Revisiting Water Oxidation Reaction with Micro Bubble Lithography (MBL) Printed ZIF-67 MOF Electrocatalysts

Microbubble-based micro-lithographic techniques have developed rapidly over the last ten years and are capable of reproducibly patterning a wide variety of soft materials and colloids, including polymers, metals, and proteins. Zeolitic imidazolate framework (ZIF) materials have attracted a great deal of research and application interest in the field of materials science because of their chemical and thermal stabilities. Furthermore, ZIF-67 has demonstrated significant potential for applications in gas adsorption, molecule separation, electrochemistry, and catalysis, which when converted into "lab-on-a-chip" platforms might produce remarkable and diverse application-oriented outcomes. This is due to their highly adjustable nanostructures. Using Co(OAc)₂.4H₂O and Co(NO₃)₂.6H₂O as the metal ion sources and 2-methylimidazole as the ligand, To design ZIF-67 (composed of Co²⁺ ions and imidazolate ligands) is attempted. Inspired by previous results, the Micro-Bubble Lithography (MBL) approach is used to successfully demonstrate an instantaneous in situ green synthesis and micro-patterning of ZIF-67 MOFs in this work. With reasonable stability and an over-potential of 440 mV, these micro-patterns are used as microelectrodes for the electrocatalytic oxygen evolution reaction (OER) in media having different pH.