A new predictive descriptor for accelerating DAC material design

Achieving energy-efficient Direct Air Capture (DAC) requires the rational design of inorganic sorbents with optimized thermodynamic properties. This study introduces a novel, unified thermodynamic framework that bridges diverse inorganic materials, including metal oxides, hydroxides, and hydrogen carbonates. By defining a revised electronegativity difference I r , which incorporates metal‑oxygen bonding and anion structural factors, disparate thermodynamic data are successfully collapsed onto universal master curves. The results establish a definitive predictive design rule: materials capable of capturing atmospheric CO 2 at equilibrium concentrations below 3 ppm must possess an I r within the narrow range of 2.07 to 2.11. Furthermore, for energy-efficient regeneration at ~373 K, metal hydrogen carbonates with an I r of 1.77–1.81 and water vapor desorption are required. The hydrated Na 2 CO 3 /NaHCO 3 system ( I r = 2.08/1.78) is identified as an exceptionally promising candidate for next-generation DAC. This framework provides a powerful tool for accelerating the discovery of materials essential for climate change mitigation.