HRTEM provided additional structural information concerning the in situ growth of the BiOCl nanoplates within the titania network. Panels a and b of Figure 5 reveal that the as-prepared nanocomposite is composed of well-distributed 2D BiOCl nanoplates well assembled into the porous TiO2 structure. A close-up image of a single BiOCl nanoplate reveals its high crystallinity (Figure 5c), and the same holds for the TiO2 network (Figure 5e). The selected area electron diffraction (SAED) pattern acquired from an individual BiOCl nanoplate (Figure 5d) shows a regular and clear square diffraction spot array with lattice spacings matching those of (113) and (012) planes, demonstrating the existence of the BiOCl tetragonal structure, which, in turn, is in agreement with the XRD results. The SAED pattern taken on the TiO2 regions (Figure 5f) shows diffused lattice fringes, with an interplanar distance of 0.34 nm corresponding to the (101) d spacing of anatase TiO2, confirming its nanocrystalline nature. Furthermore, it is clearly seen that the BiOCl has grown into close contact with the TiO2 matrix, providing a tightly packed heterojunction structure. The specific surface area of pure TiO2 (PT) is 161 m2 g−1 and decreases slightly to 117 m2 g−1 when BiOCl is stacked to the TiO2 network. This can be ascribed to the presence of the nonporous oxychloride chunks that partially shield the porosity of TiO2. Nevertheless, the BiOCl-PT nanocomposite has a surface area more than 2 times larger than that of the commercial titania termed Degussa P25 (56 m2 g−1 ).36 Such BiOCl-PT structure with a large surface area and threedimensional connected pore framework could play an important role in catalyst design because of their potential capacity to improve the molecular diffusion of reactants and products.