A computational study of electric field-controlled CO2 Capture using earth-abundant metals

Abstract

With the growing urgency to combat climate change, developing energy-efficient and tunable direct air capture (DAC) technologies for CO₂ removal has become an urgent scientific and engineering challenge. This study explores a novel strategy that leverages external electric fields (EFs) and surface charges to modulate CO₂ adsorption and desorption on low-cost, earth-abundant metal surfaces with varying d-orbital occupancies. Using Density Functional Theory (DFT), we systematically investigated Cu (111), Fe (110), and Zn (0001) surfaces, representing moderate, high, and inert reactivity, respectively.

Without external stimuli, Fe (110) intrinsically chemisorbs CO₂, while Cu (111) and Zn (0001) surfaces exhibit only weak physisorption. Upon application of an EF and excess surface charge, all three surfaces show enhanced CO₂ activation, with the effect being most pronounced on Cu (111) surface. The application of an EF leads to a transition from physisorption to chemisorption, accompanied by significant molecular activation. Reversing the field with a modest potential (∼ -2 V) enables efficient CO₂ desorption, completing a low-energy capture-release cycle. In contrast, Fe binds CO₂ too strongly, rendering desorption ineffective even under a strong reverse field (-40 V), while Zn remains largely unresponsive due to filled d-orbitals, showing minimal activation for CO₂ adsorption even at high field strengths (30 V).

Among the three, Cu (111) emerges as the most promising candidate for electrically tunable CO₂ capture, offering a balance between reactivity and reversibility due to its nearly filled d-band configuration. By elucidating the crucial roles of d-orbital occupancy and electric field sensitivity, this work presents electrically modulated adsorption and desorption as an effective carbon capture mechanism that eliminates the need for chemical functionalization, surface modification, or energy-intensive thermal or pressure processes. This approach opens new pathways for designing tunable CO₂ capture systems through targeted material selection and electric field engineering.