Controllable synthesis and photoelectric properties of interconnected and self-assembled nanocomposite of porous hollow Cu7S4/CuS and nitrogen-doped graphene oxide

In this work, the novel, interconnected and self-assembled nanocomposite of porous hollow Cu7S4/CuS and nitrogen-doped reduced graphene oxide (Cu7S4/CuS@nGO) has been designed and synthesized successfully via a simple solvothermal process. An efficiently synthetic approach to selectively manufacture different morphologies of Cu7S4/CuS has been investigated by only controlling the hydrothermal temperature. The images of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate the temperature-dependent evolution of structures and morphologies of the samples. Considering the efficient morphology of Cu7S4/CuS(synthesized at 210 °C) with the porous hollow spherical structure, we speculate it should have good photoelectric properties, such as wide UV–vis absorption spectra, and its performance should be enhanced with further treatment like being encapsulated with nitrogen-doped reduced graphene oxide. In order to investigate the photoelectric properties of the Cu7S4/CuS and Cu7S4/CuS@nGO nanocomposites, they have been used as the counter electrodes (CE) in the dye-sensitized solar cells (DSSC). It is demonstrated that the Cu7S4/CuS@nGO nanocomposite not only shows the best photoelectric performance, whose power conversion efficiency is 9.14% (much higher than those of the devices with Pt, Cu7S4/CuS and nGO as CEs), but possesses remarkable electrochemical stability as well.