Theoretical\nInvestigation of Electrocatalytic Reduction\nof Nitrates to Ammonia on Highly Efficient and Selective g‑C₂N Monolayer-Supported Single Transition-Metal Atoms

Abstract

Electrocatalytic\nreduction of nitrate (NO₃RR) to synthesize\nammonia (NH₃) can effectively degrade nitrate while producing\na valuable product. By utilizing density functional theory calculations,\nwe investigate the potential catalytic performance of a range of single\ntransition-metal (TM) atoms supported on nitrogenated holey doped\ngraphene (g-C₂N) (TM/g-C₂N) for the reduction\nof nitrates to NH₃. Based on the screening procedure, Zr/g-C₂N and Hf/g-C₂N are predicted as potential electrocatalysts\nfor the NO₃RR with limiting potential (<i>U</i>_L) values of −0.28 and −0.27 V, respectively.\nThe generation of byproducts such as dioxide (NO₂), nitric\noxide (NO), and nitrogen (N₂) is hindered on Zr/g-C₂N and Hf/g-C₂N due to the high energy cost. The\nNO₃RR activity of TM/g-C₂N is closely related\nto the adsorption free energy of NO₃^–. The study not only proposes a competent electrocatalyst for enhancing\nNO₃RR in ammonia synthesis but also provides a comprehensive\nunderstanding of the NO₃RR mechanism.