Interfacial reaction microenvironment engineering for promoting acidic CO₂ electrocatalytic reduction

The electrocatalytic CO₂ reduction reaction (CO₂RR) in acidic media effectively circumvents the carbonate precipitation commonly encountered in neutral and alkaline systems. As the CO₂RR typically occurs at the gas–liquid–solid three-phase interface, regulating the local microenvironment around the catalytic center is crucial for enhancing reaction activity. This review systematically summarizes recent progress in microenvironment engineering for acidic CO₂RR interfacial reactions. Firstly, the concept of the interface reaction microenvironment is elaborated, and the core elements of the CO₂RR interface reaction microenvironment under acidic conditions are summarized, including in situ local (interfacial) pH evolution, interface water structure, and double-layer electric field distribution. From the perspective of catalyst design, microenvironment regulation strategies based on confinement effects, surface wettability modulation, and interfacial electric field construction are discussed in detail. Subsequently, from the viewpoint of electrolyte engineering, advances in solution pH control, buffer system design, and alkali metal cation regulation are reviewed. Finally, the opportunities and challenges facing interfacial reaction microenvironment engineering in the development of the acidic CO₂RR are discussed.