Mechanistic Understanding of the Electrocatalytic Nitrate Reduction Activity of Double-Atom Catalysts
Nadaraj Sathishkumar, Hsin‐Tsung Chen
Abstract
Electrochemical nitrate reduction reaction (NO 3 RR) has promise for both nitrogen pollution management and low-temperature ammonia production instead of the conventional Haber–Bosch process. Nevertheless, it relies on electrocatalysts with controllable reaction pathways and product selectivity. Herein, we design novel homonuclear double-atom catalysts (DACs) supported on N-doped graphene (TM 2 /N 6 -G) as potential NO 3 RR catalysts using first-principles calculations. The results reveal that Cr 2 /N 6 -G, Mn 2 /N 6 -G, and Cu 2 /N 6 -G serve as the most promising NO 3 RR catalysts, as they exhibit stability, excellent activity, high selectivity (faradic efficiency of >61.28%), and low limiting potentials (−0.46, −0.45, and −0.36 V for Cr 2 /N 6 -G, Mn 2 /N 6 -G, and Cu 2 /N 6 -G, respectively). In addition, multiple-level descriptors and volcano plots provide insight into the origin of NO 3 RR activity and enable fast prescreening among numerous candidates. Furthermore, considerable potential energy barriers are found in the formation of byproducts NO 2, NO, and N 2 O, validating their high selectivity. The conversion of nitrate to ammonia is more competitive than the hydrogen evolution reaction on Cr 2 /N 6 -G, Mn 2 /N 6 -G, and Cu 2 /N 6 -G possessing a lower limiting potential. This study provides a guideline for the rational design of highly active, selective, and durable electrocatalysts in NO 3 RR.