Silk-Nano-Fibroin Aerogels: A Bio-Derived, Amine-Rich Platform for Rapid and Reversible CO₂ Capture

Despite growing interest in biobased materials, rapid, low-temperature CO₂ capture using amine-rich natural sorbents has received limited attention. Various porous solid sorbents have drawn significant research interest as promising carbon capture materials. However, high synthesis cost, limited CO₂ adsorption capacity, sluggish adsorption-desorption kinetics, high sorbent regeneration temperature, and poor operational stability remain major challenges for their practical implementation. Here, we present silk-nanofibroin aerogels derived from natural mulberry silk as a sustainable, amine-rich, and porous solid-support-free sorbent platform for energy-efficient CO₂ capture. The aerogels exhibit a CO₂ adsorption capacity competitive with state-of-the-art amino acid and amino acid ionic liquid-based solid sorbents. Thermogravimetric analysis confirms high thermal stability up to ∼250 °C─substantially higher than that of conventional amine sorbents─while complete sorbent regeneration occurs at only 60 °C. Furthermore, the silk-nanofibroin aerogels demonstrate rapid adsorption-desorption kinetics, excellent multicycle stability, and full retention of CO₂ adsorption capacity under humid conditions. Spectroscopic analyses (XPS, FTIR, Raman, and solid-state ¹³C NMR) confirm reversible CO₂ chemisorption through intrinsic amine sites at the silk-fibroin surface. Overall, this work establishes silk-nanofibroin aerogels as a sustainable and low-cost route toward energy-efficient CO₂ capture.