Fig. 1

Synthesis and characterization of the ZnO-Cu2O hybrid nanoparticles. a Synthesis of ZnO-Cu2O hybrid nanoparticles via a two-step in situ process. b TEM image of ZnO-Cu2O nanoparticles. c HRTEM and d STEM images, and e elemental mapping of an individual ZnO-Cu2O nanoparticle. The bars represent b 50, c 5, and d, e 20 nm. f XRD and g UV–Vis spectra of ZnO-Cu2O hybrid nanoparticles. XPS spectra of ZnO-Cu2O hybrid nanoparticles in the regions of h Zn 2p3/2 and i Cu 2p3/2