Spontaneously Generated Electrons for CO2 Hydrogenation to Formate at the Microinterface of Air‐Water

Abstract The periphery of the microdroplets exhibits unusual physical properties that are not observed in bulk solutions. This work demonstrates in water microdroplets OH − can spontaneously donate electrons for CO 2 hydrogenation to formic acid (FA), which may be driven by a strong electric field at or near the interfaces of water microdroplets. Surprisingly, Cu ions in microdroplets contribute to a 4000 times increase in output of FA. Control experiments show that in water microdroplets, electrons can be deposited by valence alternation of Cu to form Cu speciation, which can promote formate conversion. The authors show for the first time, without using any additives, under ambient conditions water microdroplets can capture CO 2 and reduce CO 2 to formate, which implies that water microdroplets may have provided a reactor for abiotic reduction reactions in the prebiotic era, thereby synthesizing organic molecules from atmospheric CO 2 with a nonenzymatic production power before the advent of biotic reducing types of machinery.