Work

Silver Porphyrins for Efficient CO 2 ‐to‐CO Conversion in Zero‐Gap Electrolyzers—Effects of Dispersion Solvent and Ligand Substituents

Year: 2026

Type: article

Abstract: ABSTRACT Molecular pre‐catalysts—especially silver‐based systems—are promising alternatives for generating metallic materials for the electrochemical CO 2 reduction (eCO 2 R). Yet, their implementation in industrially relevant electrolyzer architectures remains challenging. Herein, silver tetraphenylporphyrin ( AgTPP ) and its fluorine‐ and methoxy‐substituted analogs ( AgF 20 and AgDMPP ) were investigated as such pre‐catalysts in zero‐gap electrolyzers (ZGEs) at current densities of up to 500 mA/cm 2 . Instead of ligand‐substitution effects, eCO 2 R activity and efficiency were predominantly affected by the local environment within the catalyst layer (CL) of the gas diffusion electrode (GDE). The parent complex AgTPP was able to achieve the highest Faradaic efficiency for CO (FE CO ) of 75% at a constant current electrolysis at 300 mA/cm 2 with an ultra‐low pre‐catalyst loading of 0.05 mg/cm 2 . We found that the dispersion solvent strongly influenced CL morphology, leading to notable differences in CO selectivity, with FE CO values ranging from 13% to 75% under identical electrolysis conditions at 300 mA/cm 2 . Ligand modification negligibly affected CO selectivity with an optimized dispersion solvent but drastically influenced the overall cell voltage, underscoring the crucial role of local catalyst environment for an overall efficient eCO 2 R performance in ZGEs.

Source: ChemCatChem

DOI: 10.1002/cctc.71073