The phase identity, composition were recorded by using a Rigaku D/Max 2200PC diffractometer with a graphite monochromator and Cu-K radiation (l 1/4 0.15418 nm). The structure, size, and shape of the products were characterized by a transmission electron
microscope (TEM, JEM100-CXII) with an accelerating voltage of 80 kV, a eld-emission scanning electron microscope (FE-SEM, Hitachi, S4800), and a high-resolution transmission electron microscope (HRTEM, JEM-2100) with an accelerating voltage of 200 kV.