kV using a spherical aberration corrector and a monochromator, in order to reduce electron-irradiation damage and improve the spatial resolution. The TEM observation achieved high-resolution imaging and revealed the existence of small Pd nanoparticles, around 2 nm in diameter, supported on the CNF. It is considered that the use of a monochromator in combination with spherical aberration correction contributed to the atomic and nanoscale imaging of the composite, owing to the improvement of the information limit under a lower-acceleration voltage.