A General Synthesis of Nanostructured Conductive MOFs from Insulating MOF Precursors for Supercapacitors and Chemiresistive Sensors

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) are emerging as unique layer-stacked crystalline coordination polymers that simultaneously possess porous and conductive properties. However, the controlled synthesis of hierarchically nanostructured 2D c-MOFs with high crystallinity and customized morphologies is essential for energy and electronic devices, which remains a great challenge. Herein, we present a template strategy to synthesize 12 different 2D c-MOFs with controlled morphologies and dimensions via insulating MOFs-to-c-MOFs transformations. The resultant hierarchically nanostructured 2D c-MOFs feature intrinsic electrical conductivity (up to 102 S cm-1) and higher surface areas (up to ~62 times) than the reported bulk-type 2D c-MOFs, which are beneficial for improved access to active sites and enhanced mass transport. As proof-of-concept applications, the resultant hollow Cu-BHT nanocube-based supercapacitor exhibits over 2.3-fold improvement in specific capacity (364.5 F g-1) in organic electrolyte than the bulk-type Cu-BHT (161.9 F g-1), surpassing the reported MOF-based electrodes (up to 202 F g-1). In addition, the Cu-HHB nanoflower-based chemiresistive gas sensor displays over 2.5-fold enhancement in response intensity toward H2S compared to bulk-type Cu-HHB, boasting the fastest response speed and one of the lowest limits of detection ever reported for H2S sensors at room temperature.