Tailoring microenvironment of adsorbents to achieve excellent CO₂ uptakes from wet gases

Due to the excellent adsorption capacity on CO₂, Mg-MOF-74 is highly potential for carbon capture. However, the practical application is seriously hindered by the poor hydrolytic stability of Mg-MOF-74 even towards trace of moisture. Here we report a strategy by adjusting the microenvironment of Mg-MOF-74 from hydrophilic to superhydrophobic by coating polydimethylsiloxane (PDS, yielding M74@P), which markedly enhances the hydrolytic stability. Mg-MOF-74 is degraded obviously upon exposure to humid atmosphere (75% relative humidity) for 7 days, while M74@P retains its structure well even after 1 year. The dynamic breakthrough results show that the optimized M74@P sample can capture 6.65 mmol g⁻¹ CO₂ from wet CO₂/N₂ mixtures after 100 cycles, which is superior to Mg-MOF-74 (1.17 mmol g⁻¹) and most reported adsorbents under comparable conditions (continuous flow adsorption from wet gases). The excellent adsorption capacity and hydrolytic stability make the present adsorbents highly promising for practical applications in carbon capture.