Acidic CO2 electroreduction to formic acid: catalyst-driven electrode reaction optimization and reactor-driven mass transport intensification

Abstract

The electrocatalytic CO₂ reduction reaction (eCO₂RR) to formic acid (FA, HCOOH) in acidic media represents a crucial technological pathway for achieving carbon neutrality. Compared to traditional neutral or alkaline systems, acidic environments can fundamentally prevent carbonate formation from a thermodynamic perspective, significantly enhance the single-pass carbon efficiency (SPCE), and directly produce high-purity FA, thereby simplifying downstream separation processes. However, the high proton concentration in the acidic environment severely restricts the selectivity and activity for FA, as well as the long-term stability of the catalysts. This review systematically summarizes recent advances in acidic eCO₂RR to FA from two key perspectives: catalyst-driven optimization of electrode reactions and reactor-driven intensification of mass transport. It focuses on catalyst performance modulation strategies that enhance the selectivity, activity, and stability of FA production under acidic conditions, while also detailing the structural advantages and research progress of acidic reactors in avoiding carbonate formation and enabling direct production of high-purity FA. Future research directions are outlined from the standpoint of microscopic reaction mechanisms and industrial applications. The review emphasizes that the synergistic design and integrated optimization of catalysts and reactors are crucial to advancing this technology from the laboratory toward industrial implementation.