Direct Electrochemical Synthesis of Metal-Organic Frameworks: Cu3 (BTC)2 and Cu(TCPP) on Copper Thin films and Copper-Based Microstructures

Abstract

Cu thin films and Cu₂ O microstructures were partially converted to the Metal-Organic Frameworks (MOFs) Cu₃ (BTC)₂ or Cu(TCPP) using an electrochemical process with a higher control and at milder conditions compared to the traditional solvothermal MOF synthesis. Initially, either a Cu thin film was sputtered, or different kinds of Cu or Cu₂ O microstructures were electrochemically deposited onto a conductive ITO glass substrate. Then, these Cu thin films or Cu-based microstructures were subsequently coated with a thin layer of either Cu₃ (BTC)₂ or Cu(TCPP) by controlled anodic dissolution of the Cu-based substrate at room temperature and in the presence of the desired organic linker molecules: 1,3,5-benzenetricarboxylic acid (BTC) or photoactive 4,4',4'',4'''-(Porphine-5,10,15,20-tetrayl) tetrakis(benzoic acid) (TCPP) in the electrolyte. An increase in size of the Cu micro cubes with exposed planes [100] of 38,7 % for the Cu₂ O@Cu₃ (BTC)₂ and a 68,9 % increase for the Cu₂ O@Cu(TCPP) was roughly estimated. Finally, XRD, Raman spectroscopy and UV-vis absorption spectroscopy were used to characterize the initial Cu films or Cu-based microstructures, and the obtained core-shell Cu₂ O@Cu(BTC) and Cu₂ O@Cu(TCPP) microstructures.

Keywords: Copper; electrochemical synthesis; metal-organic frameworks; microstructures; surfaces.