Pressure-Driven Interfacial Microenvironment Regulation for Highly Selective Acidic CO2 Electroreduction

Acidic electrocatalytic CO2 reduction (CO2RR) can mitigate carbonate crossover and deposition issues inherent in conventional neutral/alkaline systems, yet it faces the dual challenges of severe hydrogen evolution reaction (HER) competition and local salt precipitation that deactivates electrodes. To address these issues, this work integrates a crack-mitigated, hydrophobic Ag/C composite catalyst layer with a CO2 pressurization strategy to construct a pressurized acidic MEA electrolyzer. At pH = 1 and a CO2 pressure of 3 bar, the system achieves a CO Faradaic efficiency (FECO) of 99.1% at 50 mA cm-2 and maintains a stable FECO above 94% for over 45 h at 200 mA cm-2, with no observable carbonate deposition on the electrode surface. Multiphysics simulations and DFT calculations reveal that pressurization not only shifts the carbonate formation zone toward the catalyst layer-membrane interface to establish a buffering layer that suppresses HER but also optimizes the CO2 surface coverage, thereby lowering the *COOH formation barrier and promoting *CO desorption. This work achieves microenvironment regulation through a facile physical approach, providing a new paradigm for the scalable development of acidic CO2 electrolysis.