Rational Design of Ru@2D Polyaramid Enabling Ultra-Low Barrier and Dual-Product Selective CO ₂ Electroreduction

The search for efficient and highly selective electrocatalysts for the CO 2 reduction reaction (CO2RR) remains a major challenge due to the molecular stability of CO 2 and the competitive hydrogen evolution reaction (HER). By employing density functional theory (DFT) simulations, a metal–polymer hybrid (Ru-supported two-dimensional polyaramid, Ru@2DPA) electrocatalyst has been investigated for CO 2 RR. Among the five most active sites, the hexa (C–C) site exhibits the strongest adsorption energy of −3.32 eV, confirming its thermodynamic preference. Ru doping reduced the band gap from 2.54 eV to 0.9, and the shifting of the Fermi level toward the conduction band indicates an improvement in electron transport. Ab initio molecular dynamics at 400 K confirm the thermal stability of the system in both cases, i.e., pristine 2DPA and Ru-doped 2DPA. Gibbs free-energy analysis reveals two competing pathways (COOH and OCOH), where the initial CO 2 activation to *COOH requires only 0.18 eV, indicating favorable adsorption and activation on Ru@2DPA. Notably, the OCOH pathway is thermodynamically more favorable with a lower limiting potential (−0.42 V) compared to the COOH route (−0.33 V), highlighting its enhanced catalytic efficiency and selectivity. The present work highlights the potential of the metal-decorated 2DPA framework for sustainable carbon-neutral fuel production.