Unveiling the Influence of Zeolite-Imidazole Framework Synthesis via the Precipitation Method on the Electrocatalytic Activity of Derived Carbon

Carbon materials derived from zeolite imidazole frameworks (ZIFs) hold significant promise as electrocatalysts for various electrochemical reactions, including the oxygen reduction reaction (ORR). However, rapid and large-scale production of ZIFs is crucial for obtaining electrocatalytically active carbon materials for widespread applications. Modifications of the solvent composition are necessary to enable the bulk synthesis of ZIFs; however, the impact of these changes on the electrochemical properties of the resulting electrocatalysts is often overlooked. This study investigated the influence of the different solvents used in the precipitation synthesis of bimetallic (Co and Zn) ZIFs on the electrocatalytic properties of the resulting carbon materials. Specifically, ZIFs were synthesized by using methanol, a water-triethylamine (TEA) mixture, and a water-dimethylformamide (DMF) mixture. The results indicate that ZIFs synthesized in a water-TEA mixture yield carbon materials (Co-TEA) with superior electrochemical performance, characterized by a higher density of active reaction sites and enhanced electrochemical performance and stability for the ORR, compared to those produced from methanol (Co-MOH) and water-DMF mixtures (Co-DMF). The study underscores the critical role of solvent choice in determining the morphology, porosity, and catalytic properties of ZIF-derived carbon. The surface-doped nitrogen content and balanced Co 3+ and Co 2+ ions in Co-TEA, along with the high density of mesopores, increased the reaction site density of Co-TEA compared with those of Co-MOH and Co-DMF. Notably, the electrochemical stability of Co-TEA surpasses those of Co-MOH, Co-DMF, and commercial Pt/C. Co-TEA exhibited a negative shift of only 17 mV in E 1/2 after 10,000 cycles between 0.6–1 V. These findings reveal that the electrochemical performance of the derived carbon is closely linked to the synthesis conditions, highlighting the potential of water-TEA-mediated ZIF synthesis as a promising strategy for developing nonprecious electrocatalysts for practical applications.