Acidic CO2 electroreduction to formic acid at low overpotentials over Cu modified with a dual site polymer

Abstract

Acidic CO₂ electroreduction to HCOOH provides a promising strategy for renewable energy storage and CO₂ recycling. However, under acidic conditions, it typically exhibits poor selectivity at low overpotentials. Here, we report the first work demonstrating that CO₂ can be efficiently reduced to HCOOH over a Cu catalyst by modifying with a dual site polymer under acidic conditions. The selectivity for HCOOH is significantly enhanced at low overpotentials, and the faradaic efficiency for HCOOH can reach 87.4% with an energy efficiency of 56%. This is the highest energy efficiency for HCOOH under acidic conditions to date. Experiments and density functional theory calculations revealed that the dual sites in the polymer can promote CO₂ reduction and stabilize the key intermediate *OCHO, resulting in high selectivity for HCOOH at low overpotentials.