Oriented Films of Metal-Organic Frameworks on Metal Hydroxides via Heteroepitaxial Growth

Framework compounds such as metal-organic frameworks (MOFs) are characterized by their micropores, which provide a large accessible surface for applications such as gas storage and catalysis. Additional functionalities for electronics, photonics, and magnetic applications can be attained by accommodating functional guests (molecules, ions, or nano-objects) into the pores. Device-scale MOF thin films with controlled crystallographic orientations must be achieved to enhance these sophisticated functionalities for practical applications. Recently, we reported the heteroepitaxial growth of MOFs via solution processing of precursor metal hydroxide-oriented films. The resultant MOF film exhibited crystallographic orientation along all three axes, which can be used as quasi-single crystals because the pores are aligned in specific directions at the macroscopic scale. The orientation primarily depends on the crystallographic plane of the seed metal hydroxide layer. In this article, recent advances in the fabrication and application of oriented MOF films are reviewed.