Acidic\nElectrocatalytic CO₂ Reduction Using\nSpace-Confined Nanoreactors

Abstract

Electrochemical\nCO₂ reduction reaction (CO₂RR) is an attractive\nstrategy for sustainable production of chemicals\nand has mainly been implemented in alkaline or neutral electrolytes.\nHowever, part of input CO₂ is consumed by the formation\nof carbonate under these conditions. Herein, a space-confined strategy\nis proposed for CO₂RR in acidic media, and Ni nanoparticles\nare encapsulated inside N-doped carbon nanocages as yolk–shell\nnanoreactors. By confining CO₂RR in the cavities of nanoreactors,\na Faradaic efficiency (FE) of 93.2% for CO is achieved at pH 7.2\nand 84.3% FE for CO at pH 2.5. The inhibited proton diffusion within\nthe Nernst layer of a nanoreactor is responsible for suppression of\ncompeting hydrogen evolution in acid. Moreover, CO₂RR in\nan acidic flow electrolysis system offers enhanced current density\nand sustainable operation, in comparison with the conventional neutral\npH system. This work shows that steering of mass transport via a unique\nstructure is a viable avenue toward selective CO₂ conversion,\nand it provides a further understanding of the structure–performance\nrelationship of electrocatalysts.