Enhanced post-combustion CO2 capture and direct air capture by plasma surface functionalization of graphene adsorbent

Abstract

Graphene has enormous potential to capture CO₂ due to its unique properties and cost-effectiveness. However, graphene-based adsorbents have drawbacks of lower CO₂ adsorption capacity and poor selectivity. This work demonstrates a one-step rapid and sustainable N₂/H₂ plasma treatment process to prepare graphene-based sorbent material with enhanced CO₂ adsorption performance. Plasma treatment directly enriches amine species, increases surface area, and improves textural properties. The CO₂ adsorption capacity increases from 1.6 to 3.3 mmol/g for capturing flue gas, and from 0.14 to 1.3 mmol/g for direct air capture (DAC). Importantly, the electrothermal property of the plasma-modified aerogels has been significantly improved, resulting in faster heating rates and significantly reducing energy consumption compared to conventional external heating for regeneration of sorbents. Modified aerogels display improved selectivity of 42 and 87 after plasma modification for 5 and 10 min, respectively. The plasma-treated aerogels display minimal loss between 17% and 19% in capacity after 40 adsorption/desorption cycles, rendering excellent stability. The N₂/H₂ plasma treatment of adsorbent materials would lower energy expenses and prevent negative effects on the global economy caused by climate change.