Regeneration of direct air CO2 capture liquid via alternating electrocatalysis

Abstract

The direct air capture (DAC) of carbon dioxide (CO₂) can potentially contribute to mitigating past and offsetting hard-to-abate future emissions; however, the regeneration of DAC capture liquids requires high temperatures and thermal energy inputs with emissions that diminish their net environmental benefit. Here, we present a low-temperature electrochemical process to regenerate alkaline capture liquids via alternating electrocatalysis (AE). Colocating oxidation and reduction reactions on a single electrode, cycled between electrolyzer and fuel cell modes, mitigates film formation and losses in the regeneration of alkali hydroxide and hydrogen halide. CO₂ can be captured and released with an energy input of 6.4 GJ/tCO₂ at 100 mA cm⁻² and an emission intensity of ∼11 kg CO₂e/tCO₂.