Engineering a Thermally Localized Janus Membrane for Solar-assisted CO2 Desorption

Abstract

While membrane reactors improve the energy efficiency of regenerating amine-based solvents, they do not overcome the inherently energy-intensive nature of the process. Herein, we present a novel solar-assisted CO2 stripping strategy that drastically reduces energy consumption via a Janus photothermal membrane reactor. Specifically, a delamination-free photothermal composite membrane was fabricated to alleviate the high energy cost associated with regenerating CO2-rich amine solutions. This hierarchically structured membrane (PM/C-PVA) consists of a thick PVDF mechanical support, an ultrathin superhydrophobic TBAOH-intercalated MXene- based photothermal layer, and a thin crosslinked polyvinyl acetate (C-PVA) layer that provides both optical transparency and thermal insulation. Combined with a tailored amino acid solvent absorbent, the system overcomes the high-temperature limitations of conventional thermal stripping. Operating at an initial 60 °C, the system achieves a CO2 desorption flux of 3.12 mmol m-2 s-1 while maintaining 76.2% of its maximum desorption efficiency measured at 120 °C. Under this condition, the energy consumption for regeneration is 1.45 GJ per ton of CO2, representing a 64% reduction compared to the conventional monoethanolamine (MEA) regeneration in standard stripping columns. Stabilized with polydimethylsiloxane (PDMS), the membrane (designated PPM/C-PVA) demonstrates robust operational stability, retaining over 85% of its initial performance after 120 h of continuous desorption. This exceptional durability and inherent cost-effectiveness position the membrane as a sustainable platform for direct solar-driven low-carbon solvent regeneration. This work delivers a sustainable carbon capture technology, establishing an efficient low-temperature regeneration pathway and cutting CO2 capture's carbon footprint via direct solar energy.