Tensile-strained silver assembly enables ampere-level electrochemical CO2-to-CO conversion across a wide pH range

Abstract

The electrochemical conversion of CO2 to CO is a promising approach for sustainable chemical production. However, its practical application is constrained by sluggish CO2 activation and strong pH-dependent product selectivity. In this study, we report a grain boundary-enriched silver assembly (Ag-GB) catalyst synthesized via a self-assembly method. The Ag-GB catalyst achieves a Faradaic efficiency for CO (FECO) exceeding 92.1% across a wide current density range of 0.08-1.38 A/cm2 in a neutral electrolyte, with a maximum FECO of 99.1% and a peak CO partial current density of 1.28 A/cm2. Under acidic conditions, it reaches a peak FECO of 97.8% and maintains stable operation for 100 h. Structural analysis reveals that the dense grain boundaries in Ag-GB induce significant tensile strain in the Ag lattice. In situ ATR-FTIR spectroscopy confirms the enhanced stabilization of the critical *COOH intermediate on the Ag-GB surface. Computational simulations further corroborate that tensile strain synergistically strengthens *COOH adsorption while suppressing competitive *H evolution, thereby steering the reaction pathway exclusively toward CO production. This study presents an effective structural engineering approach to simultaneously enhance selectivity, productivity, and pH tolerance in the electrochemical conversion of CO2 to CO.