Alkali-Metal-Modified Al-PMOF for Enhanced CO₂ Adsorption and Photocatalytic Reduction

In this paper, M-Al-PMOF (M = Na, K) composites were synthesized for the first time by incorporating alkali metals into Al-PMOFs. Comprehensive experiments were conducted to investigate the CO2 adsorption and photocatalytic reduction capabilities of the synthesized composites with different doping amounts and types of alkali metals. The results show that doping alkali metals into Al-PMOFs efficiently enhanced their CO2 adsorption by increasing the surface area and alkaline sites. Moreover, the modified materials exhibit improved light absorption, reduced band gap, and suppressed recombination of photogenerated electron–hole pairs, leading to a significantly enhanced photocatalytic CO2-to-CO conversion efficiency. Notably, the 1-K-Al-PMOF sample showed a 45% increase in CO2 adsorption capacity compared to that of pristine Al-PMOF, along with a 6.6 times enhancement in the CO production yield. This work reveals that different amounts and types of doped alkali metals can improve their CO2 absorption and photocatalytic reduction properties, offering a perspective for designing and modifying MOFs.