Self-Assembly and Oriented Growth of Conductive Ni-CAT-1 Metal-Organic Framework at Solid-Liquid Interfaces

Two-dimensional (2D) conductive metal-organic frameworks (MOF) represent a unique class of electrode materials with high capacity and power density. Understanding molecular mechanisms and pathways for heterogeneous nucleation of 2D pi-conjugated MOFs is highly desirable for controlling the structure and properties of conductive MOFs on solid substrates. Herein, a systematic study of nucleation and growth of 2D pi-conjugated Ni-catecholate (Ni-CAT-1) MOFs on highly oriented pyrolytic graphite (HOPG) and copper substrates is reported. It is discovered that the nucleation density and growth kinetics of the MOF film can be controlled by varying substrate interactions with the organic linker. Specifically, pi-pi interactions between the linker and the HOPG dictate lower nucleation density, whereas pi-metal interactions between the linker and the copper substrate dictate faster nucleation and higher nucleation densities. These studies reveal the key mechanism for Ni-CAT-1 nucleation on different surfaces and provide insights into interfacial control over the growth of other 2D pi-conjugated MOF films on solid substrates to inform synthesis of functional materials.