widely used in photodegradation of organic contaminants and photocatalytic evolution of O2.22−24 However, due to the rapid recombination of photogenerated electrons and holes, it has been found that the photocatalytic activity of BiVO4 is usually not satisfactory in practical applications.25 As one solution to this problem, combining two or more semiconductors with appropriate band alignment can considerably improve electron−hole pair separation and interfacial charge transfer efficiency, leading to effective promotion of photocatalytic activity.26,27 BiVO4/Cu2O and BiVO4/CeO2 nanocomposites are some representative examples reported to exhibit much enhanced photocatalytic activity.28,29 In this study, we demonstrate a facile and novel method for controlled fabrication of mesoporous BiVO4/Ag/AgCl ternary heterostructured microspheres (HSMSs) via a solid-phase dualion-exchange strategy together with subsequent visible-light induced reduction by using uniform BiOCl microspheres as the starting material. The synthesis strategy is schematically illustrated in Figure 1. As the precursor in this synthesis, uniform flower-like BiOCl microspheres, assembled from nanoflakes, are obtained via a simple solvothermal method. At stage I, NaVO3 and AgNO3 are first introduced into the BiOCl microspheres at room temperature through a facile impregnation method, which provides homogeneous distribution of the reagents at the nanoscale.30 The solid-state dual-ionexchange reactions take place during the 2-h annealing process at 400 °C, through which BiOCl microspheres are fully converted into mesoporous BiVO4/AgCl binary HSMSs. The involved chemical reactions for the preparation of BiVO4/AgCl HSMSs can be described as follows: