Boosting Nitrate Electroreduction to Ammonia on Alloying of Cu With Au by Accelerated Proton Relay

Abstract

Bimetallic nanoparticles (NPs) are recognized as effective catalysts for the nitrate reduction reaction (NO₃^–RR) to produce ammonia (NH₃) due to their multiple active sites and electron redistribution enabled by strong metal–metal interactions. An in-depth analysis of the reaction mechanism is essential for advancing efficient electrocatalysts. In this study, carbon-supported Au₃Cu alloy catalysts (Au₃Cu/CC) were synthesized and applied for the direct reduction of NO₃⁻ to NH₃. The NH₃ generation rate achieved with Au₃Cu/CC was 1719.3 µg h⁻¹ cm⁻², and the Faraday efficiency (FE) of NH₃ was measured at 95.1% under an ultra-low potential of −0.5 V versus RHE. The high activity of Au₃Cu/CC is attributed to the synergistic interactions between Au and Cu sites in relay catalysis, where Cu exhibits selective activity in the reduction of NO₃⁻ to *NO, while Au demonstrates excellent performance in the subsequent reduction of *NO to NH₃. Additionally, strong d–d orbital hybridization adjusts the d–band center of the alloy NPs, effectively modulating the adsorption energies of NO₃⁻ and *N to facilitate the direct reduction of NO₃⁻ to NH₃. This synergistic electrocatalytic approach offers a novel strategy for designing efficient and multifunctional NO₃⁻RR catalysts.

Keywords

alloying / orbital hybridization / relay catalysis

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