Computation-Guided Design of Ru-Based Intermetallic Catalysts Enabling Nearly 100% Selectivity for Electrocatalytic Ammonia Synthesis at Ultra-Low Potential

Abstract

Electrochemical nitrate reduction reaction (NO₃RR) holds significant promise for converting the NO₃^⁻ pollutants into valuable ammonia (NH₃), offering a sustainable alternative to the energy-intensive Haber-Bosch process by operating under mild conditions with renewable energy sources. However, unsuitable adsorption of *NO₃ and inadequate supply of active hydrogen (*H) during the NO₃RR process lead to low Faradaic efficiency in NH₃ production. Herein, density functional theory calculations are initially employed to evaluate the adsorption energies of *NO₃ and *H adsorption energy for 13 Ru-p-block metal intermetallic compounds (IMCs). The results demonstrate that Ru-Sb IMCs exhibit great potential as NO₃RR electrocatalysts, demonstrating exceptional NO₃⁻ adsorption capacity and efficient suppression of competing hydrogen evolution reaction, outperforming the other Ru-p-block metal IMCs. As guided by the calculation results, Ru-Sb IMCs supported on carbon black is synthesized, i.e., RuSb/C and RuSb₂/C. And RuSb/C exhibits impressive NO₃RR performance with an NH₃ Faradaic efficiency of nearly 100% (99.7%) and exceptional stability at a low potential of -0.05 V, significantly exceeding those of most recently reported Ru-based electrocatalysts for NO₃RR.