Recent advances in activated carbons for CO ₂ capture: Structure–performance relationships and future perspectives

The continuous rise in atmospheric CO 2 concentration is a major driver of climate change, underscoring the urgent need for efficient capture technologies. Activated carbons (ACs) are among the most promising adsorbents because they are inexpensive, structurally tunable, and exhibit excellent moisture resistance. This review critically examines recent advancements (2022–2025) in AC-based sorbents for CO 2 capture by integrating findings from 30 representative studies covering biomass- and waste-derived precursors, heteroatom-doped carbons, and composite materials. Under near-ambient conditions, ultramicropores (<0.7 nm) dominate CO 2 adsorption, with uptake capacities ranging from 6 to 9 mmol g −1 despite wide variations in brunauer-emmett-teller surface area. Surface chemistry further enhances performance: pyridinic and pyrrolic nitrogen species, as well as oxidized sulfur functional groups, strengthen interactions with CO 2 and significantly improve both uptake and CO 2 /N 2 selectivity, reaching values up to 161 in olive-stone-derived carbons. Thermodynamic analyses indicate an optimal isosteric heat of adsorption (Qst) window of 20–35 kJ mol −1 , ensuring a balanced trade-off between adsorption affinity and regenerability. Stability assessments consistently demonstrate that physisorption-dominated ACs retain more than 90–99% of their initial capacity across multiple cycles, supporting their potential for industrial deployment. Nevertheless, challenges remain related to large-scale production, sustainable precursor selection, performance in humid or impurity-rich conditions, and energy-efficient regeneration processes. Future research directions include the utilization of green and waste-derived precursors, precise pore engineering, targeted heteroatom doping, and the development of hybrid AC/metal–organic framework or AC/oxide composite sorbents. Overall, ACs—particularly those derived from renewable or waste resources—offer a robust and versatile platform for CO 2 capture. Through combined structural, chemical, and thermodynamic optimization, these materials can transition from promising laboratory prototypes to scalable solutions for post-combustion and direct air capture applications.