Solvent‐Induced Cadmium(II) Metal‐Organic Frameworks with Adjustable Guest‐Evacuated Porosity: Application in the Controllable Assembly of MOF‐Derived Porous Carbon Materials for Supercapacitors

In this work, five new cadmium metal‐organic frameworks (Cd‐MOFs 1 – 5 ) have been synthesized from solvothermal reactions of Cd(NO 3 ) 2 ⋅ 4 H 2 O with isophthalic acid and 1,4‐bis(imidazol‐1‐yl)‐benzene under different solvent systems of CH 3 OH, C 2 H 5 OH, (CH 3 ) 2 CHOH, DMF, and N‐methyl‐2‐pyrrolidone (NMP), respectively. Cd‐MOF 1 shows a 3D diamondoid framework with 1D rhombic and hexagonal channels, and the porosity is 12.9 %. Cd‐MOF 2 exhibits a 2D (4,4) layer with a 1D parallelogram channel and porosity of 23.6 %. Cd‐MOF 3 has an 8‐connected dense network with the Schäfli symbol of [4 24 ⋅6 4 ] based on the Cd 6 cluster. Cd‐MOFs 4 – 5 are isomorphous, and display an absolutely double‐bridging 2D (4,4) layer with 1D tetragonal channels and porosities of 29.2 and 28.2 %, which are occupied by DMF and NMP molecules, respectively. Followed by the calcination‐thermolysis procedure, Cd‐MOFs 1 – 5 are employed as precursors to prepare MOF‐derived porous carbon materials (labeled as PC ‐ me , PC ‐ eth , PC ‐ ipr , PC ‐ dmf and PC ‐ nmp ), which have the BET specific surface area of 23, 51, 10, 122, and 96 m 2  g −1 , respectively. The results demonstrate that the specific surface area of PC s is tuned by the porosity of Cd‐MOFs, where the later is highly dependent on the solvent. Thereby, the specific surface area of PC s could be adjusted by the solvent used in the synthese of MOF precusors. Significantly, PC s have been further activated by KOH to obtain activated carbon materials ( APC s), which possess even higher specific surface area and larger porosity. After a series of characterization and electrochemical investigations, the APC ‐ dmf electrode exhibits the best porous properties and largest specific capacitances (153 F g −1 at 5 mV s −1 and 156 F g −1 at 0.5 Ag −1 ). Meanwhile, the APC ‐ dmf electrode shows excellent cycling stability (ca. 84.2 % after 5000 cycles at 1 Ag −1 ), which can be applied as a suitable electrode material for supercapacitors.