Enabling Unconventional “Alternating-Distal” N2 Reduction Pathway for Efficient Ammonia Electrosynthesis

Abstract

The general understanding on the reaction path is that the electrocatalytic N2 reduction follows either individual associative alternating or distal pathways, where efficient N2 activation and selective NH3 production are very challenging. Herein, an unconventional “alternating-distal” pathway was achieved by shifting the “*NHNH2→*NH2NH2” to “*NHNH2→*NH + NH3” step to boost NH3 synthesis with an amorphous CeMnOx electrocatalyst. In this unconventional process, N2 activation was realized through π back donation on the Mn site, while the Mn/Ce dual active sites could regulate the intermediate configurations to avoid the nitrogen-containing by-product formation. Such “alternating-distal” pathway was affirmed by in situ spectroscopic analyses and theoretical calculations. In a neutral media, an average ammonia production rate of 82.8 µg h−1 mg−1 and an outstanding Faradaic efficiency of 37.3% were attained. This work validated an unconventional mechanism in electrocatalytic ammonia synthesis, which might be extended to other catalytic process with multiple possible reaction paths.