Unlocking the Comparative Potential of Porous Frameworks: A Review on MOFs and COFs for Gas Sorption

Abstract

Gases are integral to Earth's climate and ecosystem balance, but human activity has significantly altered atmospheric composition by increasing greenhouse gas emissions. In 2025, carbon dioxide emissions were estimated at around 39-41 billion tons, reflecting a continued increase. Emissions of carbon monoxide, sulfur dioxide, and nitrogen dioxide were expected to remain close to 2.5 billion tons, 100 million tons, and 25 million metric tons, respectively. Hydrogen sulfide emissions decreased to 15 million tons compared with the previous year. These numbers underscore the challenge of addressing human-induced climate changes. Sorbents, particularly metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been used in literature for their gas sorption applications. Over the past decade, modified frameworks have been explored for their potential in gas sorption by combining the advantages of the different materials involved. The properties of these frameworks can be tailored by using various functional groups, metal ions, and polymer matrices. The structures of MOFs and COFs, their synthesis methods, and gas sorption applications are discussed. In addition, the applications of modified MOFs and COFs in gas sorption and separation (CO₂ sorption from flue gas, hydrocarbon separation, separation of hydrocarbons, and iodine capture from nuclear waste), detection (NO₂ sensing), and reduction (SO₂ to reduced sulfur components) are discussed. It also explores the emerging aspects of enhancing gas sensing and capturing abilities of MOFs and COFs, analyzing their performance under different conditions of temperature, pressure, and relative humidity. The study addresses the challenges faced by existing frameworks and suggests directions for developing better materials.

Keywords: Covalent organic frameworks; Gas separation; Metal organic frameworks; Sensing; Sorption.