Tailoring Asymmetric RuCu Dual-Atom Electrocatalyst toward Ammonia Synthesis from Nitrate

Abstract

Atomically dispersed dual-atom catalysts (DACs) with asymmetric coordination are pivotal for enhancing economic efficiency and sustainable development in the electrochemical nitrate reduction reaction (NO₃RR) to produce ammonia. However, rational design and rapid synthesis of DACs remain challenging. Here, we demonstrate the pulsed discharge method, which generates microsecond current pulses to inject substantial energy instantaneously into ruthenium (Ru) and copper (Cu) metal salt precursors supported by nitrogen-doped graphene aerogels (NGA). This process results in the atomically dispersed Ru and Cu dual atoms anchoring onto nanopore defects of NGA (RuCu DAs/NGA) through explosive decomposition of the metal salt nanocrystals. X-ray absorption spectroscopy analysis suggests an asymmetric RuN₂-CuN₃ coordination structure on NGA. The RuCu DAs/NGA catalyst exhibits outstanding electrochemical performance in NO₃RR, achieving a Faraday efficiency of 97.8% and an ammonia yield rate of 3.07 mg h^− 1 cm^− 2 at -0.4 V vs. RHE. In situ studies monitor the evolution of RuCu active sites and reaction intermediates during the NO₃RR process in real time. Density functional theory calculations reveal that the Ru-Cu sites in the asymmetric RuN₂CuN₃/C structure create a synergistic effect, optimizing intermediate adsorption and lowering the energy barrier of key elementary reactions. This pulsed discharge method is simple, ultra-fast, and versatile (e.g., applicable to PtCu, AgCu, and PdCu DAs on NGA), offering a general-purpose strategy for the precise preparation of atomically dispersed dual-atom catalysts, which are traditionally challenging to synthesize.