## 3 Results and Discussion
**Figure 4.** Energy dispersive spectroscopy (EDS) spectrum recorded with a 35 nm electron probe from the \"cauliflower-like\" ZnO microparticle (marked by the circle on the inset image) showing characteristic peaks of the elements Zn and O. The Cu peak is from the specimen grid. In a previous study conducted by our research group, spherical porous ZnO microparticles (Figure 6B) were prepared by a similar procedure to that described above for the formation of \"Cauliflower-like\" ZnO microparticles (Figure 6C), substituting the ZnCl\({}_{2}\) precursor by zinc acetate [16]. In order to understand the formation mechanisms of each of the two different shapes of ZnO microparticles, we examined the Zn distribution within the PDVB template microspheres for both Zn precursors: ZnCl\({}_{2}\) and zinc acetate. In the first case, the added ZnCl\({}_{2}\) significantly decreased the surface area of the porous PDVB template microspheres, as calculated by the Brunauer-Emmett-Teller method, from 626 m\({}^{2}\)/g to 245 m\({}^{2}\)/g (Figure 7A). The pore volume, estimated from the desorbed amount of N\({}_{2}\), was decreased from 1.52 cm\({}^{3}\)/g for the PDVB microspheres to 0.48 cm\({}^{3}\)/g to the ZnCl\({}_{2}\)-PDVB microspheres. In addition, the BJH pore-size distribution curves (Figure 7B) demonstrate that both intra-particle micropores and mesopores volume were decreased by the addition of ZnCl\({}_{2}\), although the decrease of the mesopores volume is more significant. This suggested that the ZnCl\({}_{2}\) was penetrated mostly to the inter-particles mesopores, and indeed, SEM images of the ZnCl\({}_{2}\)-PDVB composite microspheres demonstrate clearly that the ZnCl\({}_{2}\) adsorbed on the PDVB particles' outer surface (Figure 8). Figure 5: “Cauliflower-like” ZnO microparticles: (**A**) Light and fluorescent; (**B**) microscope images. (Original magnification: \(\times\)400). Figure 6: SEM images of (**A**) polydivinyl benzene (PDVB) template microspheres; and (**B**) ZnO microparticles prepared using the zinc acetate precursor; or (**C**) the ZnCl\({}_{2}\). Elemental line scan and point EDS techniques were used for elemental analysis of the ZnCl\({}_{2}\) composite microspheres (Figure 9). Elemental analysis was performed in EDS mode and the spectrum (inset B) taken from ~35 nm area of a microsphere shows that the elements Zn, Cl, C, O and Cu (from the specimen grid) are all present in the sample. Analysis of the distribution of ZnCl\({}_{2}\) in the ZnCl\({}_{2}\)-PDVB microspheres was conducted in the STEM mode. Figure 9A displays the line scan profile for Zn (yellow) performed on ZnCl\({}_{2}\)-PDVB microspheres. Figure 9: Bright field scanning transmission electron mode (STEM) image of ZnCl\({}_{2}\)-PDVB microspheres. Elemental line scan is shown for Zn (inset **A**). The red arrow marks a line on the surface of the microspheres where the line scan was performed. The figure shows the EDS spectrum recorded from a 35 nm area of a microsphere showing characteristic peaks of the elements C, O, Cl and Zn in the analyzed area. The Cu peak is from the specimen grid. The line scan performed demonstrates that the ZnCl\({}_{2}\) nanoparticles are partially embedded in the carbon matrix but are mostly distributed on the surface of the PDVB microspheres. We suggest that the ZnCl\({}_{2}\), which was concentrated mostly on the PDVB microspheres surface, was crystallized as ZnO in a typical hexagonal rods structure [19] around the PDVB microspheres. The PDVB organic microspheres were totally combusted during the calcination, leaving porous spherical patterns of \(\sim\)1-2 \(\upmu\)m embossed in the ZnO hexagonal rods and thus providing it \"cauliflower-like\" appearance. The portion of ZnCl\({}_{2}\) which was penetrated into the PDVB microspheres, created small round nanoparticles (\(\sim\)10 nm) observed within the spherical deficiencies formed by the PDVB template particles (Figure 6C). ZnCl\({}_{2}\) is a polar inorganic salt, with low solubility in organic solvents.