Direct Synthesis of Layered Intercalation Compounds and Single Layer Nanosheets and Their Applications

Layered materials have been extensively studied and have found a wide range of applications predominately in the form of intercalated layered hybrids, or as exfoliated single layer nanosheets. Previous investigations in layered materials mainly focused on the preparation of layered intercalation compounds and obtaining single layer nanosheets. The preparation of layered intercalation compounds and exfoliation to obtain single layer nanosheets typically consists of two steps, where a layered material is first synthesized and subsequently intercalated/exfoliated through different approaches. However, the two step process is time consuming and inefficient. Moreover, the desired intercalation and exfoliation may not proceed as planned. Thus, it is highly desirable to explore new methodologies for facile synthesis of layered intercalation compounds and single layer nanosheets. This dissertation reports a novel approach to directly synthesize layered intercalation compounds and single layer nanosheets via a one-step process. Two model layered compounds: α-zirconium phosphate (α-ZrP) with negative layer charge and layered double hydroxide (LDH) with positive layer charge were selected for the one-step direct synthesis of layered intercalation compounds and single layer nanosheets, respectively. The introduction of a layer growth coordinator and inhibitor was proposed to guide or inhibit the growth of layered materials in the third dimension for the formation of layered intercalation compounds and single layer nanosheets, respectively. Our results have proved that the proposed one-step direct synthesis process to obtain layered intercalation compounds and single layer nanosheets is feasible. Detailed reaction mechanisms and the factors that influence the direct synthesis of layered intercalation compounds and single layer nanosheets were studied in detail. Based on the aforementioned fundamental investigation, another strategy involving both a complexing agent and a layer growth coordinator was further designed to promote the growth of layered compounds in the Z direction to form hexagonal prisms. Applications of the α-ZrP based intercalation compounds and LDH single layer nanosheets prepared through the developed methods were also studied. The Biginelli reactions catalyzed by the heterogeneous α-ZrP/BMIMCl intercalation compound were explored where the yield was maintained at 93% even after 4 times of recycle. A dip coating method was adopted to align LDH single layer nanosheets on polymer film substrates to enhance their barrier properties, where both the oxygen and water vapor barrier properties were significantly improved.