Highly Selective Acidic CO2 Electroreduction with Large Current on Polypyrrole‐Modified Ag Catalyst by Local Microenvironment Modulation

By modifying PPy on the surface of Ag NPs, the interfacial microenvironment can be effectively regulated to reduce the energy barrier of CO₂RR, inhibit competitive HER, and protect the catalyst from strong acid corrosion. The electrocatalytic activity and selectivity of acidic CO₂ electroreduction are significantly improved at high current density.

Abstract

Electrocatalytic carbon dioxide reduction (CO₂RR) holds great promise for carbon capture and utilization. In acidic media, CO₂RR enables efficient CO₂ conversion, but with low selectivity due to the competitive hydrogen evolution reaction (HER) and catalyst corrosion. Herein, conductive polymer polypyrrole (PPy) coated Ag nanoparticles (NPs) catalysts (Ag@PPy) with different thicknesses are designed and synthesized, which could create a hydrophobic environment that reduces the accessibility of H₂O to the Ag NPs thereby inhibiting HER. The coating of the PPy layer also protects the catalysts from corrosion and improves the stability of the system. Among them, Ag@PPy-2 with the appropriate thickness showed up to 91.7% for the electrocatalytic reduction of CO₂ to CO and high durability in acidic electrolyte at −300 mA cm⁻². Density functional theory (DFT) calculation shows that Ag nanoparticles coated with PPy not only inhibit the competitive HER, but also reduce the CO₂RR energy barrier, and improve the efficiency of CO₂ to CO. This study may provide some new ideas for the design of advanced selective electrocatalytic CO₂ reduction catalysts by local microenvironmental engineering.