Governing the Porosity and Morphology of Zeolitic Imidazolate Framework-Derived Functional Carbons toward Improved Adsorption of Cationic Dyes

Abstract

Nitrogen-rich porous carbons prepared from zeolitic imidazolate frameworks (ZIFs) offer a promising platform for the effective confinement of small guest molecules. However, a key challenge within the domain of liquid-phase adsorption lies in the prevailing microporosity of ZIF-derived carbons, which impedes the diffusion of larger molecules and hinders the adsorption efficiency. In order to maximize carbon availability, methods for reshaping the particle morphology and generating mesoporosity are being dynamically developed. Herein, we present a strategy that addresses the limitations of conventional carbons from ZIF-8 and endeavors to increase the adsorption capacities toward organic pollutants via the generation of a dual-pore system along with the obtaining of diverse particle morphologies. We envisioned developing two strategies to synthesize unique ZIF precursors. The first method focused on ZIF-8 preparation from zinc oxides in the form of nanoparticles or flowers. In the second approach, a ZIF-8 crystalline phase was transformed into a pseudopolymorphic phase (ZIF-CO 3 -1) with a two-dimensional structure. The present study unveils the unexplored application of ZIF-CO 3 -1 in preparing functional porous carbons. Owing to the architecture of the ZnO@ZIF-8 and ZIF-CO 3 -1 precursors, their high-temperature carbonization generated carbons with hierarchical porosity (micro/mesopores). Compared to the microporous carbons, the adsorbents exhibited superior performance toward removing Auramine-O and Brilliant Green dyes, with sorption capacities of 257−544 and 247−395 mg/g, respectively. Their efficiency is attributed to elevated textural parameters, rich surface chemistry, and particle morphology, which improved pore accessibility.