Fig. 1. (Colour online) Schematic of the synthesis process.

Fig. 2. (Colour online) Mesocrystal ZnO nanorods. (a) Schematic diagram of classical and non-classical crystallization. (b) SEM image of mesocrystal ZnONRs at a scale of 10 µm. (c) SEM image of mesocrystal ZnONRs at a scale of 5 µm. (d) Enlarged SEM image of mesocrystal ZnONRs at a scale of 500 nm containing small ZnONPs. (e) XRF scan of mesocrystal ZnONRs. (f) XRD pattern of mesocrystal ZnONRs.

Fig. 3. (Colour online) Structural properties of ZnONRs/rGO nanocomposite superstructure. (a) XRD patterns of ZnONRs, rGO, and ZnONRs/rGO nanocomposite superstructure in the diffraction angle range of 5°−60°. (b) FTIR spectra of ZnONRs, rGO, and ZnONRs/rGO nanocomposite superstructure in the 400−4000 cm⁻¹ wavenumber range. SEM images of rGO at a scale of (c) 1 µm and (d) 500 nm. SEM images of ZnONRs/rGO nanocomposite superstructure at a scale of (e) 30 µm and (f) 500 nm.

Fig. 4. (Colour online) Optical and electrical properties of mesocrystal ZnONRs and ZnONRs/rGO nanocomposite superstructure. (a) Optical transmittance spectra of mesocrystal ZnONRs and ZnONRs/rGO nanocomposite superstructure. (b) Absorption coefficient of mesocrystal ZnONRs and ZnONRs/rGO nanocomposite superstructure. (c) Band structure of mesocrystal ZnONRs and ZnONRs/rGO nanocomposite superstructure. (d) Schematic diagram of transitions in ZnONRs/rGO nanocomposite superstructure. The electrical conductivity maps of (e) mesocrystal ZnONRs and (f) ZnONRs/rGO nanocomposite superstructure.

Fig. 5. (Colour online) Photoconductivity of mesocrystal ZnONRs and ZnONRs/rGO nanocomposite superstructure. (a) Schematic representation of the photoconductivity measurement. The photoconductivity response of (b) mesocrystal ZnONRs and (c) ZnONRs/rGO nanocomposite superstructure by turning on/off the UV light.