ZnO and carbon nanocomposites for enhanced photoelectrochemical sensing activity: influence of the carbon content

In this work, carbon and zinc oxide (ZnO:C) nanocomposites were obtained by a hydrothermal reaction process. ZnO nanoparticles were first prepared by a homogeneous coprecipitation method. Nanocomposites with atomic concentrations of carbon ranging from 39.4 to 69.7 wt.% were then attained. The microstructure and morphology of each prepared nanocomposite was investigated by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The ZnO:C nanocomposites were found to present a wurtzite-type hexagonal crystalline structure that shifted towards an amorphous state with increasing C content. Results showed that incorporating the covalent carbon at O sites in the ZnO lattice causes lattice compression. Due to their low band-gap energies, the photoresponses of the ZnO:C nanocomposites extended into the visible region. The sensing characteristics of ZnO:C nanocomposite films were also investigated, and a major improvement in the photoelectrochemical (PEC) efficiency was obtained when the C content was 39 wt.%.