Fig. 2. (a) TEM images of Co-CoPBA; (b) high-resolution images; (c) electron diffraction images; (d) TEM images of WO₃; (e) high-resolution images; (f) electron diffraction images; (g) TEM images of WO₃@Co-CoPBA-500 °C; (h) high-resolution images; (i) electron diffraction pattern.