Dealloying layered PdBi2 nanoflakes to palladium hydride leads to enhanced electrocatalytic N2 reduction

Abstract

Electrochemical catalysis of nitrogen to ammonia is an environmentally friendly alternative strategy to the traditional and damaging Haber–Bosch process. Nevertheless, it is limited by a low ammonia yield and faradaic efficiency due to (i) the complexity associated with the breaking of the NN bond and (ii) the competing hydrogen evolution reaction. Herein, we report that the electrochemical dealloying of exfoliated PdBi₂ nanoflakes into palladium hydride greatly enhances the electrocatalytic nitrogen reduction reaction. The electrochemical decomposition of bismuth atoms creates vacancies in the PdBi₂ crystal lattice enabling hydrogen atoms to be absorbed and instigating the initial protonation of N₂ molecules necessary for the eventual NH₃ formation. The average ammonia yield and faradaic efficiency were 30.06 ± 1.16 μg cm⁻² h⁻¹ and 15.25 ± 1.29% when the potential was held at −1.5 V vs. sat. Ag/AgCl after 6 h at room temperature. Our conclusions are supported by the first-principles simulations and this work emphasizes the potential implementation of palladium compounds for future N₂ reduction reaction electrocatalysts.