Synthesis of hierarchical ZnO/C hollow spheres constructed by octahedron for water treatment

Hierarchical hollow structures show particular properties and promising applications, and therefore have been attracting attention. To the best of our knowledge, ZnO/C hollow sphere constructed by octahedron has not been reported so far. In this paper, a solvothermal process has been developed to prepare precursor hollow spheres constructed by octahedron. The precursor can be converted to hollow ZnO/C spheres with well-preserved morphology via thermal decomposing. In order to research the formation mechanism, intermediate precursors were acquired at different reaction times, and a possible growth mechanism was also proposed. When the hierarchical ZnO/C hollow spheres constructed by octahedron were used as the adsorbents, the Langmuir model can well describe the adsorption isotherms. For Congo red and Pb(II), the maximum adsorption capacities are up to 392 and 314 mg g−1, respectively. Furthermore, the as-prepared ZnO/C displays good recyclability in the removal of Congo red. Our results provide new strategy for the synthesis of novel ZnO/C hollow sphere, which has promising adsorption ability for water treatment.