Synthesis of zeolitic imidazolate framework-8 using an electric field in a gelled medium

Abstract

Using the ion migration in various gel mediums governed by a direct electric field is a well-known technique, especially in analytical chemistry, to separate charged chemical species. This approach is also suitable for generating different-sized crystals and controlling the pattern formation in gels. Here we present a synthesis of zeolitic imidazolate framework-8 in an agarose gel driven by a direct electric field. We investigate the effect of an applied electric current on the macroscopic pattern formed in the gel, morphology, size, and dispersity of the ZIF-8 crystals. Upon increasing the electric current, the average size of the particles and dispersity of the samples decreased along the gel tube from the liquid–gel interface of the anodic side. This trend is opposite to the results obtained in synthesising particles utilizing only diffusion for mass transport. The electric field caused peak-doubling in the X-ray diffraction (XRD) pattern. To support the experimental observations, we developed a reaction–diffusion–migration model, which qualitatively describes the pattern formation observed in experiments.