Electrochemical regeneration of high-purity CO2 from (bi)carbonates in a porous solid electrolyte reactor for efficient carbon capture

Abstract

Carbon dioxide (CO₂) and absorbent regeneration are the most energy-intensive processes in carbon capture loops. Conventional carbon capture technologies typically consume substantial amounts of heat and involve multiple steps for regeneration. Here we demonstrated one-step electrochemical regeneration of CO₂ and alkaline absorbent from carbon-containing solutions in a modular porous solid electrolyte (PSE) reactor. By performing hydrogen evolution and oxidation redox reactions, our PSE reactor selectively split NaHCO₃/Na₂CO₃ solutions, which typically come from air contactors after CO₂ absorption, into NaOH absorbent in the catholyte and high-purity CO₂ gas in the PSE layer. No chemicals were consumed and no by-products were generated. High Na⁺-ion transport number (~90%), high capture capacity retention (~90%), low energy consumptions (50 kJ mol_CO2⁻¹ and 118 kJ mol_CO2⁻¹ at 1 mA cm⁻² and 100 mA cm⁻² for bicarbonate, respectively) and long-term stability (>100 hours) were demonstrated. We achieved industrially relevant carbon regeneration rates of up to 1 A cm⁻² (~18 mmol cm⁻² h⁻¹), highlighting the promising application potential.