Breaking the Limit of Size-Dependent CO₂RR Selectivity in Ag Nanoparticle Electrocatalysts through Electronic Metal-Carbon Interactions: Insights from Computational Hydrogen Electrode Calculations

Experiments show that metal-carbon interactions between small diameter Ag particles and defective carbon supports can improve electochemical CO₂ reduction activity and break the size-dependent selectivity trend traditionally associated with coinage-metal catalysts. Specifically, < 2 nm diameter Ag electrocatalysts grown on a defective carbon support demonstrate a CO Faradaic efficiency of ~100% and turnover frequency of 2 CO/atom_Ag/s at -1.3 V vs. the reversible hydrogen electrode. X-ray photoelectron spectroscopy identifies a new Ag^d+ feature in Ag particles grown on defective graphite that indicates Ag-C interaction and the resulting charge transfer slightly depletes electron density in the Ag nanoparticles. Due to the current challenges in designing in situ interfacial experimental probes, we apply the computational hydrogen electrode approach to rationalize the experimental findings. The calculations predict a charge transfer from the Ag nanoparticle to a defective carbon surface, stabilizing the *COOH intermediate through reduced antibonding orbital overlap, significantly reducing the *COOH formation energy barrier, and improving CO₂-to-CO conversion selectivity compared with Ag nanocluster on defect-free carbon. These results provide new insights into carbon-supported electrocatalysts for CO₂RR and introduce a new approach for creating active and selective nanocatalysts.