Nanoporous Copper–Palladium-Based Catalyst for Electrocatalytic Nitrate-to-Ammonia Conversion

Electrochemical nitrate reduction reaction (NO₃RR) is a green and environmentally friendly process with great potential for sustainable nitrogen cycle management and ecofriendly ammonia production. Development of catalysts with high Faradaic efficiency (FE) and ammonia yield is still a challenge for the large-scale industrial application of the NO₃RR. In this work, a self-supported nanoporous bimetallic Cu-Pd-based catalyst (np Cu-Pd@ZrCuAl) is prepared by dealloying and galvanic replacement. The np Cu-Pd@ZrCuAl catalyst exhibits excellent electrocatalytic performance for NO₃RR. The introduction of a tiny amount of Pd effectively enhances the H₂O dissociation to provide sufficient H atoms for NH₃ production, while suppressing the competitive hydrogen evolution reaction, leading to remarkable FE of 95% with a NH₃ yield rate of 21.46 mg h^-1 cm^-2. Theoretical calculations show that the Cu/Pd heterostructure modifies the electronic structure of Cu, optimizes the adsorption behavior of the intermediates, and reduces the energy barrier of the rate-determining ammonia desorption step, leading to fast ammonia generation. This work provides a valuable strategy for the design and synthesis of electrocatalysts for the NO₃RR via heterostructure construction.