Figure 1

TEM images of CoO samples S1 (a) and S2 (c). The insets in (a) and (c) display the log-normal size distribution of particles. High-resolution (HRTEM) images of S1 (b) and S2 (d) revealing the regular arrangement of lattice fringes. The corresponding fast Fourier transform (FFT) of images are displayed in the insets in (b) and (d) and show the spacing of 0.24 nm and 0.21 nm at [111] and [200] orientations of CoO phase, respectively