Electrocatalytic nitrate reduction on bimetallic Palladium-Copper Nanowires: Key surface structure for selective dinitrogen formation

Selective electrocatalytic nitrate reduction reaction (NO 3 RR) to dinitrogen (N 2 ) is essential to nitrogen-cycle management and environmental sustainability. Palladium-based nanomaterials were extensively studied as NO 3 RR catalysts, but only delivered limited N 2 selectivity (<50%, NH 3 dominated the product). Here we report that, by tuning bimetallic composition of CuPd alloy nanowires, the Cu 28 Pd 72 nanowires deliver a near-unit conversion of NO 3 – -N and an unprecedented N 2 product selectivity of 75.9 ± 5.2% in treating 22.5 mg L −1 NO 3 – -N solution at −0.80 V vs. Ag/AgCl. Combining in-situ spectrometric measurements and theoretical calculations, we demonstrate that the contiguous Pd ensemble with a specific size at catalyst surface is essential to the N 2 formation via a kinetically-favored pathway of NO 2 * → NO* → N* → N 2 *. Alloying Pd with Cu is indispensable as Cu contributes to the N*-N* pairing by initiating the NO 3 – –NO 2 * conversion and lowering the H ads coverage on catalyst. This work discloses the key surface atomic structure for N 2 formation, and provides a guideline for the design of efficient NO 3 RR catalyst that enables selective NO 3 – –N 2 conversion.