Zr-MOF/MXene composite for enhanced photothermal catalytic CO2 reduction in atmospheric and industrial flue gas streams

Abstract

In this study, a novel composite was engineered by integrating Zr-MOF (NH₂-UIO-66) with MXene layers through electrostatic self-assembly. Under simulated sunlight and at 80 °C, this composite material achieved nearly complete conversion of low-concentration atmospheric CO₂ to CO and CH₄ without additional sacrificial agents or alkaline absorption liquids, marking one of the few reports demonstrating near-complete reduction of low-concentration CO₂ directly from the air. For high-concentration CO₂ in industrial flue gas, the composite utilized residual heat at 80 °C without additional energy input, exhibiting excellent CO₂ reduction efficiency with CO and CH4 production rates of 127 μmol·g^-1·h^-1 and 330 μmol·g^-1·h^-1, respectively, resulting in a total production rate 4.76 times higher than that in the air. Compared to most reports on thermocatalytic CO₂ reduction (>300 °C), this material shows significant advantages below 100 °C. The performance improvement is attributed to the introduction of Zr-MOF, which provides additional active sites and reduces activation energy. Additionally, the localized surface plasmon resonance (LSPR) effect of MXene facilitates the migration of thermal charge carriers to Zr⁴⁺ sites within the MOF. Density Functional Theory (DFT) calculations validate these findings. Overall, Zr-MOF/MXene composite holds potential for reducing CO₂ in air and industrial settings, advancing energy conversion and environmental management.