Engineering Nanoparticle-Mediated Interfacial Regulation of Deep Eutectic Solvents for Enhanced CO2 Capture and Solar-Driven Regeneration

Solar-driven carbon capture technology provides a promising strategy to address the high energy penalties associated with conventional amine-based chemical absorption. This study proposes a (MWCNTs-N-CQDs)@SiO2/ChCl-Gly-MEA nanofluid absorption system that integrates high heat/mass transfer with superior photothermal conversion characteristics. By tailoring the particle interfacial properties, specifically the specific surface area (170.35∼346.23 m2/g) and the density of Brønsted/Lewis acid sites (16.21∼24.05 μmol/g), the hydrogen-bond anchoring effect of ≡Si-OH and ≡Si+ acidic sites effectively disrupts the robust hydrogen-bonding network of the bulk ChCl-Gly-MEA phase. This structural disruption significantly reduces the system viscosity, thereby facilitating CO2 diffusion in the liquid phase while simultaneously inhibiting the H-donating effect to promote N-H bond cleavage in MEA. Furthermore, the CO2 absorption process is synergistically intensified by various microscopic particle effects, such as Brownian motion and the shuttle effect. The results demonstrate that the average CO2 absorption rate of the 0.02 wt % nanofluid is enhanced by 29.37% relative to the base fluid. Additionally, the loading of N-CQDs on the MWCNT surfaces along with the induced high-rugosity SiO2 clusters significantly enhances solar harvesting capabilities, endowing the nanofluid with excellent spectral absorption properties. Under concentrated solar irradiation (6500 W/m2), the CO2-rich nanofluid undergoes rapid photothermal heating to reach the required desorption threshold temperature. At a particle concentration of 0.05 wt %, the average desorption rate reaches 3.62 × 10-4 g/g·min-1 (under 400 r/min stirring). This interfacial modulation strategy offers a robust pathway for the synergistic intensification of CO2 capture and photothermal regeneration in nanofluid systems.