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

Abstract

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.