In our previous work, plate-stratiform nanostructured Bi12O17Cl2 with visible-light-response was prepared and characterized. The plate-stratiform Bi12O17Cl2 is stacked by a parallel array of ultrathin nanosheets, which parallelly aligned and closely superimposed. Since the exfoliation of graphene and C3N4 nanosheets from their bulk counterparts can bring unfolding exceptional properties, a facile and reliable method for high-yield production of Bi12O17Cl2 ultrathin nanosheets to make full exploration of Bi12O17Cl2 photocatalytic potentials is urgently needed. Besides chemical exfoliation and thermal decomposition, mechanical exfoliation using high-energy ball milling has been accepted as a simple and efficient way to produce large quantities of two dimensional nanomaterials.
In this study, a simple one-step high-energy ball milling method is firstly presented for mechanical exfoliation of plate-stratiform structured Bi12O17Cl2 into nanosheets with thickness only in several nanometers. The produced nanosheets in desired nanometer scale possess much larger surface area and shorter transferring distance, which benefit photocatalytic activity. TEM observation proves gradual size reduction of nanosheet thickness with increasing grinding time of Bi12O17Cl2 plate-stratiform nanomaterials. Photoluminescence spectra prove that Bi12O17Cl2 untrathin nanosheet has higher emission intensity than original plate-stratiform Bi12O17Cl2, representing improved separation efficiency of photogenerated carriers. Adsorption ability and photocatalytic efficiency of Bi12O17Cl2 untrathin nanosheet were greatly enhanced after exfoliation. The crucial role of its exfoliation refinement on enhanced photocatalytic performance under visible light is discussed. This mechanical exfoliation method is not only easy, low cost and high-yielding, but also provides a more “clean” way for layer-structured bismuth-based materials into two-dimensional nanosheets with broad spectrum of properties.