Efficient construction of low shrinkage xerogels via coordination-catalyzed in-situ polymerization for activated carbon xerogels with multi-dyes adsorption

Abstract

Obtaining large specific surface areas (SSA) for carbon xerogels poses a significant challenge due to the inevitable volume shrinkage of xerogel. Here, the Zn²⁺ coordination-catalyzed in-situ polymerization approach was proposed to fabricate xerogels with a low shrinkage of 13.03 % and a short preparation period of 24 ​h. In resorcinol-formaldehyde (RF) polymerization, ZnCl₂ could accelerate the reaction kinetics through the coordination of the Zn²⁺ and hydroxyl groups. The gel network with adjustable RF particles (46.5 nm-1.89 ​μm) and narrow neck structures was constructed by changing ZnCl₂ and ethanol contents, which could resist volume shrinkage during atmospheric drying without solvent exchange. The activated carbon xerogels (ACXs) with hierarchical structure were designed by one-step carbonization/activation due to the pore-forming of ZnCl₂. The obtained ACXs showed a large SSA of 1689 ​m²/g, multi-dyes adsorption capacity (methylene blue, Congo red, methyl orange, and Sudan III were 625.90, 359.46, 320.69, and 453.92 ​mg/g, respectively), and reusability of 100 %. The maximum monolayer MB adsorption capacity was 630.28 ​mg/g. This work presents an efficient strategy to design porous nanomaterials with low shrinkage and large SSA, which illustrates promising applications in separation, adsorption, and photoelectric catalysis.