Efficient catalyst-free CO2 reduction by CO2− radical anions at gas–liquid interface under ambient conditions

The sustainable development of human society is critically dependent on atmospheric CO 2 concentration. Herein, we have developed a catalyst-free CO 2 reduction approach that utilizes mechanical energy to drive gas–liquid triboelectric plasma, enabling the generation of CO and O 2 at room temperature and atmospheric pressure through regulating the decomposition pathway of CO 2 − radical anions. The reactivity of CO 2 − radical anions is predominantly governed by the state of gas-phase triboelectric plasma and the composition of liquid-phase solution. Under optimized reaction conditions, this system achieves a remarkable CO production rate of 20.7 μmol h −1 with nearly 100 % selectivity and an exceptional electrical-to-chemical energy efficiency of 71.2 %. The introduction of water and potassium ions significantly enhances the conversion of CO 2 − radical anions through the formation of hydrated CO 2 − intermediates. Isotope labeling experiments, control experiments, and theoretical calculations confirm that water molecules and alkali cations effectively stabilize the highly reactive CO 2 — radical anions through hydrogen bonding and electrostatic interactions, reducing the dissociation barrier from 3.46 eV for gas phase CO 2 — to 2.48 eV in the presence of K + ions. Furthermore, the mechanical energy-driven gas–liquid triboelectric plasma system demonstrates excellent compatibility with aqueous solutions commonly encountered in daily life, maintaining superior CO production activity across various aqueous environments. This gas–liquid triboelectric plasma approach for CO 2 conversion not only provides a promising strategy for greenhouse gas mitigation, but also offers fundamental insights and a new perspective on CO 2 fixation at gas–liquid interfaces.