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Homogeneous catalysts are advantageous in selective catalysis due to the well-defined active site at the molecular level. The poor recyclability, bimolecular aggregation, and undesired poison resistance of homogeneous catalysts hinder further industrial application despite the controlled reaction pathway due to the homogeneous environment. On the other hand, heterogeneous catalysts are preferred in industry due to their high recyclability and high activity. Yet, poor selectivity due to undefined active sites is a drawback. The construction of a host-guest system where a molecular level catalyst is incorporated into the Metal-Organic Framework (MOF) provides a promising solution to bridge those two fields. This composite maintains the advantages of homogeneous and heterogeneous catalysts and overcomes the disadvantages. However, finding an incorporation method that is versatile with minimum synthetic modification of the host and guest remains one of the challenges. In the first part of this dissertation, a new concept called “aperture-opening encapsulation’’ is introduced for incorporating large and diverse guest molecules into MOFs without changing the identity of either the guest or MOF. The approach capitalizes on the existence of linker exchange reactions, which, as our kinetic studies show, proceed via competition between associative and dissociative exchange mechanisms. The second part describes how this method is applied to incorporate a molecular catalyst into the cavity of UiO-66 for the hydrogenation of carbon dioxide to formate, which is a useful application for energy related industry. The developed hybrid composite showed the ability to be recycled, showed no evidence of bimolecular catalyst decomposition, and was less prone to catalyst poisoning. These results demonstrate for the first time how the aperture-opening process resulting from linker dissociation in MOFs can be utilized as a strategy to synthesize host-guest materials useful for chemical catalysis. After the establishment of the hybrid catalyst, the last part of the dissertation describes our efforts into the investigation of mass transport in catalysis. The understanding of the interaction between the host-guest is beneficial for the development of biological analogs in the future.

Polymer solar cells (PSCs), a member of organic solar cell family, have attracted increasing research interest. PSCs possess significant advantages over their inorganic solar cell counter parts: mechanical flexibility, light weight, low expense, and the potential to achieve roll-to-roll large-scale production. Tandem solar cells, in which two solar cells are linked to take more use of the solar energy, were fabricated with each solution processed layer using Bulk Heterojunction (BHJ) materials comprising semiconducting polymers and fullerene derivatives. For years, tremendous efforts have been put in seeking for an efficient intermediate layer to successfully connect two sub-cells together in the tandem structure. Even though many kinds of intermediate layers such as ZnO/MoO3 etc. have been explored, most of them suffer from the low conductivity or complicated manipulation disadvantages. Barium oxide (BaO) is both high conductive and wide bandgap n-type semiconductor. We successfully fabricated the polymer tandem solar cell using all thermal vacuum deposition fashion with BaO/Ag/MoO3 as an intermediate layer. VOC of the tandem structure is the sum of the component cells demonstrating our proposed intermediated layer can efficiently connect sub-cells with no potential/energy loss.