Fig. 1: Schematic illustration of Mn, C-ZnO CTHSs formation process.

a Preparation of Mn, Zn-CPSs from solvothermal treatment of zinc acetate and manganese acetate with salicylic acid in the presence of PVP. b Step-by-step conversion of Mn, Zn-CPSs into Mn, C-codoped ZnO CTSHSs upon calcination at 550 °C for 3 h. c The underlying driving force for such hollow structure formation.