Bottom-up synthesis of two-dimensional carbon with vertically aligned ordered micropores for ultrafast nanofiltration

Diversity in Atomic Structures of Zeolite-Templated Carbons and the Consequences for Macroscopic Properties

Zeolite-templated carbons (ZTCs) are a family of ordered microporous carbons with extralarge surface areas and micropore volumes, which are synthesized by carbon deposition within the confined spaces of zeolite micropores. There has been great controversy regarding the atomic structures of ZTCs, which encompass two extremes: (1) three-dimensionally connected curved open-blade-type carbon moieties and (2) ideal tubular structures (commonly referred to as "Schwarzites"). In this study, through a combination of experimental analyses and theoretical calculations, we demonstrate that the atomic structure of ZTCs is difficult to define as a single entity, and it widely varies depending on their synthesis conditions. Carbon deposition using a large organic precursor and low-temperature framework densification generates ZTCs predominantly composed of open-blade-type moieties, characterized by low surface curvature and abundant H-terminated edge sites. Meanwhile, synthesis using a small precursor with high-temperature densification produces ZTCs with an increased portion of closed-strut carbon moieties (or closed-fullerene-like nodes), exhibiting large surface curvature and diminished edge sites. The variations in the atomic structure of ZTCs result in significant differences in their macroscopic properties, such as N2/CO2 adsorption, oxidative stability, work function, and electrocatalytic properties, despite the presence of comparable pore structures. Therefore, ZTCs demonstrate the potential to synthesize ordered nanoporous carbons with tunable physicochemical properties.

Methanol recovery: potential of nanolaminate organic solvent nanofiltration (OSN) membranes

Researchers have made a significant breakthrough by merging the energy-saving attribute of organic solvent nanofiltration (OSN) with the remarkable solvent permeance and solute rejection of two-dimensional (2D) laminated membranes. This innovative approach brings forth a new era of sustainable and cost-effective separation techniques, presenting a promising solution to the issue of industrial solvents contaminating the environment. This development paves the way for new opportunities in building a sustainable future. Specifically, our mini-review has cast a spotlight on the separation and recovery of methanol-a solvent abundantly used in industrial processes. We systematically evaluated a diverse array of free-standing 2D nanolaminate OSN membranes. The analysis encompasses the assessment of pure methanol permeance, solute rejection capabilities, and the simultaneous evaluation of methanol permeance and solute rejection performance. Notably, this study sheds light on the considerable potential of 2D laminated OSN membranes in revolutionizing separation processes for the industrial use of methanol.